JP7844449B2 - Display of three-dimensional objects - Google Patents

Description

By reference, this application claims priority to U.S.S.N. 63/079,707, filed on 17 September 2020, entitled “Displaying Three-Dimensional Objects,” and U.S.S.N. 63/149,964, filed on 16 February 2021, entitled “Reconstructing Objects with Display Zero Order Light Supplement,” the entire contents of which are incorporated herein by reference.

This disclosure relates to a three-dimensional (3D) display, and more specifically, to a 3D display involving object reconstruction.

Advances in conventional two-dimensional (2D) projection and 3D rendering have given rise to new approaches to 3D displays, including numerous hybrid technologies that combine head tracking and eye tracking with conventional display devices for virtual reality (VR), augmented reality (AR), and mixed reality (MR). These technologies, combined with tracking and measurement-based computation, attempt to recreate the experience of holographic images and simulate the stereo or intra-eye light field that can be represented by actual holograms.

This disclosure describes methods, apparatus, devices, and systems for reconstructing objects (e.g., 2D or 3D), particularly those involving display zero-order light suppression. This disclosure provides techniques that can efficiently suppress display zero-order light (e.g., reflected, diffracted, or transmitted) from the display in the reconstructed holographic scene (or holographic content) to improve the effect of the holographic scene and, consequently, the performance of the display system. As an example, when light illuminates a display for holographic reconstruction, a portion of the light is modulated by the hologram and incident on the display elements forming the desired holographic scene, where it is diffracted by the display elements. Other portions of the light are incident on the gaps between the display elements on the display and are reflected by the gaps. The other reflected portions of the light can be considered at least some (e.g., primary order) of display zero-order light that may be presented undesirably in the holographic scene. Display zero-order light can also include any other unwanted light from the display, such as light diffracted in the gaps, reflected light from the display elements, or reflected light from the display cover on the display. Embodiments of this disclosure can suppress such display zero-order light.

In some implementations, the hologram is configured such that a first portion of light irradiated onto the display elements of the display is diffracted by the hologram-modulated display elements and has at least one characteristic distinct from the zero-order display light, which includes reflected light from the display. The zero-order display light may include a second portion of light irradiated onto the gap between the display elements and reflected from the gap, without modulation of the hologram. The technique can utilize the difference between the diffracted first portion of light and the zero-order display light (e.g., the reflected second portion of light) to suppress the zero-order display light in the holographic scene formed by the diffracted first portion of light. The technique can be applied individually or in combination. The technique can be applied to any other display system that suppresses or removes undesirable light from desired light.

In some examples, the display is configured to suppress higher-order zero-order display light, for example, by including irregular or non-uniform display elements having different sizes. The display elements are non-periodic and can form a Voronoi pattern. In some examples, in a holographic scene, the zero-order display light can have a much lower power density than the first diffracted portion of the light. That is, the zero-order display light is suppressed by increasing the signal-to-noise ratio of the holographic scene, for example by causing the zero-order display light to diverge without the divergence of the first diffracted portion of the light, or by adjusting the phase of each display element within a predetermined phase range such as [0, 2π], or both. In some examples, the zero-order display light is suppressed by directing the zero-order display light away from the first diffracted portion of the light, for example by illuminating the display at an incident angle such that the first diffracted portion of the light still propagates around the vertical axis and the zero-order display light propagates at the reflection angle, thereby pre-configuring the hologram. Display zero-order light can be redirected by adding, for example, an additional optical diffraction grating structure to the outside of the holographic scene formed by the first diffracted portion of the light, thereby directing the display zero-order light further away from the holographic scene. Display zero-order light can also be reflected backward away from the holographic scene. Display zero-order light can also be absorbed in front of the holographic scene.

In this disclosure, the terms "zero order" and "zero-order" are used interchangeably, and the terms "first order" and "first-order" are used interchangeably.

In this disclosure, the terms "zero order" and "zero-order" are used interchangeably, and the terms "first order" and "first-order" are used interchangeably.

One aspect of this disclosure is characterized by irradiating a display with light, wherein a first portion of the light irradiates the display elements of the display, modulates the display elements of the display with a hologram corresponding to holographic data, i) diffracting the first portion of the light to form a holographic scene corresponding to the holographic data, and ii) suppressing zero-order display light in the holographic scene, wherein the zero-order display light includes reflected light from the display.

In some examples, illuminating a display with light includes a second portion of the light illuminating the gap between adjacent display elements. The zero-order display light may include at least one of the following: a second portion of light reflected by the display gap, a second portion of light diffracted by the display gap, reflected light from the display elements, or reflected light from the display cover enclosing the display.

The reflected light from the display can be configured to form primary-order zero-order display light and suppress one or more higher-order zero-order display light, and the display elements can be irregular or non-uniform. In some examples, the display elements form a Voronoi pattern.

In some implementations, the method further includes configuring the hologram such that the first diffracted portion of the light has at least one property distinct from the zero-order light of the display. The at least one property may include at least one of power density, beam divergence, propagation direction away from the display, or polarization state.

In some implementations, display zero-order light is suppressed in the holographic scene by a light suppression efficiency. Light suppression efficiency is defined as 1 minus the ratio of the amount of display zero-order light in the suppressed holographic scene to the amount of display zero-order light in the unsuppressed holographic scene. In some cases, the light suppression efficiency exceeds a predetermined percentage, one of 50%, 60%, 70%, 80%, 90%, or 99%. In some cases, the light suppression efficiency is 100%.

In some implementations, the method further includes determining the EM field contribution to each of the display elements of a display by calculating the electromagnetic (EM) field propagation from the primitive to the display element in a global three-dimensional (3D) coordinate system for each of the multiple primitives corresponding to the object, and generating the sum of the EM field contributions from the multiple primitives to the display element for each of the display elements. Holographic data may include the sum of the EM field contributions from the multiple primitives of the object to the display elements of the display. Holographic scenes may include reconstructed objects corresponding to the object.

In some implementations, the holographic data includes the phase of each display element of the display, and the method further includes constructing a hologram by adjusting the phase of each display element to have a predetermined phase range. The predetermined phase range can be [0, 2π].

In some implementations, adjusting the phase of each display element is possible.
,
This includes adjusting the respective phases accordingly.
During the ceremony,
These represent the initial phase values of each phase,
The values shown represent the adjusted phase values for each phase, and A and B are constants.

In some implementations, adjusting each phase involves adjusting constants A and B so that the light suppression efficiency of the holographic scene is maximized. The light suppression efficiency may be greater than 50%, 60%, 70%, 80%, 90%, or 99%. In some cases, adjusting constants A and B involves adjusting them using a machine vision algorithm or a machine learning algorithm.

In some implementations, the method further includes diverging a first diffracted portion of light to form a holographic scene, and diverging display zero-order light in or adjacent to the holographic scene. In some examples, diverging a first diffracted portion of light includes guiding the first diffracted portion of light through an optical divergent component located downstream of the display, and diverging display zero-order light includes guiding the display zero-order light through an optical divergent component.

In some examples, the light illuminating the display is collimated light. The zero-order light of the display is collimated before reaching the optically divergent components, and the method may further configure the hologram such that the diffracted first portion of the light converges before reaching the optically divergent components.

In some implementations, the holographic data includes the respective phase for each of the display elements. The method may further include constructing a hologram by adding a corresponding phase to each of the display elements, the corresponding phase for each display element may be compensated by an optical divergent component such that the holographic scene corresponds to the respective phase of each display element. The corresponding phase for each of the display elements is,
,
It can be expressed as,
During the ceremony,
λ represents the corresponding phase for the display element, λ represents the wavelength of light, f represents the focal length of the optical divergent component, x and y represent the coordinates of the display element in the coordinate system, and a and b represent constants.

In some implementations, the holographic scene corresponds to a reconstructed cone with a field of view. The method may further include: moving a constituent cone relative to a global 3D coordinate system, along a direction perpendicular to the display, by a distance corresponding to the focal length of the optical divergent component, such that the constituent cone corresponds to the reconstructed cone and has the same apex angle as the field of view; and generating holographic data based on the moved constituent cone in the global 3D coordinate system. Multiple primitives of an object may reside within the moved constituent cone.

In some implementations, the optical divergence component is a defocusing element comprising at least one of a concave lens or a holographic optical element (HOE) configured to diffract the zero-order light of the display outside the holographic scene.

In some implementations, the optical divergence component is,
The focusing element includes at least one convex lens or holographic optical element (HOE) configured to diffract the zero-order light of the display outside the holographic scene.

In some implementations, the method further includes displaying a holographic scene on a two-dimensional (2D) screen spaced away from the display along a direction perpendicular to the display. The method may further include moving the 2D screen to obtain different slices of the holographic scene on the 2D screen.

In some implementations, the method further includes inducing light to illuminate a display. In some examples, inducing light to illuminate a display includes inducing light by a beam splitter, and the diffracted first portion of the light and the zero-order light of the display are transmitted through the beam splitter.

In some implementations, illuminating a display with light includes illuminating the display with light perpendicularly incident to it.

In some implementations, the first diffracted portion of light forms a reconstructed cone with a viewing angle, and illuminating the display with light includes illuminating the display with light at an incident angle greater than half of the viewing angle. In some examples, the method further includes structuring the hologram such that the first diffracted portion of light forms the same reconstructed cone as the reconstructed cone formed by the first diffracted portion of light when light is normally incident on the display.

In some examples, holographic data includes the respective phase for each display element. The method may further include constructing a hologram by adding a corresponding phase to each of the display elements, where the corresponding phase for each display element can be compensated for by the angle of incidence, such that the holographic scene corresponds to the respective phase of each display element.

In some examples, the corresponding phase for each display element is:
,
It can be expressed as,
During the ceremony,
λ represents the corresponding phase for the display element, λ represents the wavelength of light, x and y represent the coordinates of the display element in the global 3D coordinate system, and θ represents the angle corresponding to the angle of incidence.

In some examples, constructing a hologram involves moving a constructing cone relative to a display in a global 3D coordinate system, wherein the constructing cone corresponds to a reconstructed cone and has an apex angle corresponding to the viewing angle of the reconstructed cone, and generating holographic data based on the moved constructing cone in the global 3D coordinate system.

In some examples, moving a component cone relative to the display in a global 3D coordinate system includes rotating the component cone relative to the display surface in a global 3D coordinate system by an angle of rotation, where the angle of rotation corresponds to the angle of incidence.

In some implementations, the method further includes blocking the appearance of zero-order display light in the holographic scene. The light suppression efficiency of the holographic scene may be 100%. In some examples, blocking zero-order display light includes guiding the zero-order display light toward an optically blocked element located downstream of the display. The method may further include guiding a first portion of the light diffracted to transmit through the optically blocked element with a transmission efficiency, thereby forming the holographic scene. The transmission efficiency may not fall below a predetermined ratio. The predetermined ratio may be 50%, 60%, 70%, 80%, 90%, or 99%.

In some implementations, the optical blocking component is configured to transmit a first light beam having an angle smaller than a predetermined angle and to block a second light beam having an angle larger than the predetermined angle, where the predetermined angle is smaller than the incident angle and greater than half of the field of view. The optical blocking component may include multiple microstructures or nanostructures, metamaterial layers, or optically anisotropic films.

In some implementations, the method further includes guiding light to illuminate a display by guiding it through an optical diffraction component on a substrate configured to diffract light at an angle of incidence. Guiding light to illuminate a display may include at least one of the following: guiding light to the optical diffraction component through a waveguide coupler, guiding light to the optical diffraction component through a coupling prism, or guiding light to the optical diffraction component through a wedge-shaped surface of the substrate.

In some implementations, the optical diffraction component is formed on a first surface of the substrate facing the display, and the optical shielding component is formed on a second surface of the substrate opposite to the first surface.

In some implementations, the method further includes redirecting the zero-order light of the display away from the holographic scene. The light suppression efficiency of the holographic scene can be 100%.

In some implementations, redirecting the display zero-order light away from the holographic scene involves diffracting the display zero-order light from the holographic scene using an optical redirection component located downstream of the display. The optical redirection component can be configured to transmit the diffracted first portion of the light to form the holographic scene.

In some implementations, the optical redirection component is configured such that the zero-order light of the display is diffracted outwards in three-dimensional (3D) space along at least one of the following directions: upward, downward, leftward, rightward, or a combination thereof.

In some implementations, the optical redirection component is configured to diffract a first light beam having the same angle as a predetermined angle with substantially greater diffraction efficiency than a second light beam having a different angle, where the predetermined angle is substantially the same as the angle of incidence. The optical redirection component may include a Bragg grating.

In some implementations, the optical diffraction component is formed on a first surface of the substrate facing the display, and the optical redirection component is formed on a second surface of the substrate opposite to the first surface.

In some cases, the angle of incidence of light is negative, and the diffraction angle of the zero-order display light diffracted by the optical redirection component is negative. In some cases, the angle of incidence of light is positive, and the diffraction angle of the zero-order display light diffracted by the optical redirection component is positive. In some cases, the angle of incidence of light is negative, and the diffraction angle of the zero-order display light diffracted by the optical redirection component is positive. In some cases, the angle of incidence of light is positive, and the diffraction angle of the zero-order display light diffracted by the optical redirection component is negative.

In some implementations, the optical redirection component is covered by a second substrate. The method further includes absorbing the zero-order display light redirected by the optical redirection component and reflected by the interface between the second substrate and the surrounding medium, by a light absorber formed on the side surface of the second substrate or on at least one of the side surfaces of the substrate.

In some implementations, the second substrate includes an anti-reflective coating on the surface of the second substrate opposite to the optical redirection component, and the anti-reflective coating is configured to transmit zero-order light of the display.

In some implementations, the zero-order display light is p-polarized before reaching the second substrate, and the optical redirection component is configured to diffract the zero-order display light so that it is completely transmitted through the second substrate and incident at a Brewster angle at the interface between the second substrate and the surrounding medium.

In some implementations, the method further includes converting the polarization state of the display zero-order light from s-polarization to p-polarization before the display zero-order light reaches the second substrate. In some cases, converting the polarization state of the display zero-order light includes converting the polarization state of the display zero-order light by an optical polarizing device positioned upstream of the optical redirection component relative to the display.

In some cases, transforming the polarization state of the zero-order light of a display involves transforming the polarization state of the zero-order light of a display by an optical polarizing device positioned downstream of the optical redirection component relative to the display. The optical polarizing device may include an optical retarder and an optical polarizer positioned sequentially downstream of the optical redirection component, where the optical retarder may be formed on the side of a second substrate opposite to the optical redirection component, and the optical polarizer is covered by a third substrate. In some examples, the optical retarder includes a broadband half-wave plate, and the optical polarizer includes a linear polarizer.

In some implementations, the second substrate includes a first side above the optical redirection component and a second side opposite to the first side. An optical shielding component can be formed on the second side of the second substrate and is configured to transmit the diffracted first portion of light and absorb the zero-order display light diffracted by the optical redirection component.

In some implementations, the optical blocking component includes an optical anisotropic transmitter configured to transmit a first light beam having an angle smaller than a predetermined angle and absorb a second light beam having an angle larger than a predetermined angle. The predetermined angle can be greater than half the field of view and smaller than the diffraction angle at which the zeroth-order light of the display is diffracted by the optical redirection component.

In some implementations, the optical redirection component is configured to diffract the zero-order display light and direct it to the interface between the second substrate and the surrounding medium at an angle greater than the critical angle; therefore, the zero-order display light diffracted by the optical diffraction component is completely reflected at the interface. A light absorber can be formed on the substrate and the side surfaces of the second substrate and configured to absorb the completely reflected zero-order display light.

In some implementations, the light contains multiple different colors, and the optical diffraction component is configured to diffract multiple different colors of light at the angle of incidence on the display.

In some implementations, an optical redirection component includes a separate optical redirection subcomponent for each of several different colored lights. In some examples, each optical redirection subcomponent for several different colored lights can be recorded in the same recording structure. In some examples, each optical redirection subcomponent for several different colored lights is recorded in a different corresponding recording structure.

In some implementations, the optical redirection component is configured to diffract multiple different colored lights in 3D space in different directions and at different diffraction angles. The optical redirection component can be configured to diffract at least one of the multiple different colored lights and incident it at the interface at at least one Brewster angle. The interface may include one of the interfaces between the upper substrate and the surrounding medium, or between two adjacent substrates.

In some implementations, the optical redirection component is configured to diffract light of a first and second color in a plane, as well as light of a third color orthogonal to the plane. In some implementations, the optical redirection component includes at least two different optical redirection subcomponents configured to diffract light of the same color from a plurality of different colors. The two different optical redirection subcomponents can be arranged sequentially within the optical redirection component.

In some implementations, guiding light to illuminate a display involves sequentially guiding multiple different colored lights to illuminate the display over a series of periods. In some implementations, the optical redirection component includes a switchable optical redirection sub-component configured to diffract light of a first color in a first state during a first period and transmit light of a second color in a second state during a second period. In some implementations, the optical redirection component includes a switchable optical redirection sub-component configured to diffract light of a first color in a first state during a first period and diffract light of a second color in a second state during a second period.

In some implementations, the multiple different colored lights include a first color and a second color, the first color having a shorter wavelength than the second color, and in the optical redirection component, the first optical redirection subcomponent for the first color of light is positioned closer to the display than the second optical redirection subcomponent for the second color of light.

In some implementations, the fringe planes of at least two optical redirection subcomponents for at least two different colors of light are oriented in substantially different directions.

In some implementations, the optical redirection component includes a first optical redirection subcomponent configured to diffract light of a first color, a second optical redirection subcomponent configured to diffract light of a second color, and at least one optical polarizing device positioned between the first and second optical redirection subcomponents and configured to transform the polarization state of the first color light so that the first color light is transmitted through the second optical redirection subcomponent. The at least one optical polarizing device may include an optical retarder and an optical polarizer positioned sequentially downstream of the first optical redirection subcomponent.

In some cases, half of the field of view is within the range of -10 to 10 degrees, or -5 to 5 degrees. In some cases, the angle of incidence is -6 degrees or 6 degrees.

Another aspect of this disclosure is characterized by a method comprising irradiating a display with light, wherein a portion of the light irradiates the display elements of the display, and generating a holographic scene by diffracting a portion of the light while suppressing the zero-order display light present in the holographic scene, wherein the zero-order display light includes reflected light from the display.

In some implementations, suppressing display zero-order light present in a holographic scene involves diverging the display zero-order light.

In some implementations, generating a holographic scene by diffracting the light portion involves modulating the display elements in the hologram. Suppressing the zero-order display light present in the holographic scene may include adjusting the phase range of the hologram.

In some implementations, illuminating a display with light includes illuminating the display with light at a certain angle of incidence, and suppressing zero-order display light present in a holographic scene may include modulating a portion of the light with a hologram configured such that a portion of the light is diffracted by the display elements at a diffraction angle different from the reflection angle at which the reflected light is reflected. In some cases, suppressing zero-order display light present in a holographic scene includes blocking the zero-order display light with an angle-dependent material. The angle-dependent material may include a metamaterial or an optically anisotropic material.

In some implementations, suppressing zero-order display light present in a holographic scene includes redirecting the zero-order display light. Redirecting the zero-order display light may include diffracting it using optical diffraction components. The light may contain light of different colors, and redirecting the zero-order display light may include diffracting light of different colors in different directions in three-dimensional (3D) space.

In some implementations, suppressing display zero-order light present in a holographic scene includes suppressing it with a light suppression efficiency of a predetermined ratio or higher. The light suppression efficiency is defined as the result of subtracting from 1 the ratio of the amount of display zero-order light in the suppressed holographic scene to the amount of display zero-order light without suppression. The predetermined ratio may be 50%, 60%, 70%, 80%, 90%, or 100%.

Another feature of this disclosure is an optical device comprising an optical diffraction component and an optical shielding component. The optical diffraction component is configured to diffract light at a certain angle of incidence to illuminate a display element of a display with a portion of the light, and the optical shielding component is configured to shield the display zero-order light in a holographic scene formed by the portion of light diffracted by the display element, the display zero-order light including reflected light from the display.

In some implementations, optical devices are configured to perform the methods described above.

In some implementations, the display is configured to be modulated with a hologram corresponding to holographic data, diffracting portions of light to form a holographic scene, and the optical blocking component is configured to transmit the diffracted portions of light to form the holographic scene. The diffracted portions of light can form a reconstructed cone with a viewing angle, and the angle of incidence can be greater than half of the viewing angle.

The optical blocking component can be configured to transmit a first light beam having an angle smaller than a predetermined angle and to block a second light beam having an angle larger than the predetermined angle. The predetermined angle can be smaller than the incident angle and larger than half of the field of view.

In some implementations, the optical shielding component includes a metamaterial layer or an optically anisotropic film. In some implementations, the optical shielding component includes multiple microstructures or multiple nanostructures.

In some implementations, the optical device further includes a substrate having both sides. Optical diffraction components and optical shielding components can be formed on both sides of the substrate.

Another aspect of this disclosure features a method for manufacturing such an optical device, comprising forming an optical diffraction element on a first side of a substrate and forming an optical shielding element on a second side of the substrate opposite to the first side.

Another aspect of this disclosure features an optical device comprising an optical diffraction component and an optical redirection component. The optical diffraction component is configured to diffract light at a certain angle of incidence onto a display comprising a plurality of display elements spaced apart by gaps on the display. The display is configured to diffract a portion of the light illuminating the display elements. The optical redirection component is configured to transmit a portion of the light to form a holographic scene and redirect zero-order light away from the holographic scene in three-dimensional (3D) space, the display zero-order light including reflected light from the display.

In some examples, optical redirection components include Bragg gratings.

In some implementations, the optical diffraction component is formed on a first side of the substrate facing the display, and the optical redirection component is formed on a second side of the substrate opposite to the first side.

In some implementations, the optical device further includes a second substrate covering the optical redirection component. In some implementations, the optical device further includes a light absorber formed on at least one of the sides of the substrate or the side of the second substrate, the light absorber being configured to absorb display zero-order light redirected by the optical redirection component and reflected by the interface between the second substrate and the surrounding medium.

In some implementations, the optical device further includes an anti-reflective coating formed on a second substrate and opposite the optical redirection component, the anti-reflective coating configured to transmit the zero-order display light redirected by the optical redirection component.

In some implementations, the optical device further includes an optical polarizing device configured to convert the polarization state of the display zero-order light from s-polarization to p-polarization before the display zero-order light arrives at the second substrate, and the optical redirection component is configured to diffract the display zero-order light so that it passes through the second substrate and is incident at a Brewster angle at the interface between the second substrate and the surrounding medium. The optical polarizing device may include an optical retarder and a linear polarizer arranged in sequence together.

In some implementations, the optical polarizing device is positioned upstream of the optical redirection component relative to the display. In some implementations, the optical polarizing device is formed on a second substrate opposite to the optical redirection component, and the optical polarizing device is covered by a third substrate.

In some implementations, the optical device further includes an optical shielding component formed on the second substrate side opposite to the optical redirection component, the optical shielding component being configured to transmit a portion of the light and absorb the zero-order display light diffracted by the optical redirection component. The optical shielding component may include an optically anisotropic transmitter.

In some implementations, the optical redirection component is configured to diffract the zero-order display light and cause it to be incident at an angle greater than the critical angle at the interface between the second substrate and the surrounding medium. Therefore, the zero-order display light diffracted by the optical diffraction component is completely reflected at the interface.

In some implementations, the light includes light of multiple different colors. An optical diffraction component is configured to diffract light of multiple different colors at an incident angle on the display, and an optical redirection component can be configured to diffract the zero-order light of multiple different colors reflected by the display in different directions in 3D space at different diffraction angles. The display zero-order light includes the reflected light of multiple different colors by the display.

In some implementations, the optical diffraction component includes multiple holographic gratings for multiple different colors of light, and each of the multiple holographic gratings is configured to diffract light of each of the multiple different colors at the angle of incidence on the display.

In some implementations, the optical redirection component includes multiple redirection holographic gratings for the zero-order display light of multiple different colors, and each of the multiple redirection holographic gratings is configured to diffract the zero-order display light of each of the multiple different colors in its respective direction in 3D space at its respective diffraction angle.

In some implementations, the optical redirection component includes at least two different redirection holographic gratings configured to diffract the zero-order light of the same color among several different colored lights.

In some implementations, the optical redirection component includes a switchable redirection holographic grating configured to diffract light of a first color in a first state during a first period and transmit light of a second color in a second state during a second period.

In some implementations, the optical redirection component includes a switchable redirection holographic grating configured to diffract light of a first color in a first state during a first period and to diffract light of a second color in a second state during a second period.

In some implementations, the light of multiple different colors includes a first color and a second color, the first color having a shorter wavelength than the second color, and in the optical redirection component, the first redirection holographic grating for the first color is positioned closer to the display than the second redirection holographic grating for the second color.

In some implementations, the fringe planes of at least two redirect holographic gratings for at least two different colors of light are oriented in substantially different directions.

In some implementations, the optical redirection component includes a first redirection holographic grating configured to diffract light of a first color, a second redirection holographic grating configured to diffract light of a second color, and at least one optical polarizing device positioned between the first and second redirection holographic gratings and configured to transform the polarization state of the light of the first color so that the light of the first color is transmitted through the second redirection holographic grating.

In some implementations, optical devices are configured to perform the method described above.

Another aspect of this disclosure features a method for manufacturing such an optical device, comprising forming an optical diffraction component on a first side of a substrate and forming an optical redirection component on a second side of the substrate opposite to the first side.

Another aspect of this disclosure features a system including a display comprising display elements separated by a gap on the display, and an optical device configured to illuminate the display with light, such that a portion of the light illuminates the display elements. The system is configured to form a holographic scene by diffracting portions of light while suppressing zero-order display light in the holographic scene. The zero-order display light may include at least one of the following: reflected light from the gap, diffracted light from the gap, reflected light from the display elements, or reflected light from the display cover that surrounds the display.

In some implementations, the system further includes a controller coupled to the display and configured to modulate the display elements of the display with a hologram corresponding to the holographic data, thereby diffracting the light portion and forming a holographic scene corresponding to the holographic data. The hologram can be configured such that zero-order display light is suppressed within the holographic scene.

In some implementations, the system further includes a computing device configured to generate primitives of one or more objects corresponding to a holographic scene. The system can be configured to perform such a method. The optical device may include one or more of the optical devices described above.

In some implementations, the system further includes an optical divergent device positioned downstream of the optical device and configured to diverge the zero-order light of the display within the holographic scene. The light illuminating the display is collimated light. The zero-order light of the display is collimated before reaching the optical divergent device, and the hologram is configured such that the diffracted portions of the light converge before reaching the optical divergent device.
The optical divergence device may include the optical divergence components described above.

In some implementations, the system further includes a two-dimensional (2D) screen positioned downstream of the display. In some implementations, the optical device includes a beam splitter. In some implementations, the optical device includes a waveguide with in-couplers and out-couplers. In some implementations, the optical device includes a light guide including an optical coupler and an optical diffraction component. The optical coupler may include a coupling prism. The optical coupler may also include a wedge-shaped substrate.

Another aspect of this disclosure features a method for creating such a system.

Another aspect of this disclosure features an optical device comprising at least two beam expanders configured to expand an input light beam of at least two dimensions by diffracting the input light beam and adjusting the beam size of the input light beam of at least two dimensions, thereby generating an output light beam. The beam size may include width and height.

In some implementations, each of at least two beam expanders includes its own optical diffraction device. The input light beam may contain light of multiple different colors, and each optical diffraction device may be configured to diffract light of multiple different colors at their respective diffraction angles, which are substantially identical to each other.

In some examples, each optical diffraction device is configured to separate individual light of different colors while suppressing crosstalk between those colors when light of different colors is incident upon it.

In some implementations, each optical diffraction device includes at least two optical diffraction components and at least one color-selective polarizer.

In some implementations, each optical diffraction device includes at least two optical diffraction components and at least one reflective layer. The at least one reflective layer may be configured for total internal reflection of light of at least one color.

In some implementations, each optical diffraction device includes at least one of one or more transmission diffraction structures or one or more reflection diffraction structures.

In some implementations, the beam expander includes at least two beam expanders: a first one-dimensional beam expander configured to expand an input optical beam of a first dimension (of at least two dimensions) to produce an intermediate optical beam; and a second one-dimensional beam expander configured to expand an intermediate optical beam of a second dimension (of at least two dimensions) to produce an output optical beam. The intermediate optical beam has a beam size larger than that of the input optical beam of the first dimension and the same beam size as the input optical beam of the second dimension, and the output optical beam has a beam size larger than that of the intermediate optical beam of the second dimension and the same beam size as the intermediate optical beam of the first dimension.

In some implementations, the optical device is configured to couple an intermediate light beam from a first one-dimensional beam expander to a second one-dimensional beam expander using at least one of free-space aerial geometry, a monolithic substrate or a segmented substrate, or one or more coupling elements.

In some implementations, the intermediate input beam contains collinear, collimated light of two or more colors, and one or more coupling elements are configured to convert the collinear, collimated light of two or more colors into two or more independently parallel but non-collinear light beams having corresponding colors of two or more colors.

This disclosure also describes, in particular, methods, apparatus, devices, and systems for displaying three-dimensional (3D) objects by individually diffracting light of different colors. This disclosure provides techniques that can efficiently separate light of different colors or wavelengths to suppress (e.g., reduce or eliminate) crosstalk between colors or wavelengths. The techniques can also suppress light from propagating through an optical diffraction device without diffraction and striking the display at undesirable angles, thereby suppressing undesirable effects such as ghost images. The techniques enable the sequential or simultaneous reconstruction of multi-color three-dimensional optical fields or images with little to no crosstalk. The techniques enable the implementation of an illumination system to provide multiple nearly perpendicular polarized beams of different colors with relatively large incident angles. Thus, the techniques enable the presentation of an optical field or image to a viewer (e.g., an observer or user) in front of the display without interference from the illuminator, and reduce power loss due to reflection, diffraction, and/or scattering, for example. The techniques also enable the implementation of a compact optical system for displaying three-dimensional objects.

This disclosure provides a technology that can overcome the limitations present in known technologies. For example, the technology disclosed herein can be implemented without the use of cumbersome wearable devices such as "3D glasses." Alternatively, the technology disclosed herein can be optionally implemented without being limited by the accuracy of the tracking mechanism, the quality of the display device, relatively long processing times and/or relatively high computational requirements, and/or the inability to display objects simultaneously to multiple viewers. Further, the technology can be implemented without dedicated tools and software for developing content that extends beyond the tools and software used for conventional 3D content creation. Various embodiments can demonstrate one or more of the aforementioned advantages. For example, a particular implementation of this disclosure can generate real-time, full-color, authentic 3D images that appear to be real 3D objects in the world and can be simultaneously and uninterruptedly viewed by multiple viewers from different points of view.

One aspect of this disclosure is characterized by a method comprising: determining the electromagnetic field contribution to each of the elements of a display by calculating the electromagnetic field propagation from the primitive to the element in a 3D coordinate system for each of the primitives corresponding to an object in three-dimensional (3D) space; and generating the sum of the electromagnetic field contributions from the primitives to the element for each of the elements.

The EM field contribution may include at least one of either a phase contribution or an amplitude contribution. A primitive may include at least one of a point primitive, a line primitive, or a polygon primitive. A primitive may include a line primitive containing at least one of a gradient color, a texture color, or any surface shading effect. A primitive may also include a polygon primitive containing at least one of a gradient color, a texture color, or any surface shading effect. Multiple primitives can be indexed in a specific order.

In some implementations, the method further includes obtaining primitive data for each of a plurality of primitives. Each primitive data for each of the plurality of primitives may include the primitive's respective color information, and the determined EM field contribution for each element includes information corresponding to the primitive's respective color information. The color information may include at least one of texture color or gradient color. Each primitive data for each of the plurality of primitives may include the primitive's texture information. Each primitive data for each of the plurality of primitives may include shading information on one or more surfaces of the primitive. The shading information may include at least one modulation of color or luminance on one or more surfaces of the primitive.

In some implementations, each primitive data of multiple primitives includes the coordinate information of each primitive in a 3D coordinate system. The coordinate information of each element in a 3D coordinate system can be determined based on the coordinate information of each primitive in the 3D coordinate system. The coordinate information of each element can correspond to the logical memory address of the element stored in memory.

Determining the EM field contribution of each of the elements for each of the multiple primitives may include determining at least one distance between the element and the primitive in a 3D coordinate system, based on the coordinate information of each element and the coordinate information of each primitive. In some examples, determining the EM field contribution of each of the elements for each of the multiple primitives may include determining a first distance between the first primitive and the first element of the multiple primitives, based on the coordinate information of each first primitive and the coordinate information of each first element; and determining a second distance between the first primitive and the second element of the multiple elements, based on the first distance and the distance between the first element and the second element. The distance between the first and second elements may be predetermined based on the pitch of the multiple elements on the display.

In some examples, at least one of the multiple primitives is a line primitive containing a first endpoint and a second endpoint, and determining at least one distance between the element and the primitive includes determining a first distance between the element and the first endpoint of the line primitive, and determining a second distance between the element and the second endpoint of the line primitive. In some examples, at least one of the multiple primitives is a triangle primitive containing a first endpoint, a second endpoint, and a third endpoint, and determining at least one distance between the element and the primitive includes determining a first distance between the element and the first endpoint of the triangle primitive, determining a second distance between the element and the second endpoint of the triangle primitive, and determining a third distance between the element and the third point of the triangle primitive.

In some implementations, determining the EM field contribution of each of several elements for each of several primitives involves determining the EM field contribution from the primitive to the element based on a predetermined equation for the primitive and at least one distance. In some cases, the predetermined equation is determined by analytically calculating the EM field propagation from the primitive to the element. In some cases, the predetermined equation is determined by solving Maxwell's equations. Maxwell's equations can be solved by providing boundary conditions defined on the surface of the display. The boundary conditions may include Dirichlet or Cauchy boundary conditions. The several primitives and several elements may be in 3D space, and the surface of the display may form a portion of the boundary surface of 3D space. In some cases, the predetermined equation includes at least one function, including a sine function, a cosine function, or an exponential function, and determining the EM field contribution involves identifying at least one value of the function in a table stored in memory.

In some implementations, determining the EM field contribution of each of the multiple elements for each of the multiple primitives, and generating the sum of the field contributions for each of the multiple elements, includes determining the first EM field contribution from the multiple primitives to the first element among the multiple elements, summing the first EM field contribution for the first element, determining the second EM field contribution from the multiple primitives to the second element among the multiple elements, and summing the second EM field contribution for the second element. Determining the first EM field contribution from the multiple primitives to the first element may include performing in parallel the determination of the EM field contribution from the first primitive among the multiple primitives to the first element, and the determination of the EM field contribution from the second primitive among the multiple primitives to the first element.

In some implementations, determining the EM field contribution of each of the elements for each of the multiple primitives includes determining the first EM field contribution of a first primitive among the multiple primitives to each of the multiple elements, and determining the second EM field contribution of a second primitive among the multiple primitives to each of the multiple elements. Generating the sum of the field contributions for each of the multiple elements may include accumulating the EM field contribution for an element by adding the second EM field contribution to the first EM field contribution for that element. Determining the first EM field contribution of each of the multiple elements from the first primitive can be performed in parallel with determining the second EM field contribution of each of the multiple elements from the second primitive.

Determining the EM field contribution of each of the multiple elements for each of the multiple primitives can include simultaneously determining the first EM field contribution from the first primitive among the multiple primitives to the first element among the multiple elements, and simultaneously determining the second EM field contribution from the second primitive among the multiple primitives to the first element.

In some implementations, the method further includes generating a control signal for each of a plurality of elements based on the sum of the EM field contributions from a plurality of primitives to the element, wherein each control signal is for tuning at least one property of the element based on the sum of the EM field contributions from the plurality of primitives to the element. The at least one property of the element may include at least one of refractive index, amplitude exponent, birefringence, or delay. Each control signal may include an electrical signal, optical signal, magnetic signal, or acoustic signal. In some cases, the method further includes multiplying the sum of the field contributions for each of the elements by a scaling factor to obtain a scaled sum of the field contributions, and each control signal is generated based on the scaled sum of the field contributions for the element. In some cases, the method further includes normalizing the sum of the field contributions for each of the elements, and each control signal is based on the normalized sum of the field contributions for the element. The method may also include transmitting each control signal to the element.

In some implementations, the method further includes transmitting a control signal to an irradiator, the control signal indicating that the irradiator is to be activated to emit light onto the display. The control signal may be transmitted in response to determining the completion of obtaining the sum of the field contributions for each of a plurality of elements. Modulated elements of the display can propagate light in different directions to form a volume light field corresponding to an object in 3D space. The volume light field may correspond to a solution of Maxwell's equations with boundary conditions defined by the modulated elements of the display. The light may include white light, and the display may be configured to diffract the white light into light of different colors.

In some implementations, the method further includes representing values using fixed-point representation during computation. Each value can be represented as an integer with an implicit scaling factor.

In some implementations, the method further includes performing mathematical functions using fixed-point representation. The mathematical functions may include at least one of sine, cosine, and arctangent. Performing a mathematical function may include receiving an expression in a first fixed-point format and outputting a value in a second fixed-point format having a different precision level than the first fixed-point format. Performing a mathematical function may include examining a table for the calculation of the mathematical function, the table including at least one of a fully enumerated lookup table, an interpolated table, a half-table-based polynomial function, and a half-table based on a full minimax polynomial. Performing a mathematical function may include applying a special range reduction to the input. Performing a mathematical function may include converting a trigonometric function calculation from the range [-π, π] to a signed 2 trigonometric representation within the range [-1, 1].

Another aspect of this disclosure features a method comprising: obtaining primitive data for each of a plurality of primitives corresponding to an object in three-dimensional (3D) space; calculating a first electromagnetic (EM) field contribution from a first primitive among the plurality of primitives to each of a plurality of elements of a display; and calculating a second EM field contribution from a second primitive among the plurality of primitives to each of a plurality of elements of a display. The calculation of the first EM field contribution from the first primitive is at least partially parallel to the calculation of the second EM field contribution from the second primitive.

In some implementations, calculating the first EM field contribution from a first primitive to a first element of multiple elements is parallel to calculating the second EM field contribution from a second primitive to the first element of multiple primitives. The method may include calculating the respective EM field contributions from each of the multiple primitives to each of the multiple elements. Each EM field contribution calculation can eliminate the need to extend the object's geometry to multiple elements, apply visibility tests before packing wavefronts, and make decisions or communicate between parallel calculations for different primitives. Each EM field contribution calculation can be configured to cause at least one of the following: optimizing parallel calculations for different primitives for speed, cost, size, or energy; reducing the delay between initiating drawing and the display-ready result; improving accuracy using fixed-point representation; and optimizing calculation speed by optimizing mathematical functions.

In some implementations, the method further includes representing values using fixed-point representation during computation. Representing values using fixed-point representation can proceed without at least one of the following: denormalizing floats for gradual underflow, handling NaN results from operations including division by zero, changing floating-point rounding modes, and raising floating-point exceptions in the operating system.

In some implementations, the method further includes accumulating the EM field contributions for each of the elements by adding the second EM field contribution for each element to the first EM field contribution for each element.

In some implementations, the method further includes generating a control signal for each of a plurality of elements based on the sum of the EM field contributions from a plurality of primitives to the element, wherein each control signal is for adjusting at least one property of the element based on the sum of the EM field contributions from the plurality of primitives to the element.

In some implementations, the method further includes scaling the first primitive adjacent to the second primitive by a predetermined coefficient such that the reconstruction of the first primitive does not overlap with the reconstruction of the second primitive. The predetermined coefficient can be determined at least in part on the resolution of the display. The method may further include obtaining primitive data for each of a plurality of primitives, wherein the primitive data for each of the plurality of primitives includes coordinate information for each primitive in a 3D coordinate system, and determining new coordinate information for each of the first primitives based on the coordinate information for each of the first primitives and the predetermined coefficient. The method may further include determining the EM field contribution from the first primitive to each of a plurality of elements based on the new coordinate information for each of the first primitives. The method may further include scaling the second primitive by a predetermined coefficient. The first and second primitives may share a common part, and scaling the first primitive includes scaling the common part of the first primitive. Scaling the first primitive may also include scaling the first primitive in a predetermined direction.

Another aspect of this disclosure features a method comprising: obtaining primitive data for each of several primitives corresponding to an object in three-dimensional (3D) space; scaling the first primitive adjacent to the second primitive by a predetermined coefficient using the respective primitive data for the first and second primitives; and updating the respective primitive data for the first primitive based on the scaling result.

In some implementations, each primitive data of multiple primitives includes the coordinate information of the primitive in a 3D coordinate system, and updating each primitive data includes determining the new coordinate information of the first primitive based on the coordinate information of the first primitive and predetermined coefficients.

In some implementations, a predetermined coefficient is determined such that the reconstruction of the first primitive does not overlap with the reconstruction of the second primitive in 3D space.

In some implementations, scaling is performed such that the gap between the reconstruction of the first and second primitives in 3D space is large enough to separate the first and second primitives and minimize overlapping effects, while being small enough to make the reconstruction appear seamless.

In some implementations, a predetermined coefficient is determined at least partially based on the display resolution, or based on the actual or assumed distance from the viewer to the display, or the z-depth of the primitives in the display's 3D space.

In some implementations, the method further includes storing updated primitive data for the first primitive in a buffer.

In some implementations, scaling is performed during the rendering process of an object to retrieve the primitive data for each of multiple primitives.

In some implementations, the method further includes transmitting updated primitive data for multiple primitives to a controller, which is configured to determine, based on the updated primitive data for the multiple primitives, the respective electromagnetic (EM) field contribution from each of the multiple primitives to each of the multiple elements of the display.

In some implementations, the method further includes determining the EM field contribution from the first primitive to each of the multiple elements of the display, based on the updated primitive data of the first primitive.

In some implementations, the method further includes scaling a second primitive by a predetermined coefficient.

In some implementations, the first and second primitives share a common part, and scaling the first primitive includes scaling the common part of the first primitive.

In some implementations, scaling the first primitive includes scaling the first primitive in a predetermined direction.

In some implementations, scaling a first primitive includes scaling a first portion of the first primitive by a first predetermined coefficient and scaling a second portion of the second primitive by a second predetermined coefficient, wherein the first predetermined coefficient is different from the second predetermined coefficient.

Another aspect of this disclosure features a method comprising: obtaining multiple discrete cosine transform (DCT) weights of an image mapped onto a specific surface of a particular primitive among a plurality of primitives corresponding to an object in three-dimensional (3D) space; and determining the respective EM field contributions from the particular primitive to each of a plurality of elements of the display by taking into account the effects of the multiple DCT weights of the image.

In some implementations, the method further includes determining the resolution of an image mapped onto a specified surface of a particular primitive, and determining multiple DCT weights of the image based on the resolution.

In some implementations, the method further includes decoding the DCT weights of the image to obtain the respective DCT amplitude for each pixel of the image.

In some implementations, the method further includes storing the values associated with the DCT amplitude of each pixel in the image, along with the primitive data of a particular primitive. Determining each EM field contribution may include calculating the respective EM field contributions from a particular primitive to each of multiple elements using the values associated with the DCT amplitude of each pixel in the image.

In some implementations, the method further includes selecting specific DCT terms to be included in the determination of each EM field contribution, each of which has a DCT weight higher than a predetermined threshold.

Another aspect of this disclosure features a method for obtaining information about a given primitive and its occluders, wherein the given primitive is located within a plurality of primitives corresponding to an object in three-dimensional (3D) space, and for determining one or more specific elements of a plurality of display elements that do not contribute to the reconstruction of the given primitive as an effect of the occluder.

In some implementations, the method further includes storing information about a specific element along with information about a given primitive and occluder.

In some implementations, the decision is made during the rendering process of an object to retrieve primitive data for multiple primitives.

In some implementations, the method further includes transmitting stored information of a particular element, along with information of a given primitive and occluder, to a controller configured to calculate the electromagnetic (EM) contributions of multiple primitives to multiple elements of a display.

In some implementations, the method further includes generating the sum of electromagnetic (EM) field contributions from multiple primitives to one of the specific elements by excluding the EM field contribution from a given primitive to one of the specific elements for each of the specific elements.

In some implementations, the method further includes generating the sum of the EM field contributions from multiple primitives to each of several elements other than a specific element.

In some implementations, the method further includes masking the EM field contribution of a particular element to a given primitive.

In some implementations, determining one or more specific elements includes connecting a given primitive to the endpoints of an occluder, extending the connection to a display and determining the intersection of the connection and the display, and determining that a specific range defined by the intersection is a specific element that does not contribute to the reconstruction of the given primitive by the effect of the occluder.

Another aspect of the present invention is characterized by a method for obtaining information on a given primitive and its occluders, wherein the given primitive is located within a plurality of primitives corresponding to an object in three-dimensional (3D) space, and for each of a plurality of elements of a display, determining which parts of the given primitive do not contribute to the element's electromagnetic (EM) field as an effect of the occluder.

In some implementations, the method further includes storing information about each part of a given primitive, along with information about the given primitive and its occluder.

In some implementations, the decision is made during the rendering process of an object to retrieve primitive data for multiple primitives.

In some implementations, the method further includes transmitting the stored information of each part of a given piece of information, along with information of a given primitive and occluder, to a controller configured to calculate the electromagnetic (EM) contributions to multiple elements of a display for multiple primitives.

In some implementations, the method further includes masking the EM field contribution of each of the multiple elements to each part of a given primitive.

In some implementations, the method further includes generating a sum of the EM field contributions from multiple primitives to an element by subtracting the EM field contribution from each part of a given primitive to the element for each of the multiple elements. Generating a sum of the EM field contributions from multiple primitives to an element may include subtracting the EM contribution from each part of a given primitive to the element from the sum of the EM field contributions from multiple primitives to an element, without the effect of an occluder. Generating a sum of the EM field contributions from multiple primitives to an element may include summing the EM field contributions from one or more other parts of a given primitive to the element, where each part and one or more other parts form a given primitive.

In some implementations, determining which parts of a given primitive do not contribute to the EM field of an element as an effect of the occluder includes connecting the element to the endpoints of the occluder, determining the intersections of the connections and the given primitive, and determining which parts of the given primitive enclosed by the intersections are the parts of the given primitive that do not contribute to the EM field of the element as an effect of the occluder.

Another aspect of this disclosure features a method comprising: obtaining primitive data for each of a plurality of primitives corresponding to an object in three-dimensional (3D) space; obtaining geometric specular information for each of the plurality of primitives; and storing the primitive data and geometric specular information for each of the plurality of primitives.

In some implementations, the geometric specular information for each of several primitives includes the reflectivity of the primitive's surface at the viewing angle.

In some implementations, the method further includes determining the respective EM field contributions from each of several primitives to each of several elements of the display by considering the respective geometric specular information for each primitive.

Another aspect of this disclosure features a method comprising: acquiring graphic data containing primitive data for a plurality of primitives corresponding to an object in three-dimensional (3D) space; determining the electromagnetic (EM) field contribution to each of the plurality of elements of a display by calculating the EM field propagation from the primitive to the element in a 3D coordinate system for each of the plurality of primitives; generating a sum of the EM field contributions from the plurality of primitives to the element for each of the plurality of elements; transmitting a control signal to each of the plurality of elements, wherein the control signal modulates at least one characteristic of the element based on the sum of the EM field contributions to the element; and transmitting a timing control signal to an illuminator to illuminate the display with light, such that light is caused by the modulated elements of the display to form a volume light field corresponding to an object.

Another aspect of this disclosure features a method comprising: modifying each of a plurality of elements of a display by a predetermined calibration value; applying the modified control signals to the plurality of elements of the display; measuring the output of light incident on the display; and evaluating the predetermined calibration value based on the measurement of the light output.

In some implementations, the predetermined calibration value is the same for each of the multiple elements.

In some implementations, the method further includes converting the respective control signals of multiple elements using a digital-to-analog converter (DAC), and modifying the respective control signals for multiple elements includes modifying the digital signals of each control signal by a predetermined calibration value.

In some implementations, a given value includes multiple bits.

In some implementations, the method further includes adjusting a predetermined calibration value based on the evaluation results. Adjusting the predetermined calibration value may include modifying one or more values of a plurality of bits. Adjusting the predetermined calibration value may also include determining a combination of values for a plurality of bits based on the predetermined calibration value and another calibration value determined from a previous evaluation.

In some implementations, the light output includes a phase change of light, or an intensity difference between the light output and the background.

In some implementations, the control signal for each element is determined based on the sum of the electromagnetic (EM) field contributions from multiple primitives corresponding to the object in 3D space to the element.

Another aspect of this disclosure is a method for obtaining, for each of a plurality of elements of a display, the respective sums of electromagnetic (EM) field contributions from a plurality of primitives in three-dimensional (3D) space, wherein the plurality of primitives correspond to objects in 3D space; obtaining; applying the respective mathematical transformations to the respective sums of EM field contributions for each element to obtain the respective transformed sums of EM field contributions for each element; determining the respective control signals based on the respective transformed sums of EM field contributions for each element; and modulating the characteristics of the elements based on the determined respective control signals for each element.

In some implementations, the method further includes introducing light incident on multiple elements of a display, measuring a first output of light, and adjusting one or more coefficients of the respective mathematical transformations of the multiple elements based on the measurement of the first output of light. The method may further include changing the depth of the holographic pattern corresponding to an object, taking the display into consideration, measuring a second output of light, and adjusting one or more coefficients of the respective mathematical transformations based on the first and second outputs. The method may further include changing a plurality of primitives corresponding to a first holographic pattern to a second plurality of primitives corresponding to a second holographic pattern, measuring a second output of light, and adjusting one or more coefficients of the respective mathematical transformations based on the first and second outputs. The first and second holographic patterns may correspond to objects. The second holographic pattern may correspond to a second object different from the object associated with the first holographic pattern. The first light output can be measured by an imaging sensor (e.g., a point sensor, a spatially integrated sensor, or a three-dimensional sensor such as a light field sensor). The imaging sensor can be configured to use a machine vision algorithm to determine what is being displayed and calculate a fit parameter. Each of the first and second holographic patterns may include a grid of dots or other reference elements, and the fit parameter is at least one of the following: how close the dots or other reference elements are together; how close the dots or other reference elements are to the color and intensity of the intended positions; how well the dots or other reference elements are centered relative to the intended positions; and how distorted the dots or other reference elements are.

In some implementations, mathematical transformations are derived from Zernike polynomials.

In some implementations, the mathematical transformation for multiple elements varies element by element.

In some implementations, the method further includes reproducing a known sample set of colors and intensities by illuminating a display, measuring the output light using a colorimetric device that can be calibrated to a CIE standard observer curve, and defining the output light of the display within a color space such as the CIE color space. The method may further include determining the deviation of the defined output light values from known standard values, adapting the illumination to the display, or adapting the generation of output colors and intensities by the display to align them back to a conformity with, for example, a standard or desired value.

Another aspect of this disclosure features a method comprising: determining the cell gap of a liquid crystal (LC) display based on the pitch of the display elements of the LC display; and calculating the minimum birefringence of an LC mixture based on the cell gap and a predetermined delay of the LC display.

In some implementations, the method further includes improving the switching speed of an LC display by keeping the birefringence of the LC mixture above a minimum value. Improving the switching speed may include at least one of increasing the dielectric anisotropy of the LC mixture and decreasing the rotational viscosity of the LC mixture.

In some implementations, the LC display includes a liquid crystal on silicon (LCOS or LCoS) device having a silicon backplane.

In some implementations, the LC display includes a liquid crystal layer, a transparent conductive layer located above the liquid crystal layer as a common electrode, and a backplane having multiple metal electrodes located above or electrically close to the bottom of the liquid crystal layer, each of which is isolated from the others, and the backplane is configured to control the voltage of each of the multiple metal electrodes.

Another aspect of this disclosure features a display comprising a backplane and a plurality of display elements on the backplane, wherein at least two of the plurality of display elements are of different sizes.

In some implementations, at least two of the display elements, the larger one, are equipped with a buffer, while at least two of the display elements, the smaller one, is not equipped with a buffer. The larger display element can be connected to a first plurality of display elements by conductive wires, and the buffer is configured to buffer the voltage applied to the conductive wires so that the voltage is applied only to the second plurality of display elements within the first plurality of display elements, with some of the second plurality of display elements being smaller than some of the first plurality of display elements.

In some implementations, the buffer comprises either an analog circuit in the form of transistors or a digital circuit in the form of logic gates.

In some implementations, the size distribution of multiple display elements is substantially identical to the size of the smaller of at least two display elements.

In some implementations, the display is configured as a liquid crystal on silicon device.

Another aspect of this disclosure features a display comprising a backplane and a plurality of display elements on the backplane, wherein at least two of the plurality of display elements have different shapes.

In some implementations, the backplane includes a circuit for each of the display elements, and each circuit for at least two display elements has a shape corresponding to the different shapes of at least two display elements.

In some implementations, the size distribution of multiple display elements is substantially identical to a predetermined size.

In some implementations, the display is configured as a liquid crystal on silicon device.

Another aspect of this disclosure features a method comprising: acquiring graphic data containing primitive data for a plurality of primitives corresponding to an object in three-dimensional (3D) space; determining the electromagnetic (EM) field contribution to each of the plurality of elements of a display by calculating the EM field propagation from the primitive to the element in a 3D coordinate system for each of the plurality of primitives; generating a sum of the EM field contributions from the plurality of primitives to the element for each of the plurality of elements; transmitting a control signal to each of the plurality of elements, wherein the control signal modulates at least one characteristic of the element based on the sum of the EM field contributions to the element; and transmitting a timing control signal to an illuminator to illuminate the display with light, such that light is caused by the modulated elements of the display to form a volume light field corresponding to an object.

Other embodiments of the model include corresponding computer systems, devices, and computer programs recorded on one or more computer storage devices, each configured to perform the actions of the method. The configuration of one or more computer systems to perform a specific operation or action means that the systems have installed software, firmware, hardware, or a combination thereof that causes the systems to perform the operation or action during operation. The configuration of one or more computer programs to perform a specific operation or action means that one or more programs, when executed by a data processing device, contain instructions that cause the device to perform the operation or action.

Another aspect of this disclosure features a device comprising one or more processors and a non-temporary computer-readable storage medium that communicates with the one or more processors, is executable by the one or more processors, and stores instructions that, during such execution, cause the one or more processors to perform one or more of the methods disclosed herein.

Another aspect of this disclosure features a non-temporary, computer-readable storage medium that is executable by one or more processors and, during such execution, stores instructions causing one or more processors to perform a method according to one or more of the methods disclosed herein.

Another aspect of this disclosure features a display comprising a plurality of elements and a controller coupled to the display and configured to perform one or more of the methods disclosed herein. The controller may include a plurality of computing units, each of which is configured to perform operations on one or more primitives of a plurality of primitives corresponding to objects in three-dimensional (3D) space. In some implementations, the controller is coupled locally to the display, and each computing unit is coupled to one or more respective elements of the display and configured to transmit their respective control signals to each of the one or more respective elements. The computing units may be configured to operate in parallel.

The controller may include at least one of the following: an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), a programmable gate array (PGA), a central processing unit (CPU), a graphics processing unit (GPU), or a standard or custom computing cell. The display may include a spatial light modulator (SLM) including a digital micromirror device (DMD) or a liquid crystal on silicon (LCOS or LCoS) device. The display may be configured to be phase-modulated, amplitude-modulated, or both phase- and amplitude-modulated. The controller may be coupled to the display via a memory buffer.

In some implementations, the system includes an irradiator positioned adjacent to the display and configured to emit light onto the display. The irradiator may be coupled to a controller and configured to be turned on/off based on control signals from the controller.

In some cases, the irradiator is coupled to a controller via a memory buffer configured to control the amplitude or brightness of one or more light-emitting elements within the irradiator. The memory buffer for the irradiator may be smaller in size than the memory buffer for the display. Some of the light-emitting elements within the irradiator may be smaller than some of the elements in the display. The controller may be configured to operate one or more of the light-emitting elements of the irradiator simultaneously or sequentially.

The irradiator may be a coherent, semi-coherent, or incoherent light source. In some implementations, the irradiator is configured to emit white light, and the display is configured to diffract the white light into light of different colors. In some implementations, the irradiator includes two or more light-emitting elements, each configured to emit light of a different color. The controller may be configured to sequentially modulate the display with information associated with a first color during a first period, and to modulate the display with information associated with a second color during a second consecutive period. The controller may be configured to control the irradiator so that the first light-emitting element emits light of the first color during the first period, and the second light-emitting element emits light of the second color during the second period, in a sequential manner.

In some implementations, the irradiator is positioned in front of the display surface and configured to emit light onto the display surface at an incident angle in the range of 0 to 90 degrees, and the emitted light is diffracted from the display. In some cases, the light emitted from the irradiator includes collimated light. In some cases, the light emitted from the irradiator includes divergent light. In some cases, the light emitted from the irradiator includes focused light. In some cases, the light emitted from the irradiator includes semi-collimated light.

In some implementations, the irradiator is positioned behind the back of the display and is configured to emit divergent collimated, semi-collimated, or focused light onto the back of the display, which is transmitted through the display and diffracted from the front of the display.

In some implementations, the illuminator includes a light source configured to emit light, and a waveguide coupled to the light source and positioned adjacent to the display, wherein the waveguide is configured to receive the light emitted from the light source and guide the emitted light to the display. In some cases, the light from the light source is coupled to the waveguide from the side cross-section of the waveguide via an optical coupler. In some cases, the light source and waveguide are integrated in a planar configuration and positioned on the surface of the display. The waveguide can be configured to guide the light to uniformly illuminate the display.

In some cases, the waveguide is positioned on the back of the display, or optically close to it, and light is guided to pass through the display, transmitted, and diffracted from the front of the display. The controller can be positioned on the back of the waveguide. In some cases, the waveguide or light guide is positioned on the front of the display, or optically close to the front of the display, and light is guided to enter the front of the display, passed through the front, reflected backward, and diffracted.

Another aspect of the present disclosure is an integrated circuit comprising a display including an array of elements and an array of computing units, each of which computing units is coupled to one or more of the elements of the display, and which calculates the electromagnetic (EM) field contribution to each of the element arrays from at least one primitive among a plurality of primitives, and for one or more of the elements,
The system comprises an integrated circuit configured to generate the sum of the respective EM field contributions from multiple primitives to an element.

Each computing unit can be configured to receive computed EM field contributions from other computing units in the array of computing units to each of one or more elements from other primitives, and to generate the sum of each EM field contribution by adding the received computed EM field contributions from other primitives to each of the one or more elements.

Each computing unit can be configured to generate a control signal for each of the one or more elements, based on the sum of their respective EM field contributions to the elements, to modulate at least one characteristic of the elements.

In some implementations, the integrated circuit includes an accumulator configured to store the cumulative result of the calculated EM field contributions from multiple primitives to each of the elements of the display. The integrated circuit may be configured to clear the accumulator at the start of the calculation operation. In some examples, the integrated circuit includes a memory buffer for each of the elements, and the integrated circuit may be configured to accumulate the calculated EM field contributions from multiple primitives to the elements, obtain the respective sums of the EM field contributions as the final accumulation result in each accumulator, and transfer the final accumulation result from each accumulator to the respective memory buffer of the elements.

In some implementations, the system further includes an illuminator positioned between the integrated circuit and the display, configured to receive control signals from the integrated circuit and to illuminate the display based on those signals, and the integrated circuit, illuminator, and display can be integrated as a single unit.

Another aspect of this disclosure features a system including a computing device configured to generate data containing primitive data for each of several primitives corresponding to an object in three-dimensional (3D) space, and a system as disclosed herein. The system is configured to receive graphic data from the computing device and to process the graphic data to present the object in 3D space. The computing device may include an application programming interface (API) configured to create primitives with each primitive data by rendering a computer-generated (CG) model of the object.

Another aspect of this disclosure is:
The optical device is characterized by comprising a first optical diffraction component, a second optical diffraction component, and a color-selective polarizer between the first and second optical diffraction components. When a first light beam containing light of a first color in a first polarization state is incident on a first optical diffraction component, the first optical diffraction component diffracts the light of a first color in a first polarization state; when a second light beam containing light of a second color in a second polarization state is incident on a color-selective polarizer, the color-selective polarizer converts the second light beam into a third light beam containing light of a second color in a first polarization state, the second color being different from the first color, the second polarization state being different from the first polarization state; when the third light beam is incident on the second optical diffraction component, the second optical diffraction component diffracts the light of a second color in a first polarization state; and the diffraction efficiency of the first optical diffraction component in diffracting the light of a second color in a second polarization state is substantially smaller than the diffraction efficiency of the first optical diffraction component in diffracting the light of a first color in a first polarization state.

Another aspect of the present disclosure features an optical device comprising a first optical diffraction component, a second optical diffraction component, and a color-selective polarizer between the first optical diffraction component and the second optical diffraction component. When light of a first color is incident on the first optical diffraction component at a first angle of incidence and in a first polarization state, the first optical diffraction component diffracts the light of the first color at a first diffraction angle with a first diffraction efficiency. When light of a second color, different from the light of the first color, is incident on the first optical diffraction component at a second angle of incidence and in a second polarization state different from the first polarization state, the first optical diffraction component diffracts the light of the second color with a diffraction efficiency substantially lower than the first diffraction efficiency. When light of a second color in a second polarization state is incident on a color-selective polarizer, the color-selective polarizer rotates the polarization state of the light of the second color from the second polarization state to the first polarization state. When light of a second color is incident on the second optical diffraction component at a second angle of incidence and in a first polarization state, the second optical diffraction component diffracts the light of the second color at a second diffraction angle with a second diffraction efficiency.

Another aspect of this disclosure features an optical device comprising: a first optical diffraction component configured to (i) diffract light of a first color in a first polarization state incident at a first angle of incidence with a first diffraction efficiency at a first diffraction angle; and (ii) diffract light of a second color in a second polarization state incident at a second angle of incidence with a diffraction efficiency substantially lower than the first diffraction efficiency; a color-selective polarizer configured to rotate the polarization state of light of a second color in a second polarization state incident on the color-selective polarizer from the second polarization state to the first polarization state; and a second optical diffraction component configured to diffract light of a second color in a first polarization state incident at a second angle of incidence with a second diffraction efficiency at a second diffraction angle, wherein the color-selective polarizer is located between the first and second optical diffraction components.

In some implementations, the second optical diffraction component is configured to diffract light of the first color in the second polarization state at a first incident angle with a diffraction efficiency substantially lower than that of the second diffraction efficiency.

In some implementations, the first optical diffraction component, the color-selective polarizer, and the second optical diffraction component are sequentially stacked such that light of the first color and light of the second color are incident on the first optical diffraction component before the second optical diffraction component.

In some implementations, the optical device further includes a third optical diffraction component and a second color-selective polarizer between the second and third optical diffraction components. The second color-selective polarizer is configured to rotate the polarization state of light of a third color from a second polarization state to a first polarization state when light of a third color is incident on the second color-selective polarizer in a second polarization state. The third optical diffraction component is configured to diffract light of a third color at a third diffraction angle and with a third diffraction efficiency when light of a third color is incident on the third optical diffraction component at a third incidence angle and in a first polarization state.

In some implementations, a color-selective polarizer is configured to rotate the polarization state of light of a first color from a first polarization state to a second polarization state, while a second color-selective polarizer is configured to rotate the polarization state of light of a second color from a first polarization state to a second polarization state without rotating the polarization state of light of the first color.

In some implementations, the system further includes a third color-selective polarizer configured to rotate the polarization states of the first and second colored light from the second polarization state to the first polarization state, without rotating the polarization state of the third colored light. The third optical diffraction component lies between the second and third color-selective polarizers.

In some implementations, the third optical diffraction component is configured to diffract each of the first and second colored light incident in the second polarization state with a diffraction efficiency substantially lower than that of the third diffraction efficiency. The first optical diffraction component is configured to diffract the third colored light incident in the second diffraction state with a diffraction efficiency substantially lower than that of the first diffraction efficiency, and the second optical diffraction component is configured to diffract each of the first and third colored light incident in the second polarization state with a diffraction efficiency substantially lower than that of the second diffraction efficiency.

In some implementations, the second color-selective polarizer includes a pair of first and second sub-polarizers. The first sub-polarizer is configured to rotate the polarization state of the second color light from the first to the second polarization state, without rotating the polarization states of the first and third color light respectively. The second sub-polarizer is configured to rotate the polarization state of the third color light from the second to the first polarization state, without rotating the polarization states of the first and second color light respectively.

In some implementations, the optical device further comprises a fourth color-selective polarizer configured to rotate the polarization state of the first color of light from the second polarization state to the first polarization state, without rotating the polarization states of the second and third color of light, and the first optical diffraction component is located between the fourth color-selective polarizer and the color-selective polarizer.

In some implementations, each of the first, second, and third optical diffraction components includes a holographic grating formed on a recording medium. The recording medium may contain a photosensitive polymer. The recording medium may be optically transparent. Each holographic grating can be fixed to the recording medium.

In some implementations, each of the first, second, and third optical diffraction components includes a carrier film attached to the recording medium. Each of the first, second, and third optical diffraction components may also include a diffraction substrate attached to the other side of the recording medium opposite to the carrier film.

In some cases, the carrier film of the first optical diffraction component is attached to the first side of the color-selective polarizer, the diffraction substrate of the second optical diffraction component is attached to the second opposite side of the color-selective polarizer, the carrier film of the second optical diffraction component is attached to the first side of the second color-selective polarizer, and the diffraction substrate of the second optical diffraction component is attached to the second opposite side of the second color-selective polarizer.

In some implementations, the optical device further includes a substrate, and the first optical diffraction component is located between the substrate and a color-selective polarizer. In some implementations, the optical device further includes an anti-reflective coating on the surface of the substrate. In some implementations, the optical device includes a front and a back surface, with light of a first color and light of a second color incident on the front surface, and the optical device further includes an anti-reflective coating on the back surface.

In some implementations, the optical device includes a plurality of optical components, each comprising a first optical diffraction component, a color-selective polarizer, and a second optical diffraction component, wherein two adjacent optical components are mounted together through a refractive index matching material.

In some implementations, each of the first optical diffraction component and the second optical diffraction component includes a Bragg grating formed in the recording medium, and each Bragg grating includes a plurality of fringe planes, each having a fringe inclination angle _θt and a fringe spacing Λ perpendicular to the fringe planes in the volume of the recording medium.

In some cases, each Bragg grating has a diffraction angle θ _m when the angle of incidence to the recording medium is the on-Bragg angle,
,
It is structured to satisfy Bragg's formula as follows:
In the formula, λ represents the wavelength of light of a certain color in a vacuum, n represents the refractive index in the recording medium, _θm represents the m-th order Bragg angle of diffraction in the recording medium, and _θt represents the fringe slope in the recording medium.

In some cases, the first and second angles of incidence are substantially identical to the Ombrag angle, and the first and second diffraction angles are substantially identical to the first Bragg angle.

In some cases, the fringe inclination angle of each Bragg grid is substantially identical to 45 degrees.

In some cases, the thickness of the recording medium is more than an order of magnitude larger than the fringe spacing. The thickness of the recording medium can be approximately 30 times greater than the fringe spacing.

In some cases, the first diffraction angle and the second diffraction angle are substantially identical to each other.

In some cases, the first and second diffraction angles are in the range of -10 to 10 degrees. The first and second diffraction angles may be substantially identical to 0 degrees. The first and second diffraction angles may be in the range of -7 to 7 degrees. The first and second diffraction angles may be substantially identical to 6 degrees.

In some cases, the first and second angles of incidence are in the range of 70 to 90 degrees. The first and second angles of incidence may be substantially identical to each other.

In some cases, the first polarization state is s-polarization, and the second polarization state is p-polarization.

In some implementations, the first optical diffraction component is configured to diffract light of a second color incident in a second polarization state with a diffraction efficiency at least one order of magnitude smaller than the first diffraction efficiency.

In some implementations, the color-selective polarizer is configured not to rotate the polarization state of light of the first color.

In some implementations, the optical device further includes a second color-selective polarizer configured to rotate the polarization state of a first color of light from a second polarization state to a first polarization state without rotating the polarization state of a second color of light, wherein the first optical diffraction component is located between the second color-selective polarizer and another color-selective polarizer.

In some implementations, the first optical diffraction component includes a first diffraction structure, the second optical diffraction component includes a second diffraction structure, the optical device includes a first reflective layer and a second reflective layer, and the first reflective layer is located between the first diffraction structure and the second diffraction structure.
The second diffraction structure is located between the first and second reflective layers, and the first diffraction structure is
i) to diffract first-order and zero-order first-color light incident on the first diffraction structure at a first angle of incidence, wherein the first-order light is diffracted at the first diffraction angle and the zero-order light is transmitted at the first angle of incidence; and ii) to transmit second-color light incident on the first diffraction structure at a second angle of incidence, wherein the first reflective layer is configured to i) completely reflect first-color light incident on the first reflective layer at the first angle of incidence, and ii The second diffraction structure is configured to transmit light of a second color incident on the first reflection layer at a second incidence angle, and the second diffraction structure is configured to diffract primary and zeroth order light of a second color incident on the second diffraction structure at a second incidence angle, with the primary light being diffracted at the second diffraction angle and the zeroth order light being transmitted at the second incidence angle, and the second reflection layer is configured to completely reflect light of a second color incident on the second reflection layer at the second incidence angle.

Another aspect of the present disclosure features an optical device comprising a first optical diffraction component including a first diffraction structure, a second optical diffraction component including a second diffraction structure, a first reflective layer, and a second reflective layer. The first reflective layer is located between the first diffraction structure and the second diffraction structure, and the second diffraction structure is located between the first reflective layer and the second reflective layer. When light of a first color is incident on the first diffraction structure at a first angle of incidence, the first diffraction structure diffracts first-order and zero-order light of the first color, the first order being diffracted at a first diffraction angle and the zero-order being transmitted at a first angle of incidence. When light of a second color is incident on the first diffraction structure at a second angle of incidence, the first diffraction grating transmits light of the second color at a second angle of incidence, and the first reflective layer transmits light of the first color at a first angle of incidence. When light of the first color is incident on the first reflective layer, the first reflective layer completely reflects the light of the first color. When light of the second color is incident on the first reflective layer at a second angle of incidence, the reflective layer transmits the light of the second color at a second angle of incidence. When light of the second color is incident on the second diffraction structure at a second angle of incidence, the second diffraction structure diffracts the primary and zero-order light of the second color, with the primary being diffracted at the second diffraction angle and the zero-order being transmitted at the second angle of incidence. When light of the second color is incident on the second reflective layer at a second angle of incidence, the second reflective layer completely reflects the light of the second color.

Another aspect of the present disclosure is a first optical diffraction component comprising a first diffraction structure configured to i) diffract primary and zero-order light of a first color incident on the first diffraction structure at a first angle of incidence, wherein the primary light is diffracted at the first angle of incidence and the zero-order light is transmitted at the first angle of incidence; and ii) transmit second color light incident on the first diffraction structure at a second angle of incidence; and configured to i) completely reflect first color light incident on a first reflective layer at a first angle of incidence; and ii) transmit second color light incident on the first reflective layer at a second angle of incidence. The optical device comprises: a first reflective layer; a second diffraction structure configured to diffract primary and zero-order light of a second color incident at a second incidence angle, wherein the primary light is diffracted at the second diffraction angle and the zero-order light is transmitted at the second incidence angle; and a second reflective layer configured to completely reflect light of a second color incident at a second incidence angle, wherein the first reflective layer is located between the first and second diffraction structures, and the second diffraction structure is located between the first and second reflective layers.

Another aspect of the present disclosure features an optical device comprising: a first optical diffraction component including a first diffraction structure configured to diffract light of a first color having a first angle of incidence at a first diffraction angle; a second optical diffraction component including a second diffraction structure configured to diffract light of a second color having a second angle of incidence at a second diffraction angle; a first reflective layer configured to completely reflect light of a first color having a first angle of incidence and to transmit light of a second color having a second angle of incidence; and a second reflective layer configured to completely reflect light of a second color having a second angle of incidence, wherein the first reflective layer is located between the first and second diffraction structures, and the second diffraction structure is located between the first and second reflective layers.

In some implementations, the optical device further includes a color-selective polarizer between a first diffracting structure and a second diffracting structure. The first diffracting structure i) diffracts light of a first color in a first polarization state incident at a first angle of incidence with a first diffraction efficiency, and ii) diffracts light of a second color in a second polarization state incident at a second angle of incidence.
It can be configured to diffract at a diffraction efficiency substantially lower than the first diffraction efficiency. The color-selective polarizer is
The polarization state of the second color of light in the second polarization state incident on a color-selective polarizer is defined as follows:
The system can be configured to rotate from a second polarization state to a first polarization state. The second diffraction structure can be configured to diffract light of a second color in the first polarization state, incident at a second incidence angle, with a second diffraction efficiency.

In some implementations, the optical device further includes a side, and a light absorber mounted on the side, configured to absorb fully reflected light of a first and a second color.

In some implementations, the first reflective layer is configured to have a lower refractive index than the layer of the first optical diffraction component directly adjacent to the first reflective layer. Therefore, light of a first color with a first incident angle is completely reflected by the interface between the first reflective layer and the layer of the first optical diffraction component without completely reflecting light of a second color with a second incident angle.

In some implementations, the first optical diffraction component includes a first carrier film and a first diffraction substrate attached to both sides of the first diffraction structure, wherein the first carrier film is closer to the second diffraction structure than the first diffraction substrate, and the first carrier film may include a first reflective layer.

In some implementations, the second optical diffraction component includes a second carrier film and a second diffraction substrate attached to both sides of the second diffraction structure, wherein the second diffraction substrate is closer to the first diffraction structure than the second carrier film, and the second reflective layer is attached to the second carrier film.

In some implementations, the optical device further includes a third optical diffraction component comprising a third diffraction structure configured to diffract primary and zero-order light of a third color incident at a third incidence angle to the third diffraction structure, wherein the primary light is diffracted at the third diffraction angle, the zero-order light is transmitted at the third incidence angle, and a second reflective layer is located between the second and third diffraction structures.

In some cases, the first and second reflective layers are configured to transmit light of a third color incident at a third angle of incidence.

In some implementations, the optical device further includes a third reflective layer configured to completely reflect light of a third color incident at a third angle of incidence to the third reflective layer.
A third diffraction structure exists between the second and third reflective layers.

In some implementations, the second optical diffraction component includes a second diffraction substrate and a second carrier film positioned on both sides of the second diffraction structure, the third optical diffraction component includes a third carrier film and a third diffraction substrate positioned on both sides of the third diffraction structure, and the second reflective layer is located between the second carrier film and the third carrier film.

In some implementations, each of the first and second diffraction structures includes a holographic grating formed on the recording medium. The recording medium may contain a photosensitive polymer. The recording medium may be optically transparent.

In some implementations, each of the first optical diffraction component and the second optical diffraction component includes a Bragg grating formed in the recording medium, and each Bragg grating includes a plurality of fringe planes perpendicular to the fringe plane in the volume of the recording medium, each having a fringe inclination angle _θt and a fringe spacing Λ.

In some implementations, each Bragg grating has a diffraction angle θ _m such that when the angle of incidence to the recording medium is the on-Bragg angle,
,
It is structured to satisfy Bragg's formula as follows:
In the formula, λ represents the wavelength of light of a certain color in a vacuum, n represents the refractive index in the recording medium, _θm represents the m-th order Bragg angle of diffraction in the recording medium, and _θt represents the fringe slope in the recording medium.

The first and second angles of incidence may be substantially identical to their respective Ombragg angles, and the first and second diffraction angles may be substantially identical to their respective primary Bragg angles.

In some implementations, the thickness of the recording medium is more than an order of magnitude larger than the fringe spacing. The thickness of the recording medium can be approximately 30 times greater than the fringe spacing.

In some cases, the first and second diffraction angles are substantially identical to each other. In some examples, each of the first and second diffraction angles lies in the range of -10 to 10 degrees. In some examples, each of the first and second diffraction angles is substantially identical to 0 degrees. In some examples, each of the first and second diffraction angles is substantially identical to 6 degrees.

In some cases, the first angle of incidence is different from the second angle of incidence. In some cases, the light of the first color has a smaller (or shorter) wavelength than the light of the second color, and the first angle of incidence of the light of the first color is larger (or longer) than the second angle of incidence of the light of the second color. In some cases, both the first and second angles of incidence are in the range of 70 to 90 degrees.

In some implementations, the optical device includes a plurality of components, including a first optical diffraction component and a second optical diffraction component, wherein two adjacent components among the plurality of components are attached together by an intermediate layer containing at least one of a refractive index matching material, OCA, UV-curing optical adhesive or thermosetting optical adhesive, or an optical contact material.

In some implementations, the second reflective layer includes an intermediate layer.

In some implementations, the optical device further includes a substrate having a back surface mounted on the front surface of a first optical diffraction component. The substrate may include sides angled with respect to the back surface and configured to receive light of multiple different colors at the sides. The angle between the sides and the back surface of the substrate may be 90 degrees or greater. The substrate may be configured so that light of multiple different colors is incident on the sides at an incident angle substantially the same as 0 degrees. In some cases, the substrate is wedge-shaped and includes an inclined front surface, and the angle between the front surface and the sides is less than 90 degrees.

Another aspect of this disclosure features a system comprising an irradiator configured to provide light of multiple different colors, and one of the optical devices described herein. The optical device is positioned adjacent to the irradiator and is configured to receive light of multiple different colors from the irradiator and to diffract the light of multiple different colors.

In some implementations, optical devices are configured to diffract light of multiple different colors at diffraction angles that are substantially identical to each other.

In some examples, each diffraction angle falls within the range of -10 degrees to 10 degrees.

In some implementations, the system further includes a controller coupled to the irradiator and configured to control the irradiator to provide each of several different colors.

In some implementations, the system further includes a display comprising multiple display elements, and the optical device is configured to diffract light of multiple colors toward the display.

In some implementations, the controller is coupled to the display and configured to transmit control signals to each of the multiple display elements for modulation of at least one characteristic of each display element.

In some implementations, the controller is configured to: acquire graphic data containing primitive data for multiple primitives corresponding to objects in three-dimensional space; determine the electromagnetic (EM) field contribution of each of the multiple primitives to each of the multiple display elements of the display; generate the sum of the EM field contributions from the multiple primitives to each of the multiple display elements; and generate a control signal for each of the multiple display elements based on the sum of the EM field contributions to the display elements.

Another aspect of this disclosure is a system comprising a display including a plurality of display elements and one of the optical devices described herein, wherein the optical device is configured to diffract light of a plurality of different colors toward the display.

In some implementations, the optical device and the display are arranged along a certain direction. The optical device includes a front and a back along the direction, and the display also includes a front and a back along the direction, with the front of the display spaced apart from the back of the optical device.

In some implementations, the front of the display is separated from the back of the optical device by a gap. At least one of the front of the display or the back of the optical device can be treated with an anti-reflective coating.

In some implementations, the system further includes a transparent protective layer on the back of the optical device.

In some implementations, the front of the display and the back of the optical device are joined together by an intermediate layer. The intermediate layer can be configured to have a refractive index lower than that of the optical device layer, such that each of the multiple colors of light transmitted by the optical device in zero order is completely reflected at the interface between the intermediate layer and the optical device layer.

In some implementations, the system further includes a cover (e.g., cover glass) on the front of the display, and the optical device is formed within the cover glass.

In some implementations, the optical device is configured to receive light of multiple colors at the front of the optical device.

In some implementations, the optical device includes a substrate in front of it and is configured to receive multiple colors of light on the side of the substrate that is angled relative to the back surface of the substrate.

In some implementations, the optical device includes at least one diffraction grating supported by a substrate and configured to diffract light of multiple different colors toward a display.

In some implementations, the substrate includes a container filled with a liquid having a refractive index lower than that of the diffraction grating recording medium.

In some implementations, the substrate is wedge-shaped and has a slanted front. The angle between the front and side may be less than 90 degrees.

In some implementations, the optical device is configured to receive multiple different portions of light of different colors along different optical paths within a substrate, and to diffract these different portions to illuminate different corresponding areas of a display. These different areas may include two or more of the lower, upper, left, and right regions of the display. The multiple different portions of light of different colors can be provided by different corresponding illuminators. The optical device can be configured to receive multiple different portions of light of different colors from different corresponding sides of the substrate.

In some examples, the optical device is configured to receive a first portion of light of multiple different colors from a first side of the substrate to the back of the optical device, diffract the first portion to illuminate a first area of the display, and receive a second portion of light of multiple different colors from a second side of the substrate to the front of the optical device, reflect the second portion backward against the back of the optical device, diffract the second portion to illuminate a second area of the display. The first and second sides may be the same side. The second portion of light of multiple different colors can be reflected by total internal reflection or a reflection grating within the optical device. The substrate may also include a partially reflective surface configured to separate the input light into a first portion and a second portion.

In some implementations, the optical device includes at least one diffraction grating positioned on the back of the optical device. The diffraction grating may include different sub-regions having different corresponding diffraction efficiencies. The diffraction grating can be configured to diffract a first portion of multiple different colored light incident on a first sub-region of the diffraction grating to illuminate a first region of the display, and further to reflect a second portion of multiple different colored light, reflected backward from the back of the optical device and incident on a second sub-region of the diffraction grating, back to the front of the optical device, and to diffract the second portion to illuminate a second different region of the display.

In some examples, the diffraction grating is configured such that the first and second diffracted portions on the first and second regions of the display have substantially the same optical power. The first and second regions of the display may have different reflectances associated with the first and second different diffraction efficiencies of the first and second sub-regions of the diffraction grating.

In some implementations, the diffraction grating includes multiple sub-regions that are tiled together. These sub-regions can be tiled along the horizontal direction.

In some cases, the edges of different sub-regions are configured to contact each other in an optically seamless manner. Different sub-regions can be formed by including one or more edge-defining elements in at least one optical path of the recording beam or object beam when recording each sub-region onto the recording medium, and these one or more edge-defining elements may include square apertures, rectangular apertures, or planar tile apertures.

In some cases, two adjacent sub-regions of the diffraction grating are in contact with the gap. The display may include multiple tiled display devices, and the gaps between adjacent sub-regions of the diffraction grating are aligned with the gaps between adjacent tiled display devices of the display.

In some cases, two adjacent, distinct subregions have an overlap.

In some implementations, diffraction gratings are mechanically formed using embossed structures, nanoimprinted structures, or self-assembled structures.

In some implementations, the display has a width along the horizontal direction and a height along the vertical direction, both of which are perpendicular to the direction, and the aspect ratio of width to height can be greater than 16:9.

In some implementations, the optical device is configured to diffract light of multiple different colors at diffraction angles that are substantially identical to each other. In some examples, each of the diffraction angles is in the range of -10 to 10 degrees.

In some implementations, the display is configured to diffract the diffracted color light backward through an optical device.

In some implementations, an area of the optical device covers an area of the display.

In some implementations, the system further includes an irradiator positioned adjacent to the optical device and configured to provide the optical device with light of multiple colors. The irradiator may include multiple light-emitting elements, each configured to emit light of a specific color.

In some implementations, the beam centers from multiple light-emitting elements may be offset from one another. The irradiator may be configured to provide a light beam having an elliptical or rectangular beam profile. The irradiator may be configured to provide a light beam with a specific polarization orientation. The irradiator may include one or more optical components configured to independently control the ellipticity and polarization orientation of each of several different colored lights.

In some implementations, the irradiator includes one or more optical components configured to control the uniformity of multiple different colored lights. These one or more optical components include an apodizing optical element or a profile converter.

In some implementations, the system includes one or more anamorphic optical elements or one or more cylindrical optical elements configured to increase the width of light of multiple different colors.

In some implementations, the system may further include a prism element between the irradiator and an optical device, configured to receive light of multiple different colors from its input surface, and one or more extension gratings adjacent to the exit surface of the prism element, each of which is configured to extend the beam profile of light of different corresponding colors by a coefficient in at least one dimension.

In some implementations, the system may further include one or more reflectors downstream of one or more expansion diffraction gratings, each of which is configured to reflect light of a particular color to an optical device. The tilt angle of each of the reflectors may be independently adjustable to ensure uniformity of diffraction from the optical device to the display.

The system may further include at least one color sensor or luminance sensor configured to detect one or more optical properties of the holographic light field formed by the system, and the tilt angle of one or more reflectors is adjustable based on the detected optical properties of the holographic light field. One or more optical properties may include luminance uniformity, color uniformity, or white point.

In some implementations, one or more reflectors are adjustable to compensate for changes in the alignment of the system's components.

In some implementations, the optical distance between one or more reflectors and an optical device is configured such that each of several different colors of light is reflected by the corresponding reflector without transmission through one or more other reflectors.

In some implementations, one or more reflectors are configured such that the light emitted from each of the reflectors comes from substantially different directions.

In some implementations, the angle between the prism element and the substrate of the optical device can be adjusted to tilt the position of the holographic light field formed by the system.

In some implementations, one or more expansion gratings are configured to collimate multiple different colored lights in one or two transverse directions, at least partially.

In some implementations, the system further includes a controller coupled to the irradiator and configured to control the irradiator to provide each of a plurality of colored lights. The controller may be coupled to a display and configured to transmit respective control signals to each of the plurality of display elements for modulation of at least one characteristic of the display elements.

In some implementations, the controller is configured to: acquire graphic data containing primitive data for multiple primitives corresponding to objects in three-dimensional space; determine the electromagnetic (EM) field contribution of each of the multiple primitives to each of the multiple display elements of the display; generate the sum of the EM field contributions from the multiple primitives to each of the multiple display elements; and generate a control signal for each of the multiple display elements based on the sum of the EM field contributions to the display elements.

In some implementations, the controller is configured to sequentially modulate the display with information associated with multiple colors of light over a series of periods, and to control the irradiator to sequentially emit each of the multiple colors of light into the optical device during each period of the series, such that each of the multiple colors of light is diffracted by the optical device toward the display and reflected by the modulated display elements of the display, forming a corresponding three-dimensional light field of each color for the object within each period.

In some implementations, the controller is configured to modulate the display so that the three-dimensional light field of each color appears entirely in front of the display, entirely behind the display, or partially in front of and partially behind the display.

In some cases, the display includes a spatial light modulator (SLM) containing a digital micromirror device (DMD) or a liquid crystal on silicon (LCOS) device.

In some implementations, the system further includes an optical polarizer placed between the display and the optical device, the optical polarizer configured to change the polarization state of multiple different colored lights.

In some implementations, the optical device includes an optical diffraction component configured to diffract light containing multiple different colors toward a display configured to diffract a portion of the light illuminating the display elements.

In some implementations, the optical device further includes an optical redirection component configured to transmit a portion of light to form a holographic scene and to redirect the display zero-order light away from the holographic scene in three-dimensional (3D) space, wherein the display zero-order light includes reflected light from the display.

In some implementations, the optical redirection component includes multiple redirection holographic gratings for the zero-order display light of multiple different colors, and each of the multiple redirection holographic gratings is configured to diffract the zero-order display light of each of the multiple different colors in its respective direction in 3D space at its respective diffraction angle.

In some implementations, the optical diffraction component is configured to diffract light of multiple different colors so as to redirect the zero-order light reflected from the display away from the holographic scene, thereby illuminating the display at an angle of approximately 0 ^° .

In some implementations, the ratio of the amount of display zero-order light in the holographic scene with suppression of optical diffraction and optical redirection components to the amount of display zero-order light in the holographic scene without suppression is less than 2%.

In some implementations, the optical redirection component includes a one-dimensional suppression grating, the holographic scene includes a band corresponding to the suppression of zero-order light in the display, and the system can be configured such that the band lies outside the viewer's field of view.

Another aspect of this disclosure features a system comprising: a display including a plurality of display elements; an optical device positioned adjacent to the display and configured to diffract light toward the display; and a controller connected to the display and configured to acquire graphic data including primitive data for a plurality of primitives corresponding to objects in three-dimensional space; to determine the EM field contribution of the display to each of the plurality of display elements by calculating the electromagnetic (EM) field propagation from the primitive to the display element in a three-dimensional coordinate system for each of the plurality of primitives; to generate the sum of the EM field contributions from the plurality of primitives to the display element for each of the plurality of display elements; and to transmit a respective control signal for each of the plurality of display elements based on the sum of the EM field contributions to the display element for modulation of at least one characteristic of the display element.

In some implementations, the optical device may include any one of the optical devices comprising at least one color-selective polarizer as described herein.

In some implementations, the optical device includes one of the optical devices comprising at least one reflective layer as described herein.

In some implementations, the optical device includes a holographic grid formed on a recording medium.

In some implementations, the optical device includes a plurality of holographic gratings formed on a recording medium, each of which is configured to diffract light of a particular color with a particular angle of incidence toward a display.

In some implementations, the optical device is positioned in front of the display, and the display is configured to diffract light through the optical device to form a three-dimensional light field corresponding to the object.

In some implementations, the system further includes an irradiator positioned adjacent to the optical device and configured to supply light to the optical device.

In some implementations, the controller is configured to sequentially modulate the display with information associated with multiple colors corresponding to multiple colors of light over a series of periods, and to control the irradiator to sequentially emit each of the multiple colors of light into the optical device during each period of the series, such that each of the multiple colors of light is diffracted by the optical device toward the display and reflected by the modulated display elements of the display, forming a three-dimensional light field of each color corresponding to an object within each period.

Another aspect of this disclosure features a method for fabricating any one of the optical devices described herein.

Another aspect of this disclosure features a method for fabricating any one optical device including at least one color-selective polarizer, comprising: forming a first optical diffraction component; forming a second optical diffraction component; and arranging a color-selective polarizer between the first and second optical diffraction components.

In some implementations, forming the first optical diffraction component includes forming the first diffraction structure on the recording medium.

In some implementations, forming a first diffraction structure on a recording medium involves recording a first holographic grating on the recording medium by irradiating it with a first recording object beam at a first recording object angle and a first recording reference beam at a first recording reference angle, wherein the first recording object beam and the first recording reference beam have the same wavelength and the same first polarization state.

In some examples, the light of the first color is broader than or contains the same wavelength range as the first recording reference beam or the first recording object beam. In some examples, the first recording reference beam corresponds to a color different from the first color of the light of the first color.

In some examples, the first incident angle of light of the first color is substantially identical to the first recording reference angle, and the first diffraction angle is substantially identical to the first recording object angle.

In some examples, the first recording reference angle is in the range of 70 to 90 degrees. In some examples, the first recording reference angle is in the range of 80 to 90 degrees. In some examples, the angle of the first recording object is in the range of -10 to 10 degrees. In some examples, the angle of the first recording object is substantially identical to 6 degrees. In some examples, the angle of the first recording object is substantially identical to 0 degrees. In some examples, the sum of the first recording reference angle and the first recording object angle is substantially identical to 90 degrees.

In some implementations, the thickness of the recording medium is more than an order of magnitude greater than the wavelength of the first recording object beam. The thickness of the recording medium can be approximately 30 times greater than the wavelength of the first recording object beam.

In some implementations, forming a first diffraction structure on a recording medium includes fixing the first diffraction structure to the recording medium.

In some implementations, the recording medium is located between the carrier film and the diffraction substrate.

In some embodiments, the first diffraction angle and the second diffraction angle are substantially identical to each other. In some examples, the first incident angle and the second incident angle are substantially identical to each other.

In some implementations, arranging a color-selective polarizer between a first optical diffraction component and a second optical diffraction component involves sequentially stacking the first optical diffraction component, the color-selective polarizer, and the second optical diffraction component such that light of the first color and light of the second color are incident on the first optical diffraction component before the second optical diffraction component.

In some implementations, sequentially stacking a first optical diffraction component, a color-selective polarizer, and a second optical diffraction component includes sequentially arranging the first optical diffraction component, the color-selective polarizer, and the second optical diffraction component on a substrate prior to the first optical diffraction component.

In some implementations, sequentially stacking a first optical diffraction component, a color-selective polarizer, and a second optical diffraction component includes attaching the color-selective polarizer to the first optical diffraction component via a first intermediate layer, and attaching the second optical diffraction component to the color-selective polarizer via a second intermediate layer, wherein each of the first and second intermediate layers includes a refractive index matching material.

In some implementations, the method further includes: forming a third optical diffraction component configured to diffract light of a third color having a first polarization state and a third incident angle at a third diffraction angle with a third diffraction efficiency; and arranging a second color-selective polarizer between the second and third optical diffraction components, wherein the second color-selective polarizer is configured to rotate the polarization state of the light of the third color from a second polarization state to a first polarization state.

In some implementations, a color-selective polarizer is configured to rotate the polarization state of light of a first color from a first polarization state to a second polarization state, while a second color-selective polarizer is configured to rotate the polarization state of light of a second color from a first polarization state to a second polarization state without rotating the polarization state of light of the first color.

In some implementations, the method further includes arranging a third color-selective polarizer in conjunction with a third optical diffraction component, such that the third optical diffraction component is located between a second color-selective polarizer and a third color-selective polarizer, wherein the third color-selective polarizer is configured to rotate the polarization states of the first and second colored light, respectively, from a second polarization state to a first polarization state, without rotating the polarization state of the third color of light.

In some implementations, the method further includes arranging a fourth color-selective polarizer in front of a first optical diffraction component, such that the first optical diffraction component is between the fourth color-selective polarizer and the fourth color-selective polarizer, wherein the fourth color-selective polarizer is configured to rotate the polarization state of the first color light from the second polarization state to the first polarization state without rotating the polarization states of the second and third color light, respectively.

In some implementations, the first polarization state is s-polarization, and the second polarization state is p-polarization.

Another aspect of the present disclosure is a method for fabricating any one optical device comprising at least one reflective layer, comprising: forming a first optical diffraction component comprising a first diffraction structure; forming a second optical diffraction component comprising a second diffraction structure; and arranging a first reflective layer between the first and second diffraction structures, wherein the second diffraction structure is continuous with the first diffraction structure along a certain direction; and arranging a second reflective layer continuous with the second diffraction structure along a certain direction.

In some implementations, the method further includes forming a light absorber on the side surface of an optical device, wherein the light absorber is configured to absorb fully reflected light of a first color and a second color.

In some implementations, the first reflective layer is configured to have a lower refractive index than the layer of the first optical diffraction component directly adjacent to the first reflective layer. Therefore, light of a first color with a first incident angle is completely reflected by the interface between the first reflective layer and the layer of the first optical diffraction component without completely reflecting light of a second color with a second incident angle.

In some implementations, the method further includes forming a third optical diffraction component, which includes a third diffraction structure configured to diffract light of a third color having a third angle of incidence, and arranging a second reflective layer continuously with the second diffraction structure along the direction includes arranging a second reflective layer between the second diffraction structure and the third diffraction structure along the direction. Each of the first and second reflective layers may be configured to transmit light of a third color having a third angle of incidence.

In some implementations, the method further includes arranging a third reflective layer in a direction continuous with the third diffraction structure, wherein the third reflective layer is configured to completely reflect light of a third color having a third angle of incidence.

In some implementations, each of the first, second, and third optical diffraction components includes a carrier film and a diffraction substrate, and the first reflective layer includes the first carrier film of the first optical diffraction component. Placing the first reflective layer between the first and second diffraction structures may include attaching the second diffraction substrate of the second optical diffraction component to the first carrier film of the first optical diffraction component by a first intermediate layer. Placing the second reflective layer between the second and third diffraction structures along a certain direction may include attaching the second carrier film of the second optical diffraction component to the third carrier film of the third optical diffraction component by a second intermediate layer. The second reflective layer may include a second intermediate layer. The third reflective layer may be attached to the third diffraction substrate of the third optical diffraction component.

In some implementations, the method further includes arranging the first optical diffraction component on a substrate in front of the first optical diffraction component along a direction, wherein the substrate includes a front and a back surface.

In some implementations, arranging the first optical diffraction component on the substrate includes attaching the front surface of the first optical diffraction component to the back surface of the substrate via a refractive index matching material.

In some implementations, the substrate includes sides angled relative to the back surface, and the substrate is configured to receive light of multiple different colors on these sides. The substrate can be configured so that light of multiple different colors is incident on the sides at an incident angle substantially identical to 0 degrees.

In some implementations, forming a first optical diffraction component including a first diffraction structure includes forming a first diffraction structure on a recording medium.

In some implementations, forming a first diffraction structure on a recording medium involves recording a first holographic grating on the recording medium by injecting a first recording object beam at a first recording object angle and a first recording reference beam at a first recording reference angle, wherein the first recording object beam and the first recording reference beam have the same wavelength and the same polarization state.

In some implementations, the light of the first color includes a wavelength range that is broader than or the same as the first recording reference beam.

In some implementations, the first recording reference beam corresponds to a color different from the first color of the first color of light.

In some implementations, the first incident angle of light of the first color is substantially the same as the first recording reference angle, and the first diffraction angle is substantially the same as the angle of the first recording object.

In some examples, the first recording reference angle is in the range of 70 to 90 degrees. In some examples, the first recording reference angle is in the range of 70 to 80 degrees. In some examples, the angle of the first recording object is in the range of -10 to 10 degrees.

In some implementations, the thickness of the recording medium is more than an order of magnitude greater than the wavelength of the first recording object beam. The thickness of the recording medium can be approximately 30 times greater than the wavelength of the first recording object beam.

In some implementations, forming a first diffraction structure on a recording medium includes fixing the first diffraction structure to the recording medium.

In some implementations, the first incident angle is different from the second incident angle. In some examples, the light of the first color has a smaller (or shorter) wavelength than the light of the second color, and the first incident angle is larger (or longer) than the second incident angle.

Another aspect of this disclosure features a method comprising forming one of the optical devices described herein by any one of the methods described above, and arranging the optical device and a display including a plurality of display elements such that the optical device is configured to diffract light of a plurality of different colors toward the display.

In some implementations, arranging the optical device and display involves separating the back of the optical device from the front of the display by a gap.

In some implementations, the method further includes forming an anti-reflective coating on at least one of the front surface of the display or the back surface of the optical device.

In some implementations, arranging the optical device and the display involves mounting the back of the optical device onto the front of the display via an intermediate layer.

In some cases, the intermediate layer is configured to have a refractive index lower than that of the optical device layer, such that each of the multiple different colors of light transmitted by the optical device in zero order is completely reflected at the interface between the intermediate layer and the optical device layer.

In some implementations, optical devices are configured to diffract light of multiple different colors at diffraction angles that are substantially identical to each other.

In some examples, each diffraction angle falls within the range of -10 degrees to 10 degrees.

In some implementations, the display is configured to diffract the diffracted color light backward through an optical device.

In some implementations, a portion of the optical device covers a portion of the display.

In some implementations, the optical device includes a substrate in front of it and is configured to receive light of multiple different colors on the side of the substrate that is angled relative to the back surface of the substrate.

Another aspect of this disclosure features a method comprising using an optical device to convert an incident beam containing light of several different colors into light of individually diffracted colors. The optical device may be any one of the optical devices described herein.

Another aspect of this disclosure features a method comprising: transmitting at least one timing control signal to an irradiator to activate the irradiator and emit light of multiple different colors into the optical device, wherein the optical device is any one of the optical devices described herein; and transmitting at least one respective control signal to each of the multiple display elements of the display to modulate the display elements, such that the individually diffracted light of each color is reflected by the modulated display elements to form a multicolor three-dimensional light field corresponding to each control signal.

In some implementations, the method further includes: obtaining graphic data containing primitive data for multiple primitives corresponding to an object in three-dimensional space; determining the EM field contribution to each of the multiple display elements of a display by calculating the electromagnetic (EM) field propagation from the primitive to the display element in a three-dimensional coordinate system for each of the multiple primitives; generating the sum of the EM field contributions from the multiple primitives to the display element for each of the multiple display elements; and generating a control signal for each of the multiple display elements based on the sum of the EM field contributions to the display element for modulation of at least one characteristic of the display element, wherein the multicolor three-dimensional light field corresponds to the object.

In some implementations, the method includes sequentially modulating a display with information associated with multiple different colors over a series of periods, and controlling an irradiator to sequentially emit each of the multiple colors of light into the optical device within each period of the series, such that each of the multiple colors of light is diffracted by the optical device toward the display and reflected by the modulated display elements of the display, forming a corresponding three-dimensional light field of each color for an object within each period.

In some implementations, multiple different colored lights are diffracted by the optical device at substantially the same diffraction angle relative to the display. In some examples, the diffraction angle is in the range of -10 to 10 degrees.

In some implementations, the irradiator and optical device are configured such that multiple different colored lights are incident on a first optical diffraction component of the optical device at their respective incident angles. In some examples, the incident angles are different from each other. In some examples, the incident angles are substantially the same from each other. In some examples, each of the incident angles is in the range of 70 to 90 degrees.

Another aspect of this disclosure features an optical device comprising at least two optical diffraction components and at least one color-selective polarizer, wherein the optical device is configured to separate individual lights of different colors while suppressing crosstalk between the different colors when light of different colors is incident upon it.

In some implementations, when light of different colors is incident on the optical device, each of the optical diffraction components is configured to diffract light of each of the different colors.

In some implementations, the optical device is configured such that, in the output light beam diffracted by the optical device, the power of a particular color of light among the different colors is at least an order of magnitude higher than the power of one or more other colors of light among the different colors.

In some implementations, at least one color-selective polarizer is configured to rotate the polarization state of at least one of the different colors of light, such that light of a specific color among the different colors is incident on each of the optical diffraction components in a first polarization state, while light of one or more other colors among the different colors is incident on each of the optical diffraction components in a second polarization state different from the first polarization state.

Another aspect of this disclosure features an optical device comprising at least two optical diffraction components and at least one reflective layer, wherein the optical device is configured to separate individual lights of different colors while suppressing crosstalk between the different colors when light of different colors is incident upon it, and the at least one reflective layer is configured for total internal reflection of at least one of the different colors of light.

In some implementations, the optical device is configured such that the output light beam diffracted by the optical device contains only light of a specific color from among the different colors, without crosstalk from one or more other colors.

In some implementations, at least one reflective layer is configured to completely reflect zero-order light of a specific color among the different colors transmitted by each of the optical diffraction components, while transmitting one or more other colors among the different colors.

In some implementations, when light of different colors is incident on the optical device, each of the optical diffraction components is configured to diffract light of each of the different colors.

Another aspect of this disclosure features either a display or one of the optical devices described herein, the optical device being configured to diffract light of multiple different colors toward the display.

Another aspect of this disclosure features an irradiator configured to provide light of multiple different colors, and one of the optical devices described herein, the optical device configured to diffract the light of multiple different colors from the irradiator.

Another aspect of this disclosure features a system comprising a display and an optical device including one or more transmission diffraction structures for diffracting light toward the display.

In some implementations, the display is a reflective display configured to diffract light through an optical device. In some implementations, the system further includes an irradiator configured to supply light to the optical device, the irradiator being positioned in front of the transmission diffraction structure of the optical device.

In some implementations, the display is a transmissive display configured to diffract light forward through an optical device. In some implementations, the system further includes an irradiator configured to supply light to the optical device, the irradiator being located behind the transmissive diffraction structure of the optical device.

In some implementations, each of the one or more transmission diffraction structures is configured to diffract each of several different colors.

In some implementations, the optical device further includes one or more reflection diffraction structures, and each of the one or more transmission diffraction structures and the one or more reflection diffraction structures is configured to diffract each of a plurality of different colors.

Another aspect of this disclosure features a system comprising a display and an optical device including one or more reflection-diffraction structures for diffracting light toward the display.

In some implementations, the display is a reflective display configured to diffract light through an optical device. In some implementations, the system further includes an irradiator configured to supply light to the optical device, the irradiator being located behind the reflective diffraction structure of the optical device.

In some implementations, the display is a transmissive display configured to diffract light forward through an optical device. In some implementations, the system further includes an irradiator configured to supply light to the optical device, the irradiator being positioned in front of the reflective diffraction structure of the optical device.

In some implementations, each of the one or more reflection diffraction structures is configured to diffract each of several different colors.

In some implementations, the optical device further includes one or more transmission diffraction structures, and each of the one or more transmission diffraction structures and one or more reflection diffraction structures is configured to diffract each of a plurality of different colors.

Another aspect of this disclosure features an optical device comprising a plurality of optical diffraction components, each comprising at least one transmission diffraction structure and at least one reflection diffraction structure, wherein the optical device is configured to separate individual lights of different colors while suppressing crosstalk between the different colors when light of different colors is incident upon it.

In some implementations, the transmission diffraction structure and the reflection diffraction structure are configured to diffract light of different colors.

In some implementations, the optical device further includes at least one reflective layer configured for total internal reflection of at least one light of a different color.

In some implementations, the optical device further includes at least one color-selective polarizer configured to rotate the polarization state of at least one of the different colors of light, such that light of a specific color among the different colors is incident on each of the optical diffraction components in a first polarization state, while light of one or more other colors among the different colors is incident on each of the optical diffraction components in a second polarization state different from the first polarization state.

Another aspect of this disclosure features a system comprising a display and an optical device comprising one of the optical devices described herein, wherein the optical device is configured to diffract light of multiple different colors toward the display.

Another aspect of this disclosure features a system comprising an irradiator configured to provide light of multiple different colors, and an optical device comprising one of the optical devices described herein, wherein the optical device is configured to diffract light of multiple different colors from the irradiator.

In this disclosure, the term “primitive” refers to a fundamental, indivisible element for input or output within a computing system. The element may be a geometric or graphical element. The term “hologram” refers to a pattern displayed by (or uploaded to) a display, including amplitude information, phase information, or any combination thereof, relating to an object. The term “holographic reconstruction” refers to the volume light field (e.g., holographic light field) from a display when illuminated.

Details of one or more implementations of the subject matter described herein are given in the accompanying drawings and related descriptions. Other features, embodiments, and advantages of the subject matter will become apparent from the specification, drawings, and claims.

It should be understood that various implementation configurations can be combined in different ways. For example, features from a particular method, device, or system can be combined with features from other methods, devices, or systems.

A schematic diagram illustrating an exemplary system including a holographic display is provided. A schematic diagram of an exemplary holographic display is provided as an example. This document illustrates an exemplary system for 3D displays. This document illustrates an exemplary configuration for electromagnetic (EM) propagation calculations. This illustrates exemplary EM propagation of point primitives to display elements. This example illustrates the exemplary EM propagation of line primitives to display elements. This example illustrates the exemplary EM propagation of triangular primitives to display elements. This document illustrates an exemplary implementation of Maxwell holographic occlusion for a point primitive having a line primitive as an occluder. This illustrates an exemplary implementation of Maxwell holographic occlusion for a line primitive that has another line primitive acting as an occluder. This document illustrates an exemplary implementation of Maxwell holographic occlusion for a triangle primitive with a line primitive as an occluder. This document illustrates an exemplary implementation of Maxwell holographic stitching. This is an illustrative flowchart of the process for displaying objects in 3D. An exemplary system for a 3D display, including a reflective display with front illumination, is illustrated. Another exemplary system for a 3D display, including a reflective display with full-surface illumination, is illustrated. Another exemplary system for a 3D display, including a transmissive display with back illumination, is illustrated. Another exemplary system for a 3D display, including a transmissive display with waveguide irradiation, is illustrated. Another exemplary system for a 3D display, including a transmissive display with waveguide irradiation, is illustrated. Another exemplary system for a 3D display, including a reflective display with waveguide irradiation, is illustrated. Another exemplary system for a 3D display, including a reflective display with waveguide irradiation, is illustrated. Another exemplary system for a 3D display is illustrated, including a reflective display with optical diffraction irradiation using a transmission field lattice-based structure. Another exemplary system for a 3D display is illustrated, including a reflective display with optical diffraction irradiation using a reflection field grid-based structure. Another exemplary system for a 3D display is illustrated, including a transmissive display with optical diffraction irradiation using a reflection field grid-based structure. Another exemplary system for a 3D display is illustrated, including a transmission display with optical diffraction irradiation using a transmission field lattice-based structure. An example display having display elements with non-uniform shapes will be illustrated. An exemplary display with display elements of different sizes is illustrated. This example illustrates how to record a grid onto a recording medium. An example of diffracting a regenerated reference beam using the grating shown in Figure 7A is illustrated below. This example illustrates how to record grids of different colors onto a recording medium using light of different colors. This example illustrates how to record grids of different colors onto a recording medium using light of the same color. This example illustrates how different colored gratings can be used to diffract regenerated reference beams of different colors. This example illustrates crosstalk between diffracted beams of different colors.

This example illustrates how to record a diffraction grating with a large reference angle onto a recording medium. An exemplary optical device is illustrated that includes two-color diffraction gratings and corresponding color-selective polarizers for diffracting two colors of light separately. An example of how the optical device shown in Figure 9A diffracts two colors of light is illustrated. An exemplary optical device is illustrated that includes three color diffraction gratings and corresponding color-selective polarizers for diffracting three colors of light individually. An example of how the optical device shown in Figure 10A diffracts three colors of light is illustrated. An exemplary optical device is illustrated that includes two-color diffraction gratings and corresponding reflective layers for diffracting two colors of light separately. An exemplary optical device is illustrated that includes three-color diffraction gratings and corresponding reflective layers for individually diffracting three colors of light. Another exemplary optical device is illustrated, which includes a diffraction grating of three colors and a corresponding reflective layer having a wedge-shaped substrate. Further exemplary optical devices are illustrated, including diffraction gratings of three colors and corresponding reflective layers having wedge-shaped input surfaces. The relationship between diffracted beam power and reflected beam power with different incident angles for blue light (Figure 13A), green light (Figure 13B), and red light (Figure 13C) will be illustrated with examples. The relationship between diffracted beam power and reflected beam power with different incident angles for blue light (Figure 13A), green light (Figure 13B), and red light (Figure 13C) will be illustrated with examples. The relationship between diffracted beam power and reflected beam power with different incident angles for blue light (Figure 13A), green light (Figure 13B), and red light (Figure 13C) will be illustrated with examples. This is a flowchart illustrating an exemplary process for manufacturing an optical device including a holographic grating and a corresponding color-selective polarizer. This is a flowchart illustrating an exemplary process for manufacturing an optical device including a holographic grating and a corresponding reflective layer. An exemplary optical device, including a combination of a transmission diffraction grating and a reflection diffraction grating, is illustrated. An example of incident light that is diffracted by the display elements of a display and reflected by the gaps between the display elements on the display will be illustrated. This section illustrates an example of zero-order optics in a holographic scene displayed on a projection screen. This example illustrates the zero-order luminescence of a display within a holographic scene seen by the viewer. This paper illustrates an example of suppressing zero-order light in a holographic scene displayed on a projection screen by diverging the zero-order light of the display. This example illustrates the zero-order illuminance of a display in a holographic scene when the display is illuminated with light incident perpendicularly. This example illustrates how, when a display is illuminated with light at a certain angle of incidence, the zeroth-order light from the display can be directed away from the holographic scene, thereby suppressing the zeroth-order light from the display in the holographic scene displayed on the projection screen. This example illustrates how, when a display is illuminated with light at a certain angle of incidence, the zeroth-order light of the display can be directed away from the holographic scene, thereby suppressing the zeroth-order light of the display in the holographic scene displayed to the viewer's eye. An example of a constructing cone and a reconstructing cone corresponding to a holographic scene on a display in a 3D coordinate system is illustrated. An example of adjusting the cone configuration in Figure 20A to construct a hologram corresponding to a holographic scene in a 3D coordinate system is illustrated. This example illustrates how to couple light to an optical diffraction device via a coupling prism to illuminate a display at an incident angle that suppresses zero-order light in a holographic scene. This example illustrates how light is coupled to an optical diffraction device via a wedge-shaped substrate to illuminate a display at an incident angle that suppresses zero-order light in a holographic scene. This example illustrates how to suppress display-zero-order light in a holographic scene displayed on a projection screen by absorbing the display-zero-order light reflected from the display using a metamaterial layer. This example illustrates how a metamaterial layer can block (or absorb) the zero-order display light reflected from the display, thereby suppressing the zero-order display light in the holographic scene displayed to the viewer's eye. This example illustrates a system that suppresses display zero-order light in a holographic scene by redirecting it away from the holographic scene via an optical redirection structure. This example illustrates how to redirect zero-order display light in different directions within space via an optical redirection structure. This example illustrates how to redirect zero-order display light in different directions within space via an optical redirection structure. This example illustrates how to redirect zero-order display light in different directions within space via an optical redirection structure. This example illustrates how zero-order light in a display can be redirected when light is input in different directions in space via an optical redirection structure at different angles of incidence. This example illustrates how zero-order light in a display can be redirected when light is input in different directions in space via an optical redirection structure at different angles of incidence. This example illustrates how zero-order light in a display can be redirected when light is input in different directions in space via an optical redirection structure at different angles of incidence. This example illustrates how zero-order light in a display can be redirected when light is input in different directions in space via an optical redirection structure at different angles of incidence. This example illustrates how zero-order light in a display can be redirected when light is input in different directions in space via an optical redirection structure at different angles of incidence. This example illustrates how to redirect p-polarized zero-order light from a display to transmit it at the Blue Star angle. This example illustrates how to redirect s-polarized zero-order display light using an optical retarder for transmission at the Blue Star angle. This example illustrates how to redirect s-polarized zero-order display light using an optical retarder for transmission at the Blue Star angle. This example illustrates how to redirect the zero-order light from a display to an anisotropic transmitter in order to absorb the zero-order light from the display. This example illustrates how to redirect the zero-order light from a display so that it is completely reflected. This example illustrates redirecting zero-order light from two different colored displays in different directions away from the holographic scene. This example illustrates redirecting zero-order light from two different colored displays in different directions away from the holographic scene. This example illustrates redirecting three different colored zero-order display luminescences in different directions away from the holographic scene, all within the same plane. This example illustrates redirecting three different colored zero-order display luminescences in different directions away from the holographic scene, all within the same plane. This example illustrates redirecting three different colored zero-order display luminescences in different directions away from a holographic scene in space. This example illustrates how to redirect three different colored zero-order display luminescences in different directions away from a holographic scene, using a switchable grid for one of the colors. This is a flowchart illustrating an exemplary process for suppressing zero-order illuminance in a holographic scene. This example illustrates a system for displaying reconstructed 3D objects. This example illustrates a system for displaying reconstructed 3D objects. This example illustrates a system for displaying reconstructed 3D objects. Figures 36A to 36C illustrate the propagation of three colors of light within the system, using the same diagrams as those in Figures 35A to 35C. Figures 36A to 36C illustrate the propagation of three colors of light within the system, using the same diagrams as those in Figures 35A to 35C. Figures 36A to 36C illustrate the propagation of three colors of light within the system, using the same diagrams as those in Figures 35A to 35C.

Similar reference numbers and names in various drawings illustrate similar elements.

The implementation aspects of this disclosure feature a technique for enabling 3D display of complex computer-generated scenes as true holograms. The technique provides a novel and deterministic solution to real-time dynamic computational holography based on Maxwell's equations for electromagnetic fields, which can be represented as Maxwell holography. The computation (or calculation) in Maxwell holography can be represented as Maxwell holographic computation (or Maxwell holographic computation). In embodiments, the disclosure utilizes tools including field theory, topology, analytical continuation, and/or symmetry groups to approach the hologram as a Dirichlet or Cauchy boundary condition problem for a general electric field, which enables solving for the hologram in real time without the limitations of conventional holographic systems. In embodiments, this technique can be used to produce phase-only, amplitude-only, or phase and amplitude holograms using a spatial light modulator (SLM) or any other holographic device.

The implementations of this disclosure can provide: 1) a mechanism for approximating holograms as electromagnetic boundary conditions using field theory and contact geometry instead of classical optical systems; 2) derivation and implementation of the electromagnetic boundary condition approach to computational holography into computer code and application programming interfaces (APIs), i.e., implementations of hologram computation as a 2D analysis function on the plane of the hologram and subsequent discretization into parallel algorithms; and/or 3) implementations of full 3D holographic versions of standard computer graphics primitives (e.g., points, lines, triangles, and textured triangles) that enable full compatibility with standard existing computer graphics tools and techniques. These techniques enable devices to display common existing content that has not been specifically created for holography, and at the same time, enable existing content creators to create holographic works without needing to learn special techniques or use special tools.

In particular, the techniques disclosed herein may involve the use of a mathematical formulation (or representation) of light as an electromagnetic (EM) phenomenon, instead of the mathematical formulation of classical optical systems commonly used in computational holography, such as the Gerchberg-Saxton (G-S) algorithm. The mathematical formulation disclosed herein is derived from Maxwell's equations. In embodiments, the techniques disclosed herein include treating a displayed image as an electromagnetic field and treating a hologram as boundary value conditions (e.g., the Dirichlet problem) that generate an electromagnetic field. In addition, the desired image can be constructed using a primitive paradigm ubiquitous in computer graphics, enabling, for example, a technique used to display an arbitrary 3D image not as a projected image on a 2D screen, but as a holographic reconstruction, e.g., a holographic light field. Compared to depth point cloud techniques that suffer from bandwidth limitations, the techniques circumvent these limitations and can use any suitable type of primitive, such as point primitives, line primitives, or polygonal primitives such as triangle primitives. Furthermore, primitives can be rendered with color information, texture information, and/or shading information. This can help achieve recording and compression schemes for CG holographic content, including holographic video.

In embodiments, the techniques disclosed herein use Maxwell's equations to compute a generated hologram as a boundary condition problem for modeling an electromagnetic field, thereby eliminating dependence on the Fast Fourier Transform (FFT) and its inherent limitations, eliminating dependence on collimated light sources such as lasers or light-emitting diodes (LEDs), and/or eliminating the limitations of previous approaches to computational holography and non-deterministic solutions.

In embodiments, the techniques disclosed herein can be optimized for computational simplicity and speed through a mathematical optimization process that constrains independent inputs on the surface of the hologram, depending on the parameters of the computer-generated (CG) primitives required to construct the scene. This enables highly parallel and highly optimized operation in computing architectures, such as application-specific integrated circuits (ASICs) and multi-core architectures. The process of computing the hologram can be viewed as a single instruction executed on input data in the form of a computer-generated image (CGI) scene, and theoretically, can be completed in a single clock cycle per CGI primitive.

In embodiments, the techniques disclosed herein treat holographic scenes as assemblies of fully 3D holographic primitive apertures functionally compatible with conventional 3D graphics standard primitives used, for example, in video games, movies, television, computer displays, or any other display technology. These techniques can enable efficient implementations of these aperture primitives in hardware and software without the limitations inherent in standard implementations of computational holography. The amplitude and color of the primitives can be automatically calculated. The computational complexity can increase linearly with the number of phase elements n, compared to n^2 or n*log(n) in standard computational holography. The resulting image is fully 3D and not a collection of planar images, and the technique does not require repeated amplitude correction with an unknown number of steps. Furthermore, the generated hologram does not have “conjugate” images occupying space on the holographic device.

Because holographic primitives are part of a special collection of mathematical objects, they can be computed relatively simply and relatively quickly, making them uniquely suited to parallel distributed computing approaches. Computability and parallelism enable the interactive computation of large holograms, allowing for the design of theoretically unlimited-size, large-area holographic devices that can function as holographic computer displays, telephone displays, home theaters, and even holographic rooms. Furthermore, holograms can fill large areas with light, rendering large shaded areas in 3D without the limitations associated with conventional holographic computation methods, such as elements appearing as contours instead of solids. Moreover, the relatively simple and relatively fast computation allows for real-time display of holograms at interactive speeds unconstrained by n^2 computation load and iterative amplitude correction.

In embodiments, the technology can achieve natural computability on modern ASIC and multicore architectures and achieve full compatibility with modern graphics hardware, modern graphics software, and/or modern graphics tools and toolchains. For example, these technologies can implement a clear and easy-to-use holographic API, which can enable high-performance rendering of any CG model using conventional 3D content creation tools, such as 3ds Max®, SOLIDWORKS®, Maya®, or Unity. The API can enable developers or users to interact with holographic devices, such as optical modulators or holographic systems. The holographic API can create computer graphics primitives as individual holographic scene primitives, enabling the generation of rich holographic content using general-purpose and specially designed holographic computation hardware. The creation of mathematical and computational architectures can enable holograms to be rendered using tools and technologies used to create conventional 3D content and software applications. Optimization of the mathematical and computational architectures can enable high-performance embodiments of conventional graphics and rendering to be displayed as holographic reconstructions.

The algorithms in the techniques disclosed herein are relatively easy to implement in hardware. This not only enables the computational speed necessary for the high-quality rendering expected by users, but also allows the algorithms to be implemented in relatively simple circuits, such as ASIC gate structures, as part of a holographic device. Therefore, bandwidth issues that can plague high-density displays may become irrelevant, as scene computation can be spread across the computing architecture embedded in the display device (e.g., embedded computation), without the need to be computed remotely and then written to each display element (or display pixel) of the display for each frame of content. Furthermore, the number of display elements, and therefore the size of the holographic display, are not significantly limited by the constraints that severely restrict other techniques.

The technologies disclosed herein enable the relatively simple and inexpensive implementation of multiple interactive technologies using structured light in a variety of applications, including, for example, solid-state light detection and ranging (LIDAR) devices, 3D printing and machining, smart illuminators, smart microdisplays, optical switching, optical tweezers, or any other applications requiring structured light. The technologies disclosed herein can also be used in optical simulations, such as lattice simulations.

Figure 1A illustrates a schematic diagram of an exemplary system 100 for a 3D display. System 100 includes a computing device 102 and a holographic display device (or Maxwell holographic display device) 110. The computing device 102 is configured to prepare data for a list of primitives corresponding to objects, e.g., 3D objects, and to transmit the data to the holographic display device 110 via a wired or wireless connection, e.g., a USB-C connection or any other high-speed serial connection. The holographic display device 110 is configured to calculate electromagnetic (EM) field contributions from the list of primitives and display elements of a display (e.g., a modulator) within the holographic display device 110; to modulate the display elements with a pattern, e.g., a hologram, based on the calculated EM field contributions on the display; and, upon illumination, to display a light field corresponding to the object in 3D, e.g., a holographic reconstruction. In this specification, a hologram refers to a pattern displayed on the display that includes amplitude information, or any combination thereof, relating to an object. Holographic reconstruction refers to the volume light field (e.g., holographic light field) from a display when illuminated.

The computing device 102 may be any suitable type of device, such as a desktop computer, personal computer, notebook, tablet computing device, personal digital assistant (PDA), network appliance, smart mobile phone, smartwatch, High-Speed General-Purpose Packet Radio Service (EGPRS) mobile phone, media player, navigation device, email device, game console, or any two or more suitable combinations of these computing devices or other computing devices.

The computing device 102 includes an operating system (OS) 104 that can include several applications 106 as graphics engines. The applications 106 can process or render scenes, such as any arbitrary CG model, using standard 3D content creation tools, such as 3ds Max®, SOLIDWORKS®, Maya®, or Unity. A scene can correspond to one or more real or imaginary 3D objects, or representations of objects. The applications 106 can operate in parallel to render the scene and obtain an OS graphics abstraction 101 that can be provided to a graphics processing unit (GPU) 108 for further processing. In some implementations, the OS graphics abstraction 101 is provided to a holographic display device 110 for further processing.

The GPU 108 may include special electronic circuits designed for rapid operation of computer graphics and image processing. The GPU 108 can process a graphics abstraction 101 of the scene to obtain processed scene data 103, which can be used, for example, to obtain a list 105 of primitives indexed in a specific order. The primitives may include at least one of point primitives, line primitives, or polygon primitives. In some implementations, the GPU 108 includes a video driver configured to generate the processed scene data 103 and the list 105 of primitives.

In some implementations, the GPU 108 includes a conventional renderer 120, which allows the list of primitives 105 to be rendered into a list of items to be drawn on a conventional monitor 124, for example, a 2D display screen, using conventional rendering techniques such as culling and clipping. The list of items can be transmitted to the conventional monitor 124 via a screen buffer 122.

In some implementations, the GPU 108 includes a holographic renderer 130 for rendering the list of primitives 105 into graphic data to be displayed by a holographic display device 110. The graphic data may include the list of primitives and corresponding primitive data. For example, the graphic data may include the hexadecimal code for each primitive.

In some implementations, the GPU 108 includes both a conventional renderer 120 and a holographic renderer 130. In some implementations, the GPU 108 includes a conventional renderer 120, and the holographic display device 110 includes a holographic renderer 130.

The corresponding primitive data for a primitive may also include color information (e.g., texture color, gradient color, or both), texture information, and/or shading information. Shading information can be obtained by any conventional CGI surface shading method, which involves modulating the color or brightness of the primitive's surface.

The primitive data of a primitive can include coordinate information of the primitive in a 3D coordinate system, such as the Cartesian coordinate system (XYZ), polar coordinate system, cylindrical coordinate system, and spherical coordinate system. As will be discussed in more detail below, the display elements within the holographic display device 110 can also have corresponding coordinate information in a 3D coordinate system. The primitive of a coordinate location can represent a 3D object adjacent to the display element, for example, in front of the display element, behind the display element, or spanning the display element.

As an example, a primitive is a shaded line, for example, a straight line that smoothly changes from one color to another over its span. A primitive requires four elements of data to be rendered: two endpoints and color information (e.g., RGB color values) at each endpoint. Assuming the hexadecimal code of the line is a0 and the line extends from a first endpoint (0.1, 0.1, 0.1) to a second endpoint (0.2, 0.2, 0.2) in a 3D coordinate system, the color is 1/2 blue, RGB = (0, 0, 128) at the first endpoint, and the color is pure red, RGB = (255, 0, 0) at the second endpoint. The holographic renderer determines the amount and type of data to expect for each primitive. In the case of a line, the primitive data of a shaded line in the primitive stream can be a set of instructions such as the following:
0xa0 // Hex code for shaded line 0x3dcccccd // Float (single) first vertex (0.1, 0.1, 0.1)
0x3dccccccd
0x3dccccccd
0x000080 // The first vertex color is (0,0,128) 0x3e4ccccd // The second vertex (0.2,0.2,0.2) float (single)
0x3e4ccccd
0x3e4ccccd
0xff0000 // The color of the second vertex is (255, 0, 0)

The primitive data for the shaded line primitive contains a total of 31 hexadecimal words.
This can be a highly efficient method for transmitting complex scenes, and the primitive data can be further compressed. Since each primitive is a deterministic Turing step, no terminator is required. Unlike conventional models in which line primitives are simply drawn on a 2D display screen, the line primitive data is transmitted to a holographic display device 110 that can compute a hologram and display a corresponding holographic reconstruction that presents lines floating in space.

In some implementations, the computing device 102 transmits non-primitive-based data, such as recorded optical field video, to the holographic display device 110. The holographic display device 110 can calculate a sequence of holograms and display the video as a continuous holographic reconstruction in space. In some implementations, the computing device 102 transmits CG holographic content to the holographic display device 110 simultaneously with live holographic content. The holographic display device 110 can also calculate corresponding holograms and display the content as a corresponding holographic reconstruction.

As illustrated in Figure 1A, the holographic display device 110 includes a controller 112 and a display 114. The controller 112 may include several computing units or processing units. In some implementations, the controller 112 includes an ASIC, a field-programmable gate array (FPGA), or a GPU unit, or any combination thereof. In some implementations, the controller 112 includes a holographic renderer 130 for rendering a list of primitives 105 into graphic data computed by the computing units. In some implementations, the controller 112 receives an OS graphics abstraction 101 from the computing device 102 for further processing. The display 114 may include several display elements. In some implementations, the display 114 includes a spatial light modulator (SLM). The SLM may be a phase SLM, an amplitude SLM, or a phase and amplitude SLM. In some examples, the display 114 is a digital micromirror device (DMD) or a liquid crystal on silicon (LCOS) device. In some implementations, the holographic display device 110 includes an irradiator 116 adjacent to the display 114 and configured to emit light toward the display 114. The irradiator 116 may include one or more coherent light sources, e.g., lasers; one or more semi-coherent light sources, e.g., LEDs (light-emitting diodes) or super-light-emitting diodes (SLEDs); one or more non-coherent light sources; or a combination of such light sources.

Unlike conventional 3D graphics systems that capture a 3D scene and render it on a 2D display device, the holographic display device 110 is configured to generate 3D output, such as a holographic reconstruction 117, in the form of a light field, for example, the light of a 3D volume. In a hologram, each display element can contribute to any part of the holographic reconstruction of the scene. Therefore, for the holographic display device 110, each display element needs to be potentially modulated for every part of the scene, for example, each primitive in the list of primitives generated by the GPU 108, for a complete holographic reproduction of the scene. In some implementations, the modulation of certain elements can be omitted or simplified, for example, based on an acceptable level of accuracy within the reproduced scene or within certain areas of the scene.

In some implementations, the controller 112 is configured to calculate the EM field contribution from each primitive to each display element, e.g., phase, amplitude, or both, and to generate a sum of the EM field contributions to each display element from a list of primitives for each display element. This can be done by executing all primitives and increasing their contributions to a given display element, or by executing each display element for each primitive, or by a hybrid blend of these two techniques.

The controller 112 can calculate the EM field contribution from each primitive to each display element based on a predetermined equation for the primitive. Different primitives may have corresponding equations. In some cases, the predetermined equation is an analytical equation, as will be discussed in more detail below in relation to Figures 3A-3C. In some cases, the predetermined equation is determined by solving Maxwell's equations using boundary conditions defined in the display 114. The boundary conditions may include Dirichlet or Cauchy boundary conditions. The display elements can then be modulated based on the sum of the EM field contributions by modulating, for example, at least one of the following: refractive index, amplitude exponent, birefringence, or delay of the display element.

If the EM field at each point on the boundary surface, for example, the values of the solutions to Maxwell's equations, are known, the exact and unique configuration of the EM field within the volume bounded by the boundary surface can be determined. The list of primitives (or the corresponding holographic reconstruction of the hologram) and the display 114 define a 3D space, and the surface of the display 114 forms a portion of the boundary surface of the 3D space. The boundary conditions of the EM field can be determined by setting EM field states (e.g., phase states or amplitude states or phase and amplitude states) on the surface of the display 114, for example, by irradiating the display surface with light. Due to the time symmetry of Maxwell's equations, the display elements are modulated based on the EM field contributions from the primitives corresponding to the hologram, so that a volume light field corresponding to the hologram can be obtained as a hologram reconstruction.

For example, a line primitive illuminating in a specific color can be set in front of the display 114. As will be discussed in more detail below with respect to Figure 3B, the analytical formula for the linear aperture can be written as a function in space. Then, the EM field contribution from the line primitive on the interface containing the display 114 can be determined. If the EM field value corresponding to the calculated EM field contribution is set on the display 114, due to the time symmetry of Maxwell's equations, the same linear aperture used in the calculation can appear at the corresponding location, for example, at the coordinate position of the linear primitive in the 3D coordinate system, and in a specific color.

In some examples, we assume there is a line of light between two points A and B in 3D space, as will be discussed in more detail below with respect to Figure 3B. The light is uniformly illuminated and has an intensity I per line distance l. For every infinitesimal dl along the line from A to B, an amount of light proportional to I*dl is emitted. The infinitesimal dl acts as a delta (point) source, and the EM field contribution from the infinitesimal dl to any point on the interface around the scene corresponding to the list of primitives can be determined. Thus, for any display element of display 114, an analytical formula representing the EM field contribution at the display element from an infinitesimal segment of the line can be determined. A special addition/integral that progresses along the line and increases the EM field contribution of the entire line to the EM field at the display element of the display can be determined as a formula. The values corresponding to the formula can be set at the display element, for example, by modulating the display element and illuminating the display element. Then, by time reversal and correction constants, the line can be created at the same location defined by points A and B in 3D space.

In some implementations, the controller 112 is coupled to the display 114 via a memory buffer. The controller can generate control signals for each display element based on the sum of their EM field contributions. These control signals are used to modulate the display elements based on the sum of their EM field contributions. Each control signal is transmitted to the corresponding display element via the memory buffer.

In some implementations, the controller 112 is integrated with the display 114 and locally coupled to the display 114. As will be considered in more detail in relation to Figure 1B, the controller 112 may include several computing units, each coupled to one or more display elements and configured to transmit its respective control signals to each of the one or more display elements. Each computing unit may be configured to perform computations on one or more primitives in a list of primitives. The computing units can operate in parallel.

In some implementations, the irradiator 116 is coupled to a controller 112 and configured to be turned on/off based on a control signal from the controller 112. For example, the controller 112 can activate and turn on the irradiator 116 in response to the controller 112 completing a calculation, for example, obtaining the total of all EM field contributions for the display elements. As described above, when the irradiator 116 emits light onto the display 114, the modulated elements of the display propagate the light in different directions, forming a volume light field corresponding to a list of primitives corresponding to 3D objects. The resulting volume light field corresponds to a solution to Maxwell's equations with boundary conditions defined by the modulated elements of the display 114.

In some implementations, the controller 112 is coupled to the irradiator 116 via a memory buffer. The memory buffer can be configured to control the amplitude or brightness of the light-emitting elements within the irradiator. The memory buffer for the irradiator 116 may be smaller in size than the memory buffer for the display 114. Some of the light-emitting elements within the irradiator 116 may be smaller than some of the display elements of the display 114, as long as the light from the light-emitting elements can illuminate substantially the entire surface of the display 114. For example, an irradiator with 64 x 64 OLEDs (organic light-emitting diodes) can be used with a display having 1024 x 1024 elements. The controller 112 can be configured to operate several of the irradiating elements of the irradiator 116 simultaneously.

In some implementations, the irradiator 116 is a monochromatic light source configured to emit substantially monochromatic light, such as red, green, yellow, or blue light. In some implementations, the irradiator 116 includes two or more light-emitting elements, such as lasers or light-emitting diodes (LEDs), each configured to emit light of a different color. For example, the irradiator 116 may include red, green, and blue irradiating elements. To display a full-color 3D object, three or more separate holograms can be calculated for colors including at least red, green, and blue. That is, at least three EM field contributions can be obtained from the corresponding primitives to the display elements. The display elements can be sequentially modulated based on at least three EM field contributions, and the irradiator 116 can be controlled to sequentially turn on at least the red, green, and blue irradiating elements. For example, the controller 112 can transmit a first timing signal to turn on the blue irradiating element and transmit a first control signal corresponding to the blue hologram to display the elements of the display 114. After the blue hologram on the display 114 is illuminated with blue light for a first period, the controller 112 can transmit a second timing signal to turn on the green illumination element and transmit a second control signal corresponding to the green hologram to display the elements of the display 114. After the green hologram on the display 114 is illuminated with green light for a second period, the controller 112 can transmit a third timing signal to turn on the red illumination element and transmit a third control signal corresponding to the red hologram to display the elements of the display 114. After the red hologram on the display 114 is illuminated with red light for a third period, the controller 112 can repeat the above steps. Depending on the temporal coherence of the visual effect on the viewer's eye, the three colors can be combined in the eye to give a full-color appearance. In some cases, the illuminator 116 is turned off during a state change of the display image (or holographic reconstruction) and turned on when a valid image (or holographic reconstruction) is presented for a certain period of time. This can also rely on the temporal coherence of vision to ensure that the image (or holographic reconstruction) appears stable.

In some implementations, the display 114 has a resolution small enough to diffract visible light to an order of, for example, 0.5 μm or less. The irradiator 116 may include a single white light source, and the emitted white light can be diffracted to different colors by the display 114 for holographic reconstruction.

As will be discussed in more detail below with respect to Figures 5A-5K, different configurations for System 100 are possible. The display 114 may be reflective or transmissive. The display 114 can have various sizes ranging from small (e.g., 1-10 cm on each side) to large (e.g., 100-1000 cm on each side). Illumination from the irradiator 116 may be from the front of the display 114 (e.g., for reflective or semi-transmissive displays) or from the rear of the display 114 (e.g., for transmissive displays). The holographic display device 110 can provide uniform illumination across the display 114. In some implementations, optical waveguides can be used to uniformly illuminate the surface of the display 114, as illustrated in Figures 5D-5G. In some examples, the controller 112, irradiator 116, and display 114 can be integrated together as a single unit. This integrated single unit may, for example, include a holographic renderer 130 within the controller 112.

In some implementations, an optical diffraction device, such as a field grating device or light guide device as illustrated in Figures 5H-5K, can be configured to diffract light from the irradiator 116 onto the display 114, which then diffracts the light to the viewer's eye. In some examples, the light from the irradiator 116 can be incident on the optical diffraction device from the side at a large angle of incidence so that the irradiator 116 does not obstruct the viewer's view of the display 114. In some examples, the diffracted light from the optical diffraction device can be diffracted at an angle of incidence nearly perpendicular to the display so that the light illuminates the display relatively uniformly and diffracts to the viewer's eye with reduced loss (e.g., minimized).

Figure 1B illustrates a schematic diagram of an exemplary holographic display device 150. The holographic display device 150 may be similar to the holographic display device 110 in Figure 1A. The holographic display device 150 includes a computing architecture 152 and a display 156. The computing architecture 152 may be similar to the controller 112 in Figure 1A. The computing architecture 152 may include an array of parallel computing cores 154. The computing cores can be connected to adjacent computing cores via communication connectivity 159, for example, a USB-C connection or any other high-speed serial (or parallel) connectivity. The connectivity 159 may be included in a data distribution network where scene data 151 (e.g., scene primitives) can be distributed among the computing cores 154.

The display 156 may be similar to the display 114 in Figure 1A and may include an array of display elements 160 positioned on the backplane 158. The display elements 160 may be located in front of the backplane 158, and the computing core 154 may be located behind the backplane 158. The backplane 158 may be a substrate, such as a wafer. The computing core 154 may be on the same substrate as the display 156, or bonded to the back of the display 156.

Each computing core 154 can be connected to each tile (or array) of the display element 160. Each computing core 154 can be configured to perform calculations in parallel with one or more other computing cores on each primitive of several primitives in the scene data 151. In some examples, the computing core 154 is configured to calculate the EM field contribution from each of each primitive to each of the display elements 160 and to generate a sum of the EM field contributions from several primitives to each of the tiles of the display element 160. The computing core 154 can receive the calculated EM field contributions from other primitives to each of the tiles of the display element 160 from other computing cores in the array of computing cores 154, and generate a sum of the EM field contributions based on the received calculated EM field contributions. The computing core 154 can generate control signals for each of the tiles of the display element to modulate at least one characteristic of each of the tiles of the display element 160 based on the sum of the EM field contributions to the display element.

As described above, the computing architecture 152 can also generate a control signal to the irradiator 162 in response to determining, for example, that the calculation of the sum of the EM field contributions from several primitives to each of the display elements has been completed. The irradiator 162 emits input light 153 to illuminate the modulated display element 160, and the input light 153 is diffracted by the modulated display element 160 to form a volume light field, such as a holographic light field 155, corresponding to the scene data 151.

As illustrated in Figure 1B, the tiles of the display element 160 can be interconnected to a larger display. Correspondingly, the computing cores 154 can be interconnected for data communication and distribution. Note that the parameter that changes in holographic computation between two given display elements is their physical location. Therefore, the task of computing the hologram can be equally shared between the corresponding computing cores 154, and the entire display 150 can operate at the same speed as a single tile, regardless of the number of tiles.

Figure 1C illustrates an exemplary system 170 for displaying objects in 3D space. System 170 may include a computing device, e.g., computing device 102 in Figure 1A, and a holographic display device 172, e.g., the holographic display 110 in Figure 1A, or 150 in Figure 1B. A user can operate System 170 using input devices, e.g., a keyboard 174 and/or a mouse 176. For example, a user can create computer graphics (CG) models of 2D objects 178 and 3D objects 180 through the computing device. The computing device or holographic display device 172 may include a holographic renderer, e.g., the holographic renderer 130 in Figure 1A, for rendering the CG models and generating corresponding graphic data for the 2D objects 178 and 3D objects 180. The graphic data may include primitive data for each of the primitives corresponding to objects 178 and 180.

The holographic display device 172 may include a controller, for example, controller 112 in Figure 1A or 152 in Figure 1B, and a display 173, for example, display 114 in Figure 1A or 156 in Figure 1B. The controller can calculate the respective sums of the EM field contributions from primitives to each display element of the display 173 and generate control signals for modulating each display element based on the respective sums of the EM field contributions. The holographic display device 172 may further include an irradiator, for example, irradiator 116 in Figure 1A or irradiator 162 in Figure 1B. The controller can generate timing control signals to operate the irradiator. When light from the irradiator illuminates the surface of the display 173, the modulated display elements can propagate the light in 3D space to form a volume light field corresponding to the holographic reconstruction of the 2D view of object 178 and the holographic reconstruction of the 3D object 180. Therefore, the 2D view of object 178 and the 3D holographic reconstruction of object 180 are displayed as holographic reconstructions floating in 3D space in front of, behind, or across the display 173.

In some implementations, the computing device transmits non-primitive-based data, such as recorded optical field video, to the holographic display device 172. The holographic display device 172 can compute and generate corresponding holograms, such as a series of consecutive holograms, and display them in 3D space as corresponding holographic reconstructions. In some implementations, the computing device transmits CG holographic content to the holographic display device 172 simultaneously with live holographic content. The holographic display device 172 can also compute and generate corresponding holograms and display the content in 3D space as corresponding holographic reconstructions.

Figure 2 illustrates an exemplary configuration 200 for electromagnetic (EM) field calculations. An LCOS device, including a display 202, for example, an array of elements 204, and a list of primitives including point primitives 206, is located in 3D space 208. 3D space 208 includes a boundary surface 210. In the 3D coordinate system XYZ, a point primitive 206 has coordinate information (x, y, z). Each display element 204 is on a plane flat with respect to other display elements 204 and has a 2D position (u, v). Display elements 204 also have a location in 3D space. By mathematical point transformation, the 2D position (u, v) can be transferred to six coordinates 250 in the 3D coordinate system. That is, the surface of the display 202 forms a portion of the boundary surface 210. Therefore, the EM field contribution to the display elements from the list of primitives calculated by defining boundary conditions on the surface of the display 202 represents a portion of the total EM field contribution from the primitives to the display elements. A scaled sum of the field contributions can be obtained by multiplying the sum of the EM field contributions for each of the display elements by a scaling factor, e.g., 6, and the display elements can be modulated based on this scaled sum of field contributions.

Exemplary EM Field Contributions for Primitives Primitives can be used in computer graphics rendering. Each type of primitive in computer graphics corresponds to a discrete mathematical function that defines a single holographic primitive of the graphic elements added to a hologram in the formulation of the techniques disclosed herein. Each type of primitive can correspond to an equation for calculating the EM field contribution to the display elements. Primitives can be point primitives, line primitives, or polygonal (e.g., triangle) primitives. As illustrated below, analytical equations can be derived by calculating the EM field propagation from the corresponding primitive to the display elements of the display.

Figure 3A illustrates exemplary EM propagation from point primitive 304 to element 302 of display 300. In the 3D coordinate system XYZ, we assume that the z coordinate is 0 across display 300, meaning that negative z values are behind display 300 and positive z values are in front of display 300. Point primitive 304 has coordinates (x, y, z), and display element 302 has coordinates (u, v, 0). The distance d _uv between point primitive 304 and display element 302 can be determined based on their coordinates.

The point primitive 304 can be considered as a point charge with a time-varying amplitude. According to electromagnetic theory, the electric field E generated by such a point charge is
It can be expressed as follows:
In the formula, λ represents the wavelength of the EM wave, and d represents the distance from the point charge.

Therefore, the electric field E in the display element (u _, v) is,
It can be expressed as follows:
In the formula, I represents the relative intensity of the holographic primitive electric field in the display element contributed from the point primitive 304.

As discussed above with respect to Figure 2, the surface of the display 300 forms only a portion of the boundary surface of the EM field. The scale coefficient S is applied to the electric fields E _{u, v} , and the scaled electric field E _φ (u, v) can be obtained in the display element that adjusts the partial boundary as follows.

Figure 3B illustrates an example of EM propagation from a line primitive 306 to a display element 302 of a display 300 in a 3D coordinate system XYZ. As described above, the display element 302 may have coordinates (u, v, 0) where z = 0. The line primitive 306 has two endpoints _P0 with coordinates (x ₀ , y ₀ , z ₀ ) and _P1 with coordinates (x ₁ , y ₁ , z ₁ ). The distance _d0 between endpoint _P0 and the display element can be determined based on their coordinates. Similarly, the distance _d1 between endpoint _P1 and the display element can be determined based on their coordinates. The distance _d01 between _the two endpoints P0 and _P1 can also be determined, for example, _d01 = _d1 - _d0 .

As discussed above, line primitives can be treated as superpositions or linear deformations, and the corresponding analytical formula for a line primitive as a linear aperture can be obtained as a dispersed delta function in space. This analytical formula can be a closed equation for a continuous 3D line segment as a hologram.

Figure 3C illustrates exemplary EM propagation from a triangular primitive 308 to a display element 302 of a display 300 in a 3D coordinate system XYZ. As described above, the display element 302 may have coordinates (u, v, 0) where z = 0. The triangular primitive 308 has three endpoints, _P0 ( _x0 , _y0 , _z0 ), _P1 ( _x1 , _y1 , _z1 ), and _P2 ( _x2 , _y2 , _z2 ). The distances _d0 , _d1 , and _d2 between the display element and the endpoints _P0 , _P1 , and _P2 can be determined based on their respective coordinates.

Similar to the line primitives in Figure 3B, the triangular primitives can be treated as continuous openings in space, and the analytical formula for the EM field contribution of the triangular primitives to the display element can be obtained by integration. This can be simplified to obtain a formula for efficient calculation.

Exemplary Calculation for Primitives As discussed above, a controller, for example, controller 112 in Figure 1A, can calculate the EM field contribution from primitives to display elements based on the analytical formula that can be determined as shown above. As an example, the EM field contribution for a line primitive is calculated as follows.

Each display element within a display has a physical location in space, and each display element lies on a flat plane relative to other display elements. Assuming that the display elements and their controllers are laid out conventionally in the display and memory devices, a simple mathematical point transformation can be used to translate the logical location of a given display element to its actual physical location in space, based on its logical memory address in the processor. Therefore, when the logical memory address of a display element is looped over in the processor's logical memory space, the corresponding actual physical location in space across the surface of the display can be identified.

As an example, if the display has a 5 μm pitch in both x and y directions, each logical address increment can move 5 μm in the x direction. Upon reaching the display's x-resolution limit, the next increment moves back to the initial x physical location and increments the y physical location by 5 μm. A third spatial coordinate z can be assumed to be zero across the display surface, meaning that negative z values are behind the display and positive z values are in front of the display.

To begin the line calculation, we can determine that the types of scaled physical distances between the current display element and each of the two points of the line primitive are _d0 and _d1 . In fact, _d0 and _d1 can be calculated once per primitive, since any subsequent calculation of the distance across the display element is a small perturbation of the initial value. Thus, this calculation is performed in one dimension.

The exemplary calculation process for each primitive is shown in the following calculation code:
DD=f(d1,d0),
iscale=SS*COLOR*Alpha1,
C1=-2*iscale*sin(DD/2)*sin(Alpha2)*cos(Alpha3),
C2 can include -2 * `iscale * sin(DD/2) * sin(Alpha2) * sin(Alpha4),
In the formula, SS, Alpha1, Alpha2, Alpha3, and Alpha4 are pre-calculated constants, COLOR is an RGB color value passed as a primitive, and all values are scalar single-precision floats. Calculation efficiency can be improved by looking up both sine and cosine functions in a table stored in the controller.

Next, the results in C1 and C2 can be accumulated, for example, in an accumulator for the display elements, for each primitive in each display element, and normalized once at the end of the calculation for the display elements. At this point, as described above, the controller can transmit a first control signal to the display elements to modulate them based on the calculated results, and transmit a second control signal to the irradiator to turn them on to emit light. Thus, the holographic reconstruction (or holographic light field) is visible to the viewer. When irradiated, the modulated display elements can cause the light to generate sharp and continuous color lines in three-dimensional space.

In some implementations, the computed code may include, for example, a hexadecimal code at the beginning of the code to clear previous accumulations in the accumulator. The computed code may also include, for example, a hexadecimal code at the end of the code to store the accumulator results in their respective memory buffers for each display element. In some implementations, a computing device, for example, computing device 102 in Figure 1A, transmits several background or static primitive hexadecimal codes to a controller at application startup or at intervals that display frames that do not affect the primary display frame rate. The computing device can then transmit potentially one or more combinations of hexadecimal codes, along with other foreground or dynamic primitives, at a much higher rate to a controller that can form corresponding control signals for modulating the display elements of the display.

The calculation process can be orders of magnitude simpler and faster than the most efficient line drawing routines in conventional 2D display technology. Furthermore, this calculation algorithm scales linearly with several display elements. Therefore, scaling the controller's computing units as a 2D network processing system can keep up with the increasing surface area calculation needs of displays.

Exemplary Calculation Implementation: A Maxwell holographic controller, for example, controller 112 in Figure 1A, can calculate the EM field contribution from primitives to display elements based on an analytical formula that can be determined as shown above. The controller can be implemented, for example, in an ASIC, FPGA, or GPU, or any combination thereof.

In modern GPU pipelines, the GPU takes a description of a geometric figure, as well as vertex and fragment shader programs, to generate color and depth pixel outputs on one or more output image surfaces (called rendering targets). The process involves a massive fan-out of information where the geometry is unfolded into shaded fragments, followed by a visibility test to select which of these fragments need to be worked on. A fragment is a record containing all the information involved in shading its sample points, such as the centroid coordinates of a triangle, interpolated values like color or texture coordinates, and surface derivatives. The visibility test is the process of creating these records and then rejecting any records that do not contribute to the final image. Fragments that pass the visibility test can be packed into work groups called wavefronts or warps, which are executed in parallel by the shader engine. These generate output values that are written to memory as pixel values, ready for display, or ready for use as input textures for later rendering passes.

Maxwell holography can significantly simplify the rendering process. In Maxwell's holographic computation, any primitive can contribute to any display element. There is no need to extend geometry to pixels, nor is there a need to apply visibility tests before packing wavefronts. This also eliminates the need for decision-making or communication between Maxwell holographic pipelines, allowing computations to be considered in parallel with several possible solutions, each tailored to speed, cost, size, or energy optimization. The graphics pipeline is significantly shorter, with fewer intermediate steps, no data copying or movement, and fewer decisions to reduce latency between starting drawing and getting the result ready for display. This allows Maxwell holographic rendering to create extremely low-latency displays. As will be discussed below, this allows Maxwell holographic computations to improve accuracy and optimize computation speed, for example, by using fixed-point arithmetic in the Maxwell holographic pipeline, and by optimizing mathematical functions.

When calculating the EM contribution from each primitive for each display element (or "fazel") using fixed-point arithmetic, the intermediate calculation involves generating very large numbers. These large numbers require special handling because they also need to retain fractional parts during the calculation.

Floating-point values have the drawback of having the precision closest to the origin (zero on the number line), and as you move away from the origin, you lose one bit of precision for every power of two. For numbers close to the range [-1, 1], the precision of floating-point values is exquisite, but when you reach tens of millions of numbers, for example, when a single-precision 32-bit IEEE-754 floating-point value reaches the point where no decimal digits remain, the entire mantissa (also known as the mantissa) is used to represent the integer part of the value. However, what Maxwell's holography is particularly interested in preserving is the fractional part of large numbers.

In some cases, fixed-point numbers are used in Maxwell holographic calculations. Fixed-point representation is a number where the decimal point does not change on a case-by-case basis. By selecting the correct number of bits for the integer and fractional parts of a number, the same number of fractional bits can be obtained regardless of the magnitude of the number. Fixed-point numbers are represented as integers with an implicit scaling factor; for example, 14.375 can be represented as the number 3680 (0000111001100000 binary) in a 16-bit fixed-point value with eight fractional bits. This can also be represented as the fixed-point "unsigned 16.8," or simply u16.8. Negative numbers can have one additional sign bit and are stored in "two-sign" form. In this way, the precision of calculations can be greatly improved.

Optimization for Mathematical Functions As shown above, Maxwell holographic computation involves the use of transcendental mathematical functions, such as the sine function, cosine function, and arc tangent function. On a CPU, these functions are implemented as floating-point library functions that can use special CPU instructions, or on a GPU, as floating-point units in the GPU. These functions are written to accept arguments as floating-point numbers, and the results are returned in the same floating-point representation. These functions are built for the general case to be exact when the float is exact, rounded correctly, and to handle all edge cases of the floating-point representation (infinity, NaN, signed zero, and denormalized float).

In Maxwell holographic computation, floating-point representations do not require the use of denormalized floats for gradual underflow, handling of NaN results from operations such as division by zero, changing floating-point rounding modes, or raising floating-point exceptions to the operating system. All of this allows for the simplification (and/or optimization) of transcendental mathematical functions, as discussed below, for example.

In some cases, it is possible to optimize the function to take arguments in a single fixed-point format and return the values to different levels of precision, for example, input s28.12 and output s15.14. This can be particularly desirable when calculating sine values of tens of millions, where the input argument can be large, but the output only needs to represent the arctangent, which can accept values within the range [-1, 1] or any value, although it may return values within the range [-π/2, π/2].

In some cases, depending on the relevant input range, optimizations can be made to freely implement the transcendental function as a fully enumerated lookup table, an interpolated table, a semi-table-based polynomial function, or a semi-table-based fully minimal polynomial. Furthermore, it becomes possible to apply special range reduction methods to handle large inputs that general-purpose GPU pipeline computations can skip for speed.

In some cases, an alternative optimization can transform trigonometric calculations from the range [-π, π] to a signed 2 representation in the range [-1, 1], which has the advantage of not requiring the expensive 2π division operation.

Exemplary Implementations for Occlusion Occlusion is often considered a difficult and important topic in computer graphics, and even more so in computational holography. This is because, at least in some cases, the occlusion problem in projection CGI is static, whereas what is hidden and visible in a holographic system depends on the viewer's location, orientation, and direction. G-S holography or its derivative wave approaches have been developed to address holographic occlusion. However, masking or blocking contributions from parts of a scene behind other parts of the scene can be very complex and computationally expensive in G-S methodologies.

In Maxwell holography, the occlusion problem can be handled relatively easily because the correspondence between display elements (e.g., fesel) and primitives is completely deterministic and trivial. For example, whether a given display element contributes to the reconstruction of a given primitive can be determined when the calculation of the given primitive is performed. If, after determining that some display elements do not contribute to a given primitive due to occlusion, the sum of the EM contributions to one of the display elements is calculated, the EM contribution from the given primitive is omitted from the calculation of the sum of the EM contributions to that one of the display elements.

For illustrative purposes only, Figures 3D-3F demonstrate the determination of display elements that do not contribute to a given primitive (the point in Figure 3D, the line in Figure 3E, and the triangle in Figure 3F) using a line primitive as an occluder. The line primitive has a start point O1 and an end point O2.

As illustrated in Figure 3D, the point primitive P0 is behind the occluder and close to the display. By extending the lines connecting O1-P0 and O2-P0, the range of display elements D1-D2 in the display that do not contribute to the reconstruction of point primitive P0 is determined.

In some examples, the coordinate information of O1, O2, and P0, stored in the "Z" buffer calculated by the GPU (e.g., GPU 108 in Figure 1A), is known before the scene is transmitted to the Maxwell Holographic Controller (e.g., Controller 112 in Figure 1A). For example, in the XZ plane at y=0, the coordinate information could be O1(Ox1, Oz1), O2(Ox2, Oz2), and P0(Px, Pz), where Oz1=Oz2=Oz. Based on the coordinate information, the coordinate information of D1 and D2 is:
It can be determined that Dx1 = Px + ρ(Px - Ox2) and Dx2 = Dx1 + ρ(Ox2 - Ox1) (4),
In the equation, ρ = Pz/(Oz - Pz) and Dz1 = Dz2 = 0.

The information in D1 and D2 can be stored as additional information in the "S" buffer of the Maxwell holographic controller, in addition to the information in the Z buffer of the point primitive P0. In this way, the contribution of a specific display element (within the range of D1-D2) to a specific primitive P0 in the indexed primitive list can be trivially masked using this additional information.

Figure 3E illustrates how to determine how a particular display element contributes to a line primitive that has an occluder in front of (or ahead of) it. By connecting a particular display element D0 to the start point _O1 and end point _O2 of the occluder, two point primitives P1 and P2 on the line primitive are determined to be intersections. Therefore, the particular display element D0 does not contribute to the reconstruction of the portion of the line primitive from P1 to P2. Consequently, when calculating the total EM contribution to the particular display element D0, the EM contribution from the portion of the line primitive P1-P2 is not calculated.

This can be implemented in two ways. In the first method, the EM contributions from sub-sections P0-P1 and P2-Pn to a specific display element D0 are summed as the EM contribution of the line primitive to that specific display element D0, by considering occlusion from occluders. In the second method, the EM contribution from the entire line primitive P0-Pn is calculated together with the EM contribution from sub-sections P1-P2, and by considering occlusion from occluders, the difference between the two calculated EM contributions can be considered as the EM contribution of the line primitive to the specific display element D0. The coordinate information of P1 and P2, or sub-sections P1-P2, can be stored in the Maxwell Holographic Controller's "S" buffer, along with occluder information and other information in the GPU's "Z" buffer, as part of the line primitive that does not contribute to the specific display element D0.

Figure 3F illustrates how to determine how a particular display element contributes to a triangular primitive that has an occluder in front of it. By connecting a particular display element D0 to the start point O1 and end point O2 of the occluder, the four point primitives P1, P2, P3, and P4 on the sides of the triangular primitive are determined to be intersections. Therefore, the particular display element D0 does not contribute to the reconstruction of the portion of the triangular primitive enclosed by points P1, P2, P3, P4, and _PC. Consequently, when calculating the total EM contribution to the particular display element D0, the EM contribution from the portion of the triangular primitive P1-P2-P3-P4- _PC is not calculated. In other words, by considering the occlusion of occluders, only the EM contributions from the first triangle formed by points P _A , P1, and P2, and the second triangle formed by points P _B , P3, and P4 are summed as the EM contribution of the triangular primitive P _A - _{P B} - P _C. The coordinate information of P1, P2, P3, and P4 or the triangular primitives P _A - P1 - P2 and P _B - P3 - P4 can be stored in the Maxwell Holographic Controller's "S" buffer as part of the triangular primitive P _A - _{P B} - P _C contributing to a specific display element D0, along with the occluder information and other information in the GPU's "Z" buffer.

The implementation of occlusion in Maxwell holography allows for the conversion of the "Z" buffer in the GPU to the "S" buffer in the Maxwell holographic controller, enabling the masking of the contribution of specific primitives (or specific parts of primitives) to specific display elements within an indexed primitive list. This not only provides accurate and physically correct occlusion but also saves computation time by allowing primitives that do not contribute to a given display element to be ignored, enabling computation to move on to the next display element. The "S" buffer can contain additional information related to the diffraction efficiency of the display.

The "S" buffer can also contain rendering features such as holographic specular highlights where the surface reflectivity depends on the viewing angle. In conventional CGI, specular highlights depend only on the orientation of the rendered object, but in the Maxwell holographic context, the direction in which the object is displayed also matters. Therefore, geometric specular information can be encoded in the "S" buffer as an additive (specular) contribution rather than a subtractive (occlusion) contribution. In Maxwell holography, the mathematics of holographic specular highlights can be substantially the same as that of holographic occlusion.

Exemplary Implementation for Stitching: When light illuminates a display modulated with EM contributions from a list of primitives of a 3D object, the modulated display causes the light to propagate in different directions, forming a volume light field corresponding to the primitives. The volume light field is a Maxwell holographic reconstruction. Two adjacent primitives within a 3D object, for example, two triangle primitives, share a common edge (e.g., a border or surface). During reconstruction, a stitching problem may arise, as the reconstruction of two adjacent primitives can double the light intensity of the common edge. This can affect the appearance of the reconstructed 3D object.

As illustrated in Figure 3G, to address the stitching problem in Maxwell holography, adjacent primitives can be scaled down by a predetermined coefficient so that gaps can be formed between them. In some cases, instead of scaling down two adjacent primitives, only one primitive or a portion of a primitive is scaled down. For example, the lines of a triangular primitive can be scaled down so that they separate from another triangular primitive. In some cases, scaling may include scaling different parts of a primitive using different predetermined coefficients. The scaling can be designed so that the gaps are large enough to separate adjacent primitives and minimize the stitching problem, and small enough so that the reconstructed 3D object appears seamless. The predetermined coefficients can be determined based on display and viewer information, such as the maximum spatial resolution of the holographic light field, and the minimum distance from the viewer to that portion of the primitive if that portion is fully or partially behind the display.

In some cases, the scaling operation can be applied to primitive data of primitives acquired from a holographic renderer, for example, the holographic renderer 130 in Figure 1A, and the scaled primitive data of the primitives is sent to a Maxwell holographic controller, for example, the controller 112 in Figure 1A. In some cases, the controller can perform the scaling operation on the primitive data acquired from the holographic renderer before calculating the EM contribution of the primitives to the display elements of the display.

Exemplary Implementations for Texture Mapping Texture mapping is a technique developed in computer graphics. The basic idea is to take a source image and apply it as a decal to the surface of a CGI system, enabling the rendering of details into the scene without the need to add complex geometry. Texture mapping can include techniques for creating realistic illumination and surface effects within a CGI system and can universally refer to the application of surface data to a triangular mesh.

Maxwell holography allows for the rendering of flat, shaded, and interpolated triangular meshes in true 3D using analytical relationships between arbitrary triangles in space and phase diagrams on a holographic device. However, for compatibility with modern rendering engines, the ability to map surface information of these triangles is desirable. This presents a practical problem in that the speed of the method is derived from the existence of analytical mapping that does not allow for data-driven amplitude changes.

The Discrete Cosine Transform (DCT) is an image compression technique that can be thought of as a real-valued version of the Fast Fourier Transform (FFT). The DCT relies on an encoding-decoding process that assigns weights to the cosine harmonics within a given image. The result of the encoding is a set of weights equal to the number of pixels in the original image, and no information is lost when reconstructing the image using all the weights. However, for many images, an acceptable reconstruction can be performed using a small subset of weights, allowing for a large compression ratio.

The two-dimensional DCT decoding (rendering) process involves a weighted double sum across all DCT weights and all destination pixels. This can be applied to Maxwell Holography for texture mapping. In Maxwell Holography, triangle rendering involves a "spiked" double integral in phase space to determine the phase contribution of individual Fessels to the triangle in question. The integral is folded into a double sum that mirrors that in DCT reconstruction, and then the analytical triangle equation can be re-derived with respect to the DCT weights. This implementation of DCT techniques in Maxwell Holographic computation allows for the drawing of complete texture-mapping triangles, application of image compression to the rendered texture triangle data, and utilization of existing toolsets that automatically compress texture and image data using DCT, such as JPEG.

In some implementations, to render Maxwell holographic textured triangles, the desired spatial resolution for mapping on a given surface is first calculated. Next, a texture with resolution is supplied and compressed with angle and origin information to obtain DCTs correctly oriented on the triangles. Then, a list of triangle angles and DCT weights is included in an indexed primitive list and sent to the Maxwell holographic controller. DCT weights can be included in the EM contribution of the triangle primitive to each display element. Textured triangles can be n times slower than flat triangles, where n is the number of (non-zero) DCT weights sent with the primitives. Modern techniques for "fragment shading" can be implemented in Maxwell holographic systems, where the DCT coding step replaces the filtering step for conventional projection rendering.

As an example,
M and N are the corners of the rectangular image, and (p, q) is the DCT term.

By decoding, the amplitude value A _mn is,

When calculating the EM contribution of a textured triangle primitive to a display element (e.g., a fesel), the DCT term with the corresponding DCT weight A* _mn is:
It can be included in the calculation as shown above.
In the formula, X and Y are the angles of a triangle in the coordinate system, T corresponds to the EM contribution of the triangular primitive to the display element, and φ _pq is the partial contribution of the non-zero term B _pq in the DCT. The number of (p,q)DCT terms can be selected by considering both information loss and information compression in reconstruction.

Exemplary Process Figure 4 is a flowchart of an exemplary process 400 for displaying an object in 3D. Process 400 may be performed by a controller for the display. The controller may be controller 112 in Figure 1A or 152 in Figure 1B. The display may be display 114 in Figure 1A or 156 in Figure 1B.

Data containing the primitive data for each primitive corresponding to an object in 3D space is acquired (402). This data can be acquired from a computing device, for example, computing device 102 in Figure 1A. The computing device can process the scene to generate primitives corresponding to the objects. The computing device may include a renderer for generating primitive data for the primitives. In some implementations, the controller generates the data itself, for example, by rendering the scene.

A primitive can include at least one of a point primitive, a line primitive, or a polygon primitive. The list of primitives may be indexed in a specific order, for example, that allows for the reconstruction of an object. Primitive data may include color information having at least one of a texture color, a gradient color, or a constant color. For example, a line primitive may have at least one of a gradient color, a texture color, or a constant color. A polygon primitive may also have at least one of a gradient color, a texture color, or a constant color. Primitive data may also include the primitive's texture information and/or shading information on one or more surfaces of the primitive (e.g., a triangle). The shading information may include at least one modulation of color or brightness on one or more surfaces of the primitive. Primitive data may also include the coordinate information of each primitive in a 3D coordinate system.

A display can include several display elements, and a controller can include several computing units. The coordinate information of each display element in a 3D coordinate system can be determined based on the coordinate information of each primitive in a list of primitives in the 3D coordinate system. For example, the distance between the display and the object corresponding to the primitive can be predetermined. Based on the given distance and the primitive's coordinate information, the coordinate information of the display element can be determined. The coordinate information of each display element can correspond to the logical memory address of the element stored in memory. In this way, when the controller loops through the logical memory addresses of the display elements in the controller's logical memory space, it can identify the corresponding actual physical location of the display element in space.

The EM field contribution from each primitive to each display element is determined by calculating the propagation of the EM field from the primitive to the element in a 3D coordinate system (404). The EM field contribution may include at least one of either a phase contribution or an amplitude contribution.

As illustrated above with respect to Figures 3A-3C, at least one distance between a primitive and a display element can be determined based on the coordinate information of each display element and the coordinate information of each primitive. In some cases, for each primitive, at least one distance may be calculated or determined only once. For example, the controller can determine a first distance between a first primitive and a first element of the display elements based on the coordinate information of each first primitive and each first element, and determine a second distance between a first primitive and a second element based on the first distance and the distance between the first and second elements. The distance between the first and second elements can be predetermined based on the pitch of multiple elements of the display.

The controller can determine the EM field contribution from the primitive to the display element based on a predetermined equation for the primitive and at least one distance. In some cases, as illustrated above with respect to Figures 3A-3C, the predetermined equation can be determined by analytically calculating the EM field propagation from the primitive to the element. In some cases, the predetermined equation can be determined by solving Maxwell's equations. In particular, Maxwell's equations can be solved by providing boundary conditions defined on the surface of the display. The boundary conditions can include Dirichlet boundary conditions or Cauchy boundary conditions. The primitive and the display element are in 3D space, and the surface of the display forms part of the interface of 3D space. The predetermined equation can include at least one of functions, including sine, cosine, and exponential functions. During calculation, the controller can identify at least one value of a function in a table stored in memory, which can improve the calculation speed. The controller can determine the EM field contribution of each primitive to each display element by simultaneously determining the second EM field contribution from the second primitive to the display element and the first EM field contribution from the first primitive to the display element.

For each display element, the sum of the EM field contributions to the display element is generated from the list of primitives (406).

In some implementations, the controller determines the first EM field contribution from the primitive to the first display element, sums the first EM field contributions for the first element, determines the second EM field contribution from the primitive to the second display element, and sums the second EM field contributions for the second display element. The controller may include several computing units. The controller can determine the EM field contribution from the first primitive to the first element using the first computing unit, in parallel with the second computing unit determining the EM field contribution from the second primitive to the first element.

In some implementations, the controller determines the first EM field contribution from the first primitive to each display element, and then determines the second EM field contribution from the second primitive to each display element. Next, the controller accumulates the EM field contributions for each display element by adding the second EM field contributions to the first EM field contributions for each display element. In particular, the controller can determine the first EM field contribution from the first primitive to each display element by using the first computing unit, in parallel with determining the second EM field contribution from the second primitive to each display element by using the second computing unit.

The first control signal is transmitted to the display and is for modulating at least one characteristic of each display element based on the sum of the field distributions to the display elements (408). The at least one characteristic of an element includes at least one of refractive index, amplitude exponent, birefringence, or delay.

The controller can generate a control signal for each display element based on the sum of the EM field contributions from the primitives to the element. Each control signal is intended to modulate at least one characteristic of the element based on the sum of the EM field contributions from the primitives to the element. That is, the first control signal includes the respective control signals for each display element.

In some examples, displays are controlled by electrical signals. Each control signal, then, can be an electrical signal. For example, an LCOS display includes an array of microelectrodes, the voltage of which is individually controlled as element intensity. An LCOS display can be filled with a birefringent liquid crystal (LC) composition that changes its refractive index as the applied voltage changes. Therefore, each control signal from the controller can control the relative refractive index across the display elements, and thus the relative phase of light passing through or reflected by the display.

As discussed above, the display surface forms part of the interface. The controller can obtain a scaled sum of field contributions by multiplying the sum of each element's field contributions by a scaling factor, and then generate the respective control signals based on this scaled sum of field contributions for each element. In some cases, the controller can, for example, normalize the sum of field contributions for each element across all elements, and then generate the respective control signals based on this normalized sum of field contributions for each element.

A second control signal is transmitted to the illuminator as a control signal to turn on the illuminator in order to illuminate the modulated display with light (410). The controller may generate and transmit the second control signal in response to determining the completion of obtaining the sum of the field contributions for each of the display elements. Due to time symmetry (or energy conservation), the modulated elements of the display can propagate light in different directions to form a volume light field corresponding to an object in 3D space. The volume light field can correspond to a solution of Maxwell's equations with boundary conditions defined by the modulated elements of the display.

In some implementations, the irradiator is coupled to a controller via a memory buffer configured to control the amplitude or brightness of one or more light-emitting elements within the irradiator. The memory buffer for the irradiator may be smaller in size than the memory buffer for the display. Some of the light-emitting elements within the irradiator may be smaller than some of the elements of the display. The controller may be configured to operate one or more of the light-emitting elements of the irradiator simultaneously.

In some examples, the illuminator includes two or more light-emitting elements, each configured to emit light of a different color. The controller can be configured to control the illuminator to sequentially modulate the display with information associated with a first color during a first period, and to modulate the display with information associated with a second color during a second consecutive period, and to sequentially turn on the first light-emitting element to emit light of the first color during the first period, and the second light-emitting element to emit light of the second color during the second period. In this way, multi-color objects can be displayed in 3D space.

In some examples, the display has a resolution small enough to diffract light. An irradiator can cause the display to emit white light that diffracts into light of different colors, thereby allowing it to display multicolored objects.

Exemplary Systems Figures 5A to 5K show exemplary implementations of systems for 3D displays. Any one of the systems can correspond, for example, to system 100 in Figure 1A. Figures 5A and 5B show exemplary systems having a reflective display with front illumination. Figure 5C shows exemplary systems having a transmissive display with back illumination. Figures 5D and 5E show exemplary systems having a transmissive display with waveguide illumination. Figures 5F and 5G show exemplary systems having a reflective display with waveguide illumination. Figures 5H and 5I show exemplary systems having a reflective display with optical diffraction illumination using a transmissive grating structure (Figure 5H) and a reflective grating structure (Figure 5I). Figures 5J and 5K show exemplary systems having a transmissive display with optical diffraction illumination using a reflective grating structure (Figure 5J) and a transmissive grating structure (Figure 5K).

Figure 5A illustrates a system 500 with a reflective display having front illumination. The system 500 includes a computer 502, a controller 510 (e.g., an ASIC), a display 512 (e.g., an LCOS device), and an irradiator 514. The computer 502 may be the computing device 102 in Figure 1A, the controller 510 may be the controller 112 in Figure 1A, the display 512 may be the display 114 in Figure 1A, and the irradiator 514 may be the irradiator 116 in Figure 1A.

As illustrated in Figure 5A, the computer 502 includes an application 504 having a renderer 503 for rendering a scene of objects. The rendered scene data is processed by the video driver 505 and then by the GPU 506. The GPU 506 may be the GPU 108 in Figure 1A and can be configured to generate a list of primitives corresponding to the scene and their respective primitive data. For example, the video driver 505 can be configured to process the rendered scene data and generate a list of primitives. As described above, the GPU 506 may include a conventional 2D renderer, for example, the conventional 2D renderer 120 in Figure 1A, for rendering primitives into a list of items to be drawn on the 2D display 508. The GPU 506 or controller 510 may include a holographic renderer, for example, the holographic renderer 130 in Figure 1A, for rendering the list of primitives into graphic data displayed by the display 512.

The controller 510 is configured to receive graphic data from the computer 502, calculate the EM field contribution to each element of the display 512 from a list of primitives, and generate the sum of the EM field contributions from the primitives to each element. The controller 510 can generate a control signal for each display element to modulate at least one characteristic of the display element. The controller can transmit the control signals to the display elements of the display 512 through the memory buffer 511 for the display 512.

The controller 510 can also generate and transmit control signals, such as irradiation timing signals, to operate the irradiator 514. For example, the controller 510 can generate and transmit a control signal in response to determining that the calculation of the total EM field contribution from the primitive to the display element is complete. As described above, the controller 510 can transmit the control signal to the irradiator 514 via a memory buffer. The memory buffer can be configured to control the amplitude or brightness of the light-emitting elements in the irradiator 514 and to operate the light-emitting elements simultaneously or sequentially.

As illustrated in Figure 5A, the irradiator 514 can emit a collimated light beam 516 incident on the front of the display 512 at an incident angle ranging from 0 degrees to approximately ±90 degrees. The emitted light beam is diffracted from the display 512 to form a holographic light field 518 corresponding to the object, which can be viewed by the viewer.

Figure 5B illustrates another system 520, which includes another reflective display 524 with front illumination. Compared to system 500 in Figure 5A, system 520 has a larger reflective display 524. To accommodate this, or for other packaging or aesthetic reasons, the display controller 522 is contained in a housing that may be a support or enclosure for the illuminator 526. The controller 522 is similar to the controller 510 in Figure 5A and may be configured to receive graphic data from the computer 521, calculate the EM field contribution from primitives to each of the display elements of the display 524, and generate the respective sums of the EM field contributions from primitives to each of the display elements. The controller 522 then generates a respective control signal for each of the display elements to modulate at least one characteristic of the display elements and transmits the respective control signals to the display elements of the display 524 through a memory buffer 523 for the display 524.

The controller 522 also transmits control signals to the irradiator 526 to activate it. The irradiator 526 emits a divergent or semi-collimated light beam 527 that covers the entire surface of the display 527. The light beam 524 is diffracted by the modulated display 524 to form a holographic light field 528.

Figure 5C illustrates a system 530 comprising a transmissive display 534 with back illumination. The transmissive display 534 may be, for example, a large display. The system 530 includes a controller 532, which may be similar to the controller 510 in Figure 5A. The controller 532 may be configured to receive graphic data from a computer 531, calculate the EM field contribution from primitives to each of the display elements of the display 534, and generate the sum of the respective EM field contributions from primitives to each of the display elements. The controller 532 then generates a respective control signal for each of the display elements to modulate at least one characteristic of the display element, and transmits the respective control signals to the display elements of the display 534 through a memory buffer 533 for the display 534.

The controller 532 also transmits control signals to the irradiator 536 to activate it. Unlike system 500 in Figure 5A and system 520 in Figure 5B, the irradiator 536 in system 530 is positioned behind the back of the display 534. To cover the large surface area of the display 534, the irradiator 536 emits a divergent light beam 535 or a semi-collimated light beam 535 to the back of the display 534. The light beam 535 is transmitted through the modulated display 534 and diffracted to form a holographic light field 538.

Figure 5D illustrates another system 540, which includes a transmissive display 544 with waveguide irradiation. System 540 also includes a controller 542 and an irradiator 546. The controller 542 may be similar to the controller 510 in Figure 5A and can be configured to receive graphic data from a computer 541, perform calculations on the graphic data, generate and transmit control signals for modulation to the display 544, and generate and transmit timing signals to activate the irradiator 546.

The irradiator 546 may include a light source 545 and may include or optically mount a waveguide 547. Light emitted from the light source 545 can be coupled to the waveguide 547, for example, from the side cross-section of the waveguide. The waveguide 547 is configured to guide the light so as to uniformly illuminate the surface of the display 544. The light guided by the waveguide 547 enters the back of the display 544, passes through the display 544, and is diffracted by the display 544 to form a holographic light field 548.

Unlike system 500 in Figure 5A, 520 in Figure 5B, and 530 in Figure 5C, in system 540, the controller 542, display 544, and waveguide 547 are integrated together into a single unit 550. In some cases, the waveguide 547 and light source 545 can be integrated as a planar active waveguide irradiator, which can further increase the degree of integration of the single unit 550. As discussed above, the single unit 550 can be connected or tiled with other similar units 550 to form a larger holographic display device.

Figure 5E illustrates another system 560, which includes another transmissive display 564 with waveguide irradiation. Compared to system 540, the transmissive display 564 can potentially accommodate a larger display than the transmissive display 544. For example, the transmissive display 564 can have a larger area than the controller 562, and to accommodate this, the controller 562 can be positioned away from the display 564. System 560 includes an irradiator 566 having a light source 565 and a waveguide 567. The waveguide 567 is integrated with the display 564, for example, optically mounted on the back of the display 564. In some implementations, the display 564 may be manufactured on the front side of the substrate, and the waveguide 567 may be manufactured on the back side of the substrate.

The controller 562 may be similar to the controller 510 in Figure 1A. It is configured to receive graphic data from the computer 561, perform calculations on the graphic data, generate a control signal for modulation, transmit it to the display 564 via the memory buffer 563, and generate and transmit a timing signal to activate the light source 565. The light emitted from the light source 565 is guided in the waveguide 567, illuminating the back of the display 564, passing through the display 564, and diffracting to form a holographic light field 568.

Figure 5F illustrates another system 570, which includes a reflective display 574 with waveguide irradiation. The reflective display 574 may be, for example, a large display. The waveguide 577 of the irradiator 576 is positioned on the front of the reflective display 574. A controller 572, similar to the controller 510 in Figure 5A, can be configured to receive graphic data from a computer 571, perform calculations on the graphic data, generate and transmit modulation control signals to the display 574 via a memory buffer 573, and generate and transmit timing signals to activate the light source 575 of the irradiator 576. Light coupled from the waveguide 577 of the irradiator 576 is guided to enter the front of the display 574, where it is diffracted by the display 574 to form a holographic light field 578.

Figure 5G illustrates another system 580, which includes a reflective display 584 having a different type of waveguide illumination using a waveguide device 588. A controller 582, similar to the controller 510 in Figure 5A, is configured to generate and transmit control signals corresponding to holographic data (images and/or video) for modulation of the display 584, and to transmit timing signals to operate the irradiator 586. The irradiator 586 can provide light of one or more colors that can be parallel. The waveguide device 588 is positioned in front of the irradiator 586 and the display 584. The waveguide device 588 may include an input coupler 588-1, a waveguide 588-2, and an output coupler 588-3. The input coupler 588-1 is configured to couple collimated light from the irradiator 586 to the waveguide 588-2. The light then travels through the waveguide 588-2 via total internal reflection and enters the output coupler 588-3 at the end of the waveguide 588-2. The output coupler 588-3 is configured to couple the light to the display 584. The light then illuminates the display elements of the display 584, which are modulated with the corresponding control signal. It is diffracted by the reflective display 584 and reflected through the waveguide device 588 (e.g., the output coupler 588-3) (e.g., by the back mirror of the display 584) to form a holographic light field corresponding to the holographic data in front of the viewer.

In some examples, light is coupled by output coupler 588-3 at an angle perpendicular to the front of the waveguide device 588 and/or reflective display 584. In some examples, each of input coupler 588-1 and output coupler 588-2 may include a grating structure, such as a Bragg grating. Input coupler 588-1 and output coupler 588-2 may include similar diffraction gratings with different fringe inclination angles. In some examples, irradiator 586 provides monochromatic light, and input coupler 588-1 and output coupler 588-2 include colored diffraction gratings. In some examples, irradiator 586 provides multiple colored light beams, such as red, green, and blue light beams, and input coupler 588-1 and output coupler 588-2 may include a multilayer stack (or a single layer with three corresponding diffraction gratings) of three corresponding diffraction gratings that couple different colored light beams into or out, respectively.

Figure 5H illustrates another system 590, which includes a reflective display 594 having optical diffraction irradiation using an optical diffraction device 598. The optical diffraction device 598 can be considered a light guide device for guiding light. The optical diffraction device 598 may be a transmission field grating-based structure that may include one or more transmission holographic gratings. The reflective display 594 may be a reflective LCOS device. A controller 592, similar to the controller 510 in Figure 5A, may be configured to receive graphic data corresponding to one or more objects from a computer 591, perform calculations on the graphic data, generate control signals for modulation, and transmit them to the display 594 through a memory buffer 593. The controller 592 may also be coupled to an irradiator 596 and configured to provide timing signals to actuate the irradiator 596 to provide light. The light is then diffracted by the optical diffraction device 598 and incident on the display 594, and then diffracted by the display 594 to form a holographic light field 599 corresponding to one or more objects. The display 594 may include a rearview mirror at its rear to reflect light toward the viewer. The optical diffraction device 598 may be optically transparent. The irradiator 596 may be positioned below the display 594, allowing it to be mounted or housed with other components of the system 590 and positioned below the viewer's line of sight.

As will be discussed in more detail below, Bragg selectivity allows off-axis illumination to diffract from the optical diffraction device 598 toward the display 594, while the light diffracted back from the display 594 can approach the axis and therefore be off-Bragg with respect to the grating of the optical diffraction device 598, and thus can pass through the optical diffraction device 598 almost completely without being diffracted again by the grating of the optical diffraction device 598 and reach the viewer. In some implementations, light from the irradiator 596 can be incident on the optical diffraction device 598 from the side of the display 594 at a large angle of incidence, so that the irradiator 596 does not obstruct the viewer's view and does not penetrate the holographic light field 599. The angle of incidence can be a positive or negative angle with respect to the normal of the display 594. For illustrative purposes, the angle of incidence is presented as a positive angle. For example, the angle of incidence can be in the range of 70 to 90 degrees, e.g., 80 to 90 degrees. In a particular example, the angle of incidence is 84 degrees. The diffracted light from the optical diffraction device 598 can be diffracted at near-perpendicular incidence to the display 594 so that the light can uniformly illuminate the display 594 and minimize power loss due to undesirable reflection, diffraction, and/or scattering within or on the surface of the optical diffraction device 598, causing the light to diffract backward almost perpendicularly to the viewer's eye. In some examples, the diffraction angle from the optical diffraction device 598 to the reflective display 594 can be in the range of -10° (or 10°) to 10° (or 10°), for example, -7° to 7°, or 5° to 7°. In a particular example, the diffraction angle is 6°. In another example, the diffraction angle is 0°.

In some implementations, as illustrated in Figure 5H, the optical diffraction device 598 is positioned in front of the reflective display 594, for example, along the Z-direction toward the viewer. The optical diffraction device 598 may include a field grid structure 598-1 positioned on a substrate 598-2. The back surface of the field grid structure 598-1 faces the front surface of the reflective display 594, and the front surface of the field grid structure 598-1 is attached to the substrate 598-2. Light from the irradiator 596 can be incident, for example, from the side surface of the substrate 598-2, through the substrate 598-2, and onto the front surface of the field grid structure 598-1. For example, the substrate 598-2 may have wedge-shaped sides, as illustrated in further detail in Figure 12C, so that light with a large incident angle can have less reflection loss.

As will be discussed in more detail below, if the diffraction efficiency of a diffraction structure, such as a holographic grating, is less than 100%, light incident at a certain angle of incidence can be diffracted by the diffraction structure into zero-order and first-order diffractencies. The first-order light (or primary light) is diffracted again by the diffraction structure at the angle diffracted toward the display, reconstructing the holographic light field 599. The first-order diffractencies may also be called the first order of diffraction. The zero-order light (or zero-order light, or non-diffracted light, or non-diffracted order) is not diffracted (or non-blinded) by the diffraction structure and is transmitted by the diffraction structure at an angle corresponding to the angle of incidence. The zero-order light can cause undesirable effects, such as ghost images, for example, when the zero-order light is incident directly or subsequently on the reflective display 594 after reflection from a surface within the optical diffraction device 598.

To eliminate undesirable effects, the field grid structure 598-1 can be spaced apart from the display 594. In some implementations, the back surface of the field grid structure 598-1 is spaced apart from the front surface of the display 594 by a gap. The gap can have any preferred distance, for example, 1 mm. The gap can be filled with air or any low refractive index material to satisfy total internal reflection (TIR) at the interface. For example, air has a refractive index (e.g.,) of the back layer of the field grid structure 598-1.
) has a refractive index much smaller than (for example,
) has, and therefore any afterglow of an incident angle (e.g., >70°) is such that the incident angle is the critical angle (e.g.,
in the case of,
When the angle of incidence is greater than the back surface of the field grid structure 598-1, it can be completely internally reflected. That is, the afterglow of the angle of incidence cannot reach the reflective display 594, causing an undesirable effect. In some examples, at least one of the front surface of the reflective display 594 or the back surface of the field grid structure 598-1 is treated with an anti-reflective coating, which can significantly reduce a portion of the holographic light field reflected from the reflective display 594 backward from behind the field grid structure 598-1 toward the reflective display 594, otherwise it could cause further ghosting. In some examples, the back surface of the field grid structure 598-1 can be protected by an additional layer, such as a glass layer.

In some implementations, instead of being separated by a gap, the back surface of the field lattice structure 598-1 can be attached to the front surface of the reflective display 594 using an intermediate layer. The intermediate layer may be an optically transparent adhesive (OCA) layer having a refractive index substantially lower than that of the rear layer of the field lattice structure 598-1, allowing total internal reflection (TIR) to occur, and the remaining zero-order light can be completely reflected back to the optical diffraction structure 598 at the interface between the intermediate layer and the rear layer of the field lattice structure 598-1.

In some implementations, the field grid structure 598-1 and the display 594 can be separated by a gap so that no afterglow can reach the display 594. The gap can be filled with any suitable transparent material, exponentially matched fluid, or OCA. In some implementations, the field grid structure 598-1 can be formed within the cover layer (e.g., cover glass) of the display 594.

In some cases, the active area of the field grid structure 598-1 does not need to be smaller than the area of the entire surface of the reflective display 594 in order to illuminate the entire surface of the reflective display 594 with light diffracted from the active area of the field grid structure 598-1. In some implementations, the field grid structure 598-1 and the reflective display 594 have a rectangular shape with height along the X direction and width along the Y direction. The active area of the field grid structure 598-1 can have a height that is not smaller than the height of the reflective display 594 and a width that is not smaller than the width of the reflective display 594. If there is a substantial gap between the field grid structure 598-1 and the reflective display 594, the field grid structure 598-1 and the substrate 598-2 can be further expanded so that the expanded cone (or frustum of cone) of light from the reflective display 594, for example, the holographic light field 599, can be seen through the front of the optical diffraction device 598 over the entire vertical and horizontal field of view of the holographic light field 599 (around the +Z axis). The substrate 598-2 can be made slightly wider and taller than the field grid structure 598-1.

Since the light is incident on the field grid structure 598-1 at a substantially off-axis angle in a certain dimension, for example, in the Z direction, the light may be narrower by the cosine of the angle of incidence in that dimension. The light from the irradiator 596 can then have a narrow rectangular shape incident on the field grid structure 598-1, which can then expand the light into a larger rectangular shape incident on the reflective display 594. One or more optical components, such as mirrors, prisms, optical slabs, and/or optical fillers, can be placed between and within the irradiator 596, the optical diffraction structure 598, and the reflective display 594 to further expand the light and filter its bandwidth. In some examples, the expanded light may have a beam area slightly smaller than the active area of the reflective display 594 so that the edges and surrounding areas of the illuminated region of the reflective display 594 are not noticeable due to reflection or scattering toward the viewer. In some examples, the extended light may have a beam area slightly larger than the active area of the reflective display 594, so that the edges of the extended light are not uniform, for example, due to diffraction from the masking edge, but the edges of the illuminated area of the reflective display 594 are fully illuminated.

In some implementations, the controller 592 can acquire graphic data containing primitive data for multiple primitives corresponding to objects in three-dimensional space, determine the electromagnetic (EM) field contribution of each of the multiple primitives to each of the multiple display elements of the reflective display 594, generate the sum of the EM field contributions from the multiple primitives to each of the multiple display elements, and generate a control signal for each of the multiple display elements based on the sum of the EM field contributions to the display element.

In some implementations, the irradiator 596 may include one or more light-emitting elements of corresponding colors, such as red, blue, or green lasers (or LEDs), configured to emit light of those colors. The optical diffraction device 598 may be configured to diffract multiple different colors of light at diffraction angles that are substantially identical to each other. Each of these diffraction angles may be substantially identical to a range of 0° to ±10°, for example, 0°, + or -1°, + or -2°, + or -3°, + or -4°, + or -5°, + or -6°, + or -7°, + or -8°, + or -9°, or + or -10°.

In some implementations, the controller 592 is configured to sequentially modulate the display 594 with information associated with multiple colors of light over a series of periods. For example, the information may include a series of color holograms or color images. The controller 592 can control the irradiator 596 to sequentially emit each of the multiple colors of light into the optical diffraction device 598 during each period of the series, so that each of the multiple colors of light is diffracted by the optical diffraction device 598 toward the reflective display 594 and diffracted by the modulated display elements of the reflective display 594 to form the respective color three-dimensional holographic light field 599 corresponding to the object during each period. Depending on the temporal coherence of the visual effect on the viewer's eye, the multiple colors can be combined in the eye to give a full-color appearance. In some cases, the illuminator 596 is switched off between different light-emitting elements during changes in the state of the display image (or holographic reconstruction), such as during black insertion subframes between color subframes, during blanking or retracement periods of the video source, or during LC rise, fall, or DC balancing inversion transitions, or during system warm-up, or when the intended holographic light field is completely black, or during calibration procedures. It is then switched on once a valid image (or holographic reconstruction) has been presented for a certain period. This may also depend on visual persistence to ensure the image (or holographic reconstruction) appears stable and flicker-free.

When a portion of the holographic light field 599 appears in front of the display 594, as illustrated by light field 599-1 in Figure 5H, that portion of the holographic light field 599 is the actual portion of the reconstructed image or holographic reconstruction (also called a real image or real holographic reconstruction). When the viewer sees a point of light in front of the display 594, there is actually light reflected from the display 594 to that point. When a portion of the light field 599 appears to be behind (or inside) the display 594, as illustrated by light field 599-2 in Figure 5H, that portion of the holographic light field 599 is the virtual portion of the reconstructed image or holographic reconstruction (also called a virtual image or virtual holographic reconstruction). When the viewer sees a point of light that appears to be behind or inside the display 594, there is no actual light diffracted from the display 594 to that virtual point; rather, some of the light diffracted from the display 594 appears to originate at that virtual point.

The computer 591 and/or controller 592 can be configured to coordinate the calculation (e.g., by equation) of the information modulated on the display 594 (e.g., a two-dimensional hologram, image, or pattern) to move the reconstructed holographic light field 599 back and forth along a direction perpendicular to the display 594 (e.g., the Z-direction). The calculation may be based on a holographic rendering process, as illustrated, for example, in Figures 2 and 3A-3G. In some cases, the holographic light field 599 may be entirely in front of the display 594. In some cases, the holographic light field 599 may appear to be entirely behind the display 594. In some cases, as illustrated in Figure 5H, the holographic light field may have a portion in front of the display 594, e.g., a real portion 599-1, and another portion that appears to be behind the display, e.g., a virtual portion 599-2. That is, the light field 599 may appear to span the surface of the display 594, which can be called image planning.

The optical diffraction device 598 can be implemented in different configurations. In some implementations, the optical diffraction device 598 includes a holographic grating for a specific color, such as a Bragg grating, as illustrated in Figures 7A, 7B, and 8, and the holographic light field 599 can correspond to a specific color. In some implementations, the optical diffraction device 598 includes multiple holographic gratings for different colors in a single recording layer, as illustrated in Figures 7C, 7D, and 7E.

In some implementations, the optical diffraction device 598 includes multiple holographic gratings for different colors in different recording layers, as illustrated, for example, in Figures 9A–12C. As illustrated in Figure 7F, a grating of a particular color can diffract not only light of that particular color but also light of other colors, which can cause crosstalk between different colors. In some examples, as will be described in more detail below with respect to Figures 9A–10B, the optical diffraction device 598 may include multiple holographic gratings having one or more color-selective polarizers to suppress (e.g., eliminate or minimize) color crosstalk. In some examples, as will be described in more detail below with respect to Figures 11–12C, the optical diffraction device 598 may include multiple holographic gratings having one or more reflective layers for light of different colors incident at each incident angle to suppress color crosstalk and zero-order light. In some examples, the optical diffraction device 598 may include one or more color-selective polarizers, as illustrated in Figures 9A–10B, and multiple holographic gratings having one or more reflective layers, as illustrated in Figures 11–12C, for suppressing color crosstalk and zero-order diffraction. Each color-selective polarizer may be configured for a single color or multiple colors. Each reflective layer may be configured for a single color or multiple colors.

Figure 5I illustrates another system 590A, which includes a reflective display 594A having optical diffraction irradiation using an optical diffraction device 598A. The reflective display 594A may be the same as the reflective display 594 in Figure 5H. Unlike the optical diffraction device 598 of system 590 in Figure 5H, the optical diffraction device 598A of system 590A has a reflective field grating-based structure which may include a reflective field grating structure 598-1A and a substrate 598-2A. The substrate 598-2A may be a glass substrate. The reflective field grating structure 598-1A may include one or more reflective holographic gratings for one or more different colors. The reflective field grating structure 598-1A is positioned, for example, on the front surface of the substrate 598-2A along the Z direction. The irradiator 596 is positioned behind the reflective field grating structure 598-1A and is configured to irradiate the reflective field grating structure 598-1A with light at a large angle of incidence. The light is diffracted backward (along the Z-direction) by the reflective display 594A, which further diffracts the light backward through the optical diffraction device 598A to form a holographic light field 599.

Figure 5J illustrates another system 590B, which includes a transmissive display 594B having optical diffraction irradiation using an optical diffraction device 598B. The transmissive display 594B may be the same as the transmissive display 534 in Figure 5C, 544 in Figure 5D, or 564 in Figure 5E. Similar to the optical diffraction structure 598A in Figure 5I, the optical diffraction structure 598B may be a reflection field grating-based structure that includes a reflection field grating structure 598-1B and a substrate 598-2B. The substrate 598-2B may be a glass substrate. The reflection field grating structure 598-1B may include one or more reflection holographic gratings for one or more different colors. Unlike the optical diffraction structure 598A in Figure 5I, the reflection field grating structure 598-1B in the optical diffraction structure 598B is located on the back surface of the substrate 598-2B. The irradiator 596 is positioned in front of the reflection field grid structure 598-1B and is configured to irradiate the reflection field grid structure 598-1B with light at a large angle of incidence. The light is diffracted backward (along the Z-direction) relative to the transmissive display 594B, which further diffracts the light to form a holographic light field 599.

Figure 5K illustrates another system 590C, which includes a transmissive display 594C having optical diffraction irradiation using an optical diffraction device 598C. The transmissive display 594C may be the same as the transmissive display 594C in Figure 5J. Similar to the optical diffraction structure 598 in Figure 5H, the optical diffraction structure 598C may be a transmissive field lattice-based structure that includes a transmissive field lattice structure 598-1C and a substrate 598-2C. The substrate 598-2C may be a glass substrate. The transmissive field lattice structure 598-1C may include one or more transmissive holographic lattices for one or more different colors. Unlike the optical diffraction structure 598 in Figure 5H, the transmissive field lattice structure 598-1C in the optical diffraction structure 598C is located on the front surface of the substrate 598-2C. The irradiator 596 is located behind the transmissive field lattice structure 598-1C and is configured to irradiate the transmissive field lattice structure 598-1C with light at a large angle of incidence. The light is diffracted forward (along the +Z direction) relative to the transmissive display 594C, which further diffracts the light to form a holographic light field 599.

As discussed above, Figures 5H–5K illustrate different combinations of reflective/transmissive displays and field gratings based on reflective/transmissive optical diffraction devices. In some cases, placing the optical diffraction device behind the display can provide better protection for the photopolymer if the photopolymer is not already protected by its inherent structure or by an additional glass layer. In some cases, the transmissive grating may be mechanically and optically close to the display, and light from the transmissive grating to the display can travel a shorter distance than from the reflective grating, which can reduce alignment, coverage, dispersion, and/or scattering problems. In some cases, the transmissive grating can have larger wavelength tolerances and smaller angular tolerances than the reflective grating. In some cases, the transmissive grating may be less likely to mirror ambient illumination toward a viewer, e.g., an overhead light and an illuminated keyboard. In some cases, with a transmissive display, the viewer can get closer to the display, and the holographic light field can be projected to approach the display. In some cases, for transmissive displays, the glass substrates of transmissive displays can have proven manufacturing capabilities for diagonal dimensions up to >100 inches with nearly seamless tiles for cinema and architectural sizes. In some cases, reflective and transflective displays can embed controllers, such as Maxwell holography circuits, behind the display elements, while transmissive displays can incorporate controllers or circuits behind the inter-pixel (or inter-facel) gaps. In some cases, reflective and transflective displays can allow light to pass through the display elements (e.g., liquid crystal material) twice, and can have twice the refractive index change of transmissive displays that use a single pass through the liquid crystal material. A transflective display can represent a display having an optical layer that reflects transmitted light.

Exemplary Display Implementation As described above, the display in Maxwell holography may be a phase modulation device. The phase element (or display element) of the display can be represented as a fesel. For illustrative purposes only, a liquid crystal on silicon (LCOS) device is considered below to function as a phase modulation device. An LCOS device is a display that uses a liquid crystal (LC) layer on a silicon backplane. An LCOS device can be optimized to achieve the minimum possible fesel pitch, minimum crosstalk between fesels, and/or a large available phase modulation or delay (e.g., at least 2π).

The performance of the LCOS device can be optimized by controlling a list of parameters, including the birefringence (Δn) of the LC mixture, the cell gap (d), the dielectric anisotropy (Δε) of the LC mixture, the rotational viscosity (η) of the LC mixture, and the maximum applied voltage (V) between the silicon backplane and the common electrode on the LC layer.

There can be fundamental trade-offs between parameters of liquid crystal materials and structures. For example, a fundamental boundary parameter is the available phase modulation or delay (Re), which is...
Re=4π・Δn・d/λ(8)
It can be expressed as follows:
In the formula, λ is the wavelength of the input light. For red light with a wavelength of approximately 0.633 μm, if the delay Re must be at least 2π,
Δn ・d ≧ 0.317 μm (9).
The above equation means that for any given wavelength (λ), there exists a direct trade-off between the cell gap (d) and the birefringence (Δn) of the LC mixture.

Another boundary parameter is the switching speed, or switching time (T), which is the time it takes for LC molecules in the liquid crystal (LC) layer to reach the desired orientation after a voltage is applied. For example, in the case of real-time video (approximately 60 Hz) using a three-color continuous color system, a minimum modulation of 180 Hz in the LC layer is involved, which sets an upper limit of 5.6 milliseconds (ms) for the LC switching speed. The switching time (T) is related to several parameters, including the liquid crystal mixture, cell gap, operating temperature, and applied voltage. Firstly, T is proportional to ^d² . As the cell gap d decreases, the switching time decreases according to the square of d. Secondly, the switching time is also related to the dielectric anisotropy (Δε) of the liquid crystal (LC) mixture, with higher dielectric anisotropy resulting in shorter switching times, and lower viscosity (which may be temperature-dependent) also resulting in shorter switching times.

A third boundary parameter can be the fringing field. Due to the high electron mobility of crystalline silicon, LCOS devices can be fabricated with very small facel sizes (e.g., less than 10 μm) and submicron interface gaps. When adjacent facels are operated at different voltages, the LC director near the facel edge is distorted by the lateral components of the fringing field, which significantly degrades the electro-optical performance of the device. In addition, when the facel gap becomes comparable to the incident light wavelength, diffraction effects can cause serious optical loss. To maintain phase noise within acceptable levels, the facel gap may need to be kept below the facel pitch.

In some examples, LCOS devices are designed to have a feszel pitch of 2 μm and a cell gap of approximately 2 μm when fringe field boundary conditions are observed. According to the above equation Δn・d ≥ 0.317 μm, Δn must be greater than or equal to 0.1585, which is achievable using current liquid crystal technology. Once the minimum birefringence for a given feszel pitch is determined, the LC can be optimized for switching speed, for example, by increasing dielectric anisotropy and/or decreasing rotational viscosity.

Non-uniform Fasel Mounting Configurations for Displays In LCOS devices, a circuit chip, e.g., a complementary metal-oxide-semiconductor (CMOS) chip or equivalent, controls the voltage of reflective metal electrodes embedded beneath the chip surface, each controlling one fasel. A common electrode for all fasels is supplied by a transparent conductive layer made of indium tin oxide on the LCOS cover glass. The fasels can be the same size and shape (e.g., square). For example, a chip can have 1024 × 768 (or 4096 × 2160) fasels, each with an independently addressable voltage. As described above, when the fasel gap becomes comparable to the incident light wavelength, diffraction effects may appear due to the periodic structure of the LCOS device, which can cause significant optical loss of diffracted light and a strong periodic structure.

In Maxwell holographic computation, each fesel receives the sum of EM contributions from each primitive and is relatively independent of one another. Therefore, the fesels of an LCOS device in Maxwell holography can be designed to be different from one another. For example, as illustrated in Figure 6A, an LCOS device 600 can be fabricated with several heterogeneous (or irregular) fesels 602. At least two of the fesels 602 have different shapes. The heterogeneous shape of the fesels 602 can significantly reduce or eliminate diffraction anomalies among other effects (e.g., due to the periodic structure of diffracted light), thus improving image quality. While the fesels can have heterogeneous shapes, they can be designed to have a size distribution with an average (e.g., about 3 μm) that satisfies the desired spatial resolution. The silicon backplane can be configured to provide a corresponding circuit (e.g., including metal electrodes) for each fesel according to the shape of the fesels.

In a series of phases in an LCOS device, a first voltage is applied to the word line connecting a series of phases containing the specific phase, and a second voltage is applied to the bit line connecting a series of phases containing the specific phase. Since each phase has resistance and/or capacitance, the operating speed of the LCOS device can be limited by the switching (or rise and fall times) of these voltages.

As described above, in Maxwell holography, the fazels can have different sizes. As illustrated in Figure 6B, the LCOS device 650 is designed to have one or more fazels 654 that are larger in size than the other fazels 652. All fazels can still have a size distribution that satisfies the desired resolution. For example, 99% of the fazels may have a size of 3 μm, and only 1% of the fazels may have a size of 6 μm. The larger size of the fazels 654 allows for the placement of at least one buffer 660 within the fazel 654, in addition to other circuits similar to those in the fazels 652. The buffer 660 is configured to buffer the applied voltage, so that the voltage is applied to only a smaller number of fazels in a row or column of fazels. The buffer 660 may be, for example, an analog circuit made of transistors, or a digital circuit made of several logic gates, or any combination thereof.

For example, as illustrated in Figure 6B, a voltage is applied to word line 651 and another voltage to bit line 653 to select a specific fazel 652*. Fazel 652* is in the same row as a larger fazel 654 containing a buffer 660. The voltage is primarily applied to a first number of fazels in the row and in front of the larger fazel 654, and is interrupted by the buffer 660 in the larger fazel 654. In this manner, the operating speed of the LCOS device 650 can be improved. In larger fazels 654, other circuits may also be placed within the LCOS device 650 to further improve its performance. Fazels 654 and 652 in Figure 6B have a square shape, and fazels can also have different shapes, as long as there are one or more fazels 654 that are larger in size than other fazels 652, as illustrated in Figure 6A.

Exemplary Calibration The unique nature of Maxwell holography in this disclosure enables the protection of calibration techniques that can create a significant competitive advantage in the actual production of high-quality displays. Several calibration techniques can be implemented in combination with Maxwell holographic computation techniques, including:
(i) Using an image sensor or optical field sensor in conjunction with a Dirichlet boundary condition modulator and/or in conjunction with mechanical and software diffraction and non-diffraction calibration techniques,
(ii) Software alignment and software calibration, including individual color calibration and alignment with Dirichlet boundary condition modulators, and (iii) embedding silicon features into the boundary condition modulator that enable the direct incorporation of photodetection (including power and color) and/or temperature measurement into the modulator, which, when combined with Maxwell holography, creates a powerful and unique approach to simplify the manufacturing calibration process.

For illustrative purposes only, three types of calibration are implemented for a phase-based display, such as an LCOS display. Each phase element can be represented as a phase element.

Phase Calibration The amount of phase added to light striking an LCOS phase element (or feszel) can be directly determined by the voltage applied to the LCOS feszel. This is because the birefringent liquid crystal (LC) rotates in the presence of an electric field, thus changing its exponent of refraction, slowing down the light and changing its phase. The changed phase can depend on the electrical properties of the liquid crystal (LC) and the silicon device in which the LC resides. The digital signal transmitted to the LCOS needs to be converted to the correct analog voltage in order to achieve a high-quality holographic image. Phase calibration involves ensuring that the LCOS device is properly converted to the analog signal applied to the LC so that the digital signal produces the maximum possible phase range. This conversion is expected to result in linear behavior; that is, as the voltage changes in a fixed increment, the phase also changes in a fixed increment, regardless of the starting voltage value.

In some cases, the LCOS device allows the user to modify the digital-to-analog converter (DAC) to control the amount of analog voltage output assuming a digital input signal. A digital potentiometer can be applied to each input bit. For example, if there are eight input bits, there may be eight digital potentiometers corresponding to each input bit. The same digital input from the digital potentiometers can be applied to all phases of the LCOS device. Bits set to "1" activate the voltage, and bits set to "0" do not activate the voltage. All voltages from such "1" bits are summed to obtain the final voltage sent to each phase. There may also be a DC voltage applied in all cases so that all "0" bits result in a baseline non-zero voltage. Thus, phase calibration of the LCOS device can be implemented by setting the values of the digital potentiometers of the LCOS device. For example, as described above, the controller can calculate the EM field contribution to each of the display's phases from a list of primitives, generate the sum of the EM field contributions from the primitives to each phase, and generate individual control signals for each phase to modulate the phase of each phase. The same digital input from a digital potentiometer can be applied to adjust each control signal to all phases of the LCOS device, which differs from phase calibration based on each phase. The digital input can be set once over the duration of the LCOS device's operation, for example, to display a hologram.

To determine the optimal set of phase calibration values for a digital input, a genetic algorithm can be applied where many input values lead to a single output value, such as phase range or holographic image contrast. This output value can be reduced to a single number called the fit. The genetic algorithm can be configured to explore different combinations of input values until the most fit output is achieved. In some cases, the algorithm can take two or more of the most fit inputs and combine the numbers of their constituent values to create a new input that has the characteristics of the captured inputs but is different from each of the captured inputs. In some cases, the algorithm can change one of these constituent values to one that is not from any of the taken fitted inputs, which is represented as a "transformation," and can add variety to the available fitted inputs. In some cases, one or more optimal values can be found by using knowledge gained from previous measurements with good results, while trying new values, so that the optimal values are not limited to local maxima.

There are several possible methods for calculating the compatibility output value. One method is to calculate the phase change of light by assuming a set of digital inputs applied to all phasels on the LCOS. In this scheme, the incident light can be polarized. Upon impact with the LCOS, the polarization of the incident light can change depending on the rotation of the LC. The incident light can be diffracted backward through another polarizer set to either the same polarization or a 90-degree different polarization from the original, and then incident on the photodetector. Therefore, as the rotation of the LC changes, the intensity seen from the photodetector can change. Thus, the phase change of light can be perceived indirectly through the intensity fluctuation. Another method for calculating the phase change is to measure the intensity difference of the Maxwell holographic reconstruction from the background. This is most effective in projection displays. To measure the intensity in such an example, it may be necessary to use a computer vision algorithm to identify the Maxwell holographic reconstruction and measure its intensity. Another method for determining the phase change is to microscopically measure or image it in the interference optical geometry.

Alignment Calibration: Light sources and other optical elements may need to be aligned because they may not be properly aligned within the holographic device. Different liquid crystals (LCs) and optical diffracting elements or diffracting optical elements may exhibit different behaviors for different wavelengths of light sources. Furthermore, in particular, LCs, diffracting agents, and light sources can change in the device and over time (aging and burn-in), as well as as a result of changes in the operating environment such as operating temperature, and mechanically induced deformation due to thermal or mechanical stress, giving the same input hologram different characteristics, e.g., object scaling, when displayed in different base colors, or at different times or in different environments. In addition, certain hardware features may apply different optical effects, e.g., lensing effects, to the output light, which may require correction even under these circumstances.

In some implementations, the above problem can be addressed by applying mechanical translation, deformation, and rotation to one or more optical elements. In some implementations, the above problem can be addressed by applying a mathematical transformation to the calculated phase for the display's fasci. The phase is the sum of the respective EM field contributions to the fasci from a list of primitives. The mathematical transformation can be derived from a formula, e.g., a Zernike polynomial, and can be varied by changing the polynomial coefficients or other changing input values. The mathematical transformation can vary not only by color but also by phase. For example, there are Zernike polynomial coefficients corresponding to the amount of gradient applied to the light after diffraction from the display.

To determine these coefficients/input values, a hardware and software setup can be created in which a 2D camera, photometer, optical field camera, and/or other luminometer or colorimeter are directed towards a reflective or diffuse-transmitting surface, either illuminated by an LCOS in the case of a projection display, or directed towards an LCOS in the case of a direct-view display. One or more holographic test patterns and objects can be transmitted to the display and measured by one or more measuring instruments. A 2D camera or a 3D (optical field) camera, or camera array, can use machine vision algorithms to determine what is being displayed and then calculate its fit. For example, if the test pattern is a grid of dots, the fit can be determined by statistical measures such as how close they are, how centered they are in their intended positions, and how much distortion (e.g., scale or pincushion) they exhibit. Different fit values may exist for different performance characteristics. Depending on these values, corrections can be applied, for example, in the form of changing coefficients to a Zernike polynomial, until the fit reaches a predetermined level of satisfaction or passes a visual or task-oriented A/B test. These test patterns can be rendered at different distances to ensure that the alignment is consistent not only for a single 3D point or plane, but also for objects at different distances. Such depth-based calibration can involve an iterative process that modifies the depth of the holographic test pattern or its elements, and the position of reflective or diffusely transmitted surfaces. Previous calibrations can be repeated until they converge to a solution that works at multiple depths. Finally, white dots can be displayed to demonstrate the effectiveness of the calibration.

Color Calibration: In displays, holographics, or other devices, when any two units are rendering the same image, it is crucial that the colors match between the displays and, furthermore, match the colors defined by television (TV) and computer display standards, such as the Rec. 709 standard for high-definition television (HDTV) or the sRGB color space for computer monitors. Different batches of hardware components, such as LEDs and laser diodes, can behave differently for the same input and can output different colors when perceived by the human eye. Therefore, it is important to have a color standard that can calibrate all display units.

In some implementations, objective measurements of color, specified by intensity and chromaticity measurements, can be obtained by measuring color intensity relative to the Commission internationala de l’éclairage (CIE) standard observer curve. Each display is required to reproduce a known sample set of colors and intensities, and then the color output of the device in a selected CIE color space can be objectively defined by measuring the output light using a colorimetric device calibrated to the CIE standard observer curve. Any deviation of the measured values from known good values can be used to adapt the output color on the display back to alignment or fit, which can be implemented using an iterative measure-adapt-measure feedback loop. Once the Maxwell holographic device produces accurate output for a given set of inputs, the final adaptation can be encoded as a lookup table for the illuminator mapping input values to output intensities, and a color matrix transform that converts input colors to output color space values. These calibration tables can be embedded in the device itself to generate reliable, objective output colors. Multiple such tables can be provided for each of the numerous operating temperature ranges. Multiple such tables can also be provided for each of the numerous different regions of the active surface of the LCOS. Calibration values can be interpolated between tables of adjacent temperature ranges and/or adjacent surface regions.

Furthermore, assuming an LCOS device with fine enough features to control diffraction with subwavelength precision, tristimulus irradiation (e.g., a linear mixture of red, green, and blue) may not be necessary. The LCOS device can be irradiated with a single broad-spectrum light source and, in combination with a spatial dithering pattern, can selectively adjust its phase output to produce tristimulus, tetrastimulus, or even N-stimulus output colors that reproduce a more complete spectral output of color than the general tristimulus approximation. Assuming a sufficiently broad-spectrum irradiator, this allows Maxwell holography to produce any reflected color that lies inside the spectral focus of the human visual system or outside the spectral focus of infrared (IR) or ultraviolet (UV) structured light.

Exemplary Holographic Grids Figures 7A–7F illustrate exemplary holographic grid implementations that can be included in an optical diffraction device (or light guide device), for example, the optical diffraction device 598 in Figure 5H, 598A in Figure 5I, 598B in Figure 5J, or 598C in Figure 5K. Figures 7A and 7B illustrate recording and reproducing a holographic grid on a recording medium with a single color. Figures 7C and 7D illustrate recording three different colored holographic grids on a recording medium with three different colored lights (Figure 7C) and reproducing them with a single colored light (Figure 7D). Figures 7E and 7F illustrate reproducing three different colored holographic grids on a recording medium with three different colored lights, and Figure 7F illustrates color crosstalk between diffracted lights of different colors. One of the recording reference light beam, recording object light beam, reproductive reference light beam, or diffracted light beam is a polarized beam that can be s-polarized or p-polarized.

Figure 7A illustrates an example of recording a holographic grid on a recording medium. The recording medium may be a photosensitive material, such as a photosensitive polymer or photopolymer, silver halide, or any other suitable material. The recording medium can be placed on a substrate, such as a glass substrate. The substrate may be transparent or opaque during recording. In some mounting configurations, the photosensitive material can be bonded to a carrier film, such as a TAC (triacetate cellulose) film. The photosensitive material with a carrier film, together with the photosensitive material between the carrier film and the substrate, can be laminated on the substrate.

In transmission holography, a recording reference beam and a recording object beam are incident on the same region of the recording medium from the same side, at a recording reference angle _θr and a recording object angle _θo , respectively. Each of the reference beam and object beam can start in air, pass through the photosensitive material, then pass through the substrate and exit into air. The recording reference beam and the recording object beam have the same color, e.g., green, and the same polarization state, e.g., s-polarized. Both beams can be generated from a laser source with high spatial and temporal coherence such that the beams strongly interfere to form an upright pattern of overlapping beams. Within the recording medium, the pattern is expressed by the formula,
θ _t =(θ _o +θ _r )/2(10)
At a fringe inclination angle _θt that satisfies the conditions, a fringe pattern including multiple parallel interference surfaces, such as a grid, is recorded, as illustrated by the inclined solid line in Figure 7A.
In the formula, _θt represents the fringe tilt angle of the recording medium during recording, _θo represents the object angle of the recording medium during recording, and _θr represents the reference angle of the recording medium during recording.

The fringe interval (or fringe duration) d on the surface of the recording medium is:
d=λ _record /(n sinθ _record ) (11)
It can be expressed as follows:
In the formula, λ _record represents the recording wavelength (in vacuum), n represents the refractive index of the medium surrounding the lattice (e.g., air with n = 1.0), θ _record represents the beam-to-beam angle during recording and is identical to |θ _o - _{θ r} |, where θ _o represents the object incidence angle on the surface of the recording medium during recording, and θ _r represents the reference incidence angle on the surface of the recording medium during recording. In some cases, the fringe spacing d has a size similar to the wavelength of the recording light, e.g., 0.5 μm. Thus, the fringe pattern can have a frequency f = 1/d, e.g., about 2,000 fringes/mm. The thickness D of the recording medium can be more than an order of magnitude larger than the wavelength of the recording light. In some examples, the thickness D of the recording medium is about 30 times the wavelength, e.g., about 16.0 ± 2.0 μm. The carrier film can have a greater thickness than the recording medium, e.g., 60 μm. The substrate can have a thickness several orders of magnitude greater than that of the recording medium, for example, about 1.0 mm.

After the fringe pattern or grid is recorded on the recording medium, the fringe pattern can be fixed to the recording medium as an example of a photopolymer by exposure to, for example, dense blue light or ultraviolet (UV) light, which can freeze the fringes in place and enhance the refractive index difference of the fringes. The recording medium can shrink during fixation. The recording medium can be selected to have a low shrinkage rate during fixation, e.g., less than 2%, or such shrinkage can be compensated for.

As each beam passes through the interface between materials with different refractive indices, some portion of the beam is reflected according to Fresnel's law, yielding a percentage of the power reflected at each transition. Reflection is polarization-dependent. For smaller angles of incidence, e.g., 30°, Fresnel reflection may be weaker. For larger angles of incidence (e.g., 80°), and for s-polarized light, Fresnel reflection may be stronger. When the angle of incidence reaches or exceeds the critical angle, total internal reflection (TIR) occurs, meaning the reflectivity is 100%. For example, from the transition from glass (n=1.5) to air (n=1.0), the critical angle is approximately 41.8°. Because refractive index is polarization-dependent and weakly wavelength-dependent, reflected power at large angles of incidence may be weakly wavelength-dependent and strongly polarization-dependent.

Figure 7B illustrates an example of diffracting the reconstructed reference beam using the grating in Figure 7A. In transmission holography, the substrate is transparent during reconstruction. The substrate can also be an optically transparent plastic such as TAC or some other low birefringence plastic. If the recorded grating in the recording medium is thin compared to the wavelength of the reconstructed reference beam, for example, if the thickness of the recording medium is less than an order of magnitude greater than the reconstructed wavelength, the diffraction angle of the grating is:
m λ _replay = n d (sin θ _in - sin θ _out ) (12)
It can be described by lattice equations as follows:
In the formula, m represents the diffraction order (integer), n represents the refractive index of the medium surrounding the lattice, d represents the fringe spacing on the surface of the recording medium, θ _in represents the angle of incidence from the surrounding medium to the lattice, θ _out represents the m-th order output angle from the lattice to the surrounding medium, and λ _replace represents the regeneration wavelength in a vacuum.

When the recorded grating is relatively thick, for example, when the thickness of the recording medium is more than an order of magnitude (e.g., 30 times) greater than the reconstructed wavelength, the grating can be called a volume grating or Bragg grating. In the case of a volume grating, Bragg selectivity can strongly increase diffraction efficiency at the Bragg angle. The Bragg angle can be determined based on numerical methods, e.g., exact coupled wave solutions, and/or experiment and iteration. At off-Bragg angles, diffraction efficiency can be substantially reduced.

The Bragg condition can be satisfied when the angle of incidence to the fringe plane is equal to the angle of diffraction from the fringe plane in the medium containing the fringe plane. Then, the lattice equation (12) is Bragg's equation,
m λ _replay =2 n _replay Λ _replay sin(θ _m −θ _t ) (13)
It could become,
In the formula, m represents the diffraction order (or Bragg order), n _replace represents the refractive index in the medium, Λ _replace represents the fringe spacing in the recording medium, θ _m represents the m-th Bragg angle in the recording medium, θ _t represents the fringe inclination in the recording medium, and Λ _replace may be the same as d cosθ _t .

The Bragg condition can be automatically satisfied for a volume grating recorded and reconstructed at the same angle and wavelength (assuming no shrinkage during processing). For example, as illustrated in Figure 7B, if a volume grating is recorded and reconstructed at the same wavelength (e.g., green) and reference angle (e.g., _θr ), the grating can diffract the first-order reconstructed beam at the angle of the recorded object beam. A small portion of the incident light beam can pass through the grating as an unbent or undiffracted zero-order light beam. When the zero-order light beam reaches a display such as a reflective LCOS device, the light beam can cause undesirable effects, such as ghost images.

If the reference angle for reconstruction remains unchanged, but the reference wavelength for reconstruction is changed, the diffraction efficiency η of the Bragg grating in the recording medium will be:
η∝2D _replay sinθ _Bragg ² δλ cosθ _{tilt. replay} /(λ _Bragg ² cosθ _Bragg ) (14)
It can be expressed as follows:
In the equation, η represents the diffraction efficiency, D- _replay represents the thickness of the recording medium during playback (after shrinkage), θ- _Bragg represents the playback reference angle at Bragg for the intended playback wavelength λ- _Bragg (after shrinkage), and δλ represents the error in the playback wavelength, i.e., δλ = |λ-replay - λ-Bragg|, where θ- _tilt-replay represents the fringe tilt of the recording medium during playback (after shrinkage). All λ values are in vacuum.

Figure 7C illustrates an example of recording different colored grids on a recording medium using light of different colors. As illustrated, three fringe patterns (or grids) can be recorded on a single recording medium, for example, sequentially or simultaneously. The fringe patterns correspond to regenerated colors (e.g., red, green, or blue) and can be recorded at different wavelengths. The recording reference beam and the recording object beam have the same polarization state. Each beam can be s-polarized. The recording reference beam for each color can be incident on a single recording medium at the same reference beam angle _θr (e.g., +30°). The recording object beam for each color can be incident on a single recording medium at the same object beam angle _θo (e.g., -20°).

Since _θt is independent of wavelength, the fringe plane tilt _θt of each grating during recording can be the same, for example, _θt = ( _θo + _θr )/2. The fringe spacing d perpendicular to the fringe plane during recording can be different for each grating because d depends on wavelength. In some examples, as illustrated in Figure 7C, the fringe spacing corresponds to exemplary wavelengths of 640 nm:520 nm:460 nm,
This is the proportion.

Figure 7D illustrates an example of recording different colored grids on a recording medium using light of the same color. Similar to Figure 7C, three fringe patterns are recorded on a single photopolymer, with one fringe pattern recorded for each regeneration color. Unlike Figure 7C, the three fringe patterns in Figure 7D can be recorded using the same wavelength, e.g., green light. To achieve this, the recording object beam for each regeneration color can be incident on the single recording medium at different object beam angles, and the recording reference beam for each regeneration color can be incident on the single recording photopolymer at different reference beam angles. The fringe slope and fringe spacing for the regeneration colors in Figure 7D can be matched to the fringe slope and fringe spacing for the same regeneration colors in Figure 7C.

Figure 7E illustrates an example of diffracting different colored regenerated reference beams using different colored gratings. The gratings can be recorded as illustrated in Figures 7C or 7D. Similar to Figure 7B, for regenerated colors, if the recording wavelength is the same as the regenerated wavelength and the regenerated reference angle is the first Bragg angle of the regenerated color grating, the grating diffracts the primary regenerated reference beam at the same diffraction angle as the recording object angle and transmits the zero-order regenerated reference beam at the regenerated reference angle. Due to Bragg selectivity, the power of the primary regenerated reference beam can be substantially greater than the power of the zero-order regenerated reference beam. The three regenerated reference beams can have the same incident angle, e.g., 30°, and the primary diffracted beam can have the same diffraction angle, e.g., 20°.

The reference angles for the reproduction of each color are neither equal to each other nor can they be equal to the angles of the colors used during recording. For example, in the case of green, the grating can be recorded at 532 nm using a high-power, high-coherence green laser, such as a frequency-doubling diode-pumped YaG laser, and then reproduced at 520 ± 10 nm using a green laser diode. In some cases, a green laser with a wavelength of 532 nm can be used to record the fringe pattern necessary for reproduction using an inexpensive red laser diode of 640 ± 10 nm. In the case of blue, the grating can be recorded at 442 nm using a HeCd laser and reproduced using a blue laser diode of 460 ± 2 nm.

Figure 7F illustrates an example of crosstalk between diffracted beams of different colors. Despite Bragg selectivity, each color can also slightly diffract the gratings recorded for each other, which can cause crosstalk between these colors. Compared to Figure 7E, which provides only first-order diffraction for the corresponding color, Figure 7F provides first-order diffraction for each color from each grating.

For example, as illustrated in Figure 7F, red, green, and blue grids are recorded, respectively. When red light is incident on the red grid at the same reference angle of 30°, the diffraction angle of the primary red light is 20°. However, when red light is incident on the green grid at the same reference angle of 30°, the diffraction angle of the primary red light is 32°, and when red light is incident on the blue grid at the same reference angle of 30°, the diffraction angle of the primary red light is 42°. Therefore, diffracted light can exist at unintended angles, causing color crosstalk. Similarly, when green light is incident on the green grid at the same reference angle of 30°, the diffraction angle of the primary green light is 20°. However, when green light is incident on the red grid at the same reference angle of 30°, the diffraction angle of the primary green light is 11°, and when green light is incident on the blue grid at the same reference angle of 30°, the diffraction angle of the primary green light is 27°. Therefore, diffracted light can exist at unintended angles, resulting in color crosstalk. Similarly, when blue light is incident on a blue grating at a reference angle of 30°, the diffraction angle of the primary blue light is 20°. However, when blue light is incident on a red grating at the same reference angle of 30°, the diffraction angle of the primary blue light is 6°, and when blue light is incident on a green grating at the same reference angle of 30°, the diffraction angle of the primary blue light is 14°. Therefore, diffracted light can exist at unintended angles, resulting in color crosstalk. Thus, when light of a single color, for example, green light, is incident on three gratings of a recording medium, the three gratings diffract the single color light, resulting in a first diffracted green light at a diffraction angle of 20°, a second diffracted green light at a diffraction angle of 27°, and a third diffracted green light at a diffraction angle of 11°. The two unintended angles of each diffracted color of light can produce undesirable effects.

In some cases, instead of recording three different grids of three different colors on a single recording layer, three different grids can be stored on three separate recording layers stacked together. As shown in Figure 7F, color crosstalk can occur if three different colored lights are incident on any one of the grids at the same angle of incidence. The embodiments of this disclosure provide methods and devices for suppressing color crosstalk in multiple grid stacks, as illustrated in further detail in Figures 9A–12C.

Figure 8 illustrates an example of recording a holographic grating with a large reference angle on a recording medium. Using a large regeneration reference beam angle allows for a thin regeneration system. Furthermore, the regeneration output beam, i.e., the primary diffraction angle, can be perpendicular to the display. Therefore, the recording object beam can be close to perpendicular incidence, as illustrated in Figure 8.

In Bragg diffraction, Fresnel reflection of both p-polarized and s-polarized light is low in each fringe plane, but at an incidence angle of 45°, s-polarized light can be reflected orders of magnitude more strongly than p-polarized light. Therefore, when the incidence angle of the reconstructed reference beam to the fringe in the recording medium is close to 45°, the Bragg resonance from the fringe can be very polarization sensitive and strongly prefer s-polarized light. The recording object beam can be incident nearly perpendicular to the recording medium so that the reconstructed object beam or diffracted reconstructed beam can be incident nearly perpendicularly onto the display. Since the fringe inclination in the recording medium is the average value of the recording object and reference angle in the medium, a recording reference angle approaching 90° in the recording medium can be used to achieve an incidence angle to the fringe close to 45° during reconstruction, and therefore high polarization selectivity. The inter-beam angle between the recording object beam and the recording reference beam can be close to 90°. For example, the beam-to-beam angle is 84°, as illustrated in Figure 8; the fringe inclination of the fringe plane within the recording beam is 42°; and the incidence angle of the regenerated reference beam relative to the fringe plane is 48°. This corresponds to a polarization sensitivity of approximately 90:1.

In some cases, to achieve a re-output (or primary) diffraction angle of 0°, the recording object beam may be close to 0°, rather than identical to 0°. This can be achieved by taking into account the contraction of the recording medium during processing and the slight wavelength difference between the recording and re-recording wavelengths. For example, the recording object angle may be in the range of -10° to 10°, e.g., -7° to 7°, or 5° to 7°. In some examples, the recording object angle is 0°. In some examples, the recording object angle is 6°.

In some implementations, during recording, a prism is applied so that each recording beam enters the prism through its prism surface to achieve a sufficiently large inter-beam angle, for example, close to 90°. Since the angle of incidence to the prism is close to the normal of that surface, both refraction and Fresnel losses become negligible. The prism can be index-matched to the cover film or substrate of the recording medium at the interface, so that refractive index mismatch is negligible at the interface, and refraction and Fresnel losses are also negligible at the interface.

Exemplary Optical Diffraction Devices Figures 9A–12C show exemplary implementations of optical diffraction devices. Any one of the devices may correspond, for example, to optical diffraction device 598 in Figure 5H or 598C in Figure 5K. Optical diffraction devices are configured to diffract light individually in multiple colors in order to suppress (e.g., reduce or eliminate) color crosstalk between diffracted light and/or to suppress zero-order non-diffracted light. Figures 9A–10B show exemplary optical diffraction devices including a color-selective polarizer. A color-selective polarizer can selectively change the polarization of a selected color, so that light of a single color may have s-polarization to achieve high diffraction efficiency in the first order, while light of other colors may have p-polarization, and therefore lower diffraction efficiency in the first order. Figures 11–12C show exemplary optical diffraction devices including a reflective layer. A reflective layer can selectively and completely reflect zero-order single-color light while transmitting light of other colors.

Optical Diffraction Device with Color-Selective Polarizer Figure 9A illustrates an exemplary optical diffraction device 900 including two color holographic gratings and corresponding color-selective polarizers, and Figure 9B illustrates an example 950 in which the optical diffraction device 900 of Figure 9A diffracts two colors of light. For illustrative purposes, the device 900 is configured for green light and blue light.

The optical diffraction device 900 includes a first optical diffraction component 910 having a first diffraction grating (B grating) 912 for blue light, and a second optical diffraction component 920 having a second diffraction grating (G grating) 922 for green light. Each diffraction grating may be between a carrier film, e.g., a TAC film, and a substrate, e.g., a glass substrate. The carrier film may be behind the diffraction grating, and the substrate may be in front of the diffraction grating along the Z direction, or vice versa. As illustrated in Figure 9A, the first optical diffraction component 910 includes a substrate 914 and a carrier film 916 on both sides of the B grating 912, and the second optical diffraction component 920 includes a substrate 924 and a carrier film 926 on both sides of the G grating 922. The optical diffraction device 900 may include a grating substrate 902 on which the first optical diffraction component 910 and the second optical diffraction component 920 are laminated. The anti-reflective (AR) coating 901 can be attached to the surface of the grid substrate 902, or applied to its surface to reduce reflection.

The optical diffraction device 900 also includes one or more layers of optically transparent index-matching adhesive (OCA), UV-curable or thermosetting optical adhesive, optical contact, or index-matching fluid to attach or bond adjacent layers or components, such as the field lattice substrate 902 and BY filter 904, the BY filter 904 and the first diffraction component 910 (or substrate 914), the first diffraction component 910 (or carrier film 916) and the GM filter 906, and/or the GM filter 906 and the second diffraction component 920 (or substrate 924). The order of the carrier film 914 or 924, the substrate 916 or 926, and the OCA layer is determined based on their refractive indices at the wavelength of the regenerated light to reduce refractive index mismatch at the interface and, therefore, reduce Fresnel reflection at the interface.

Each of the first and second diffraction gratings may independently be a holographic grating (e.g., a volume grating or Bragg grating) recorded and fixed (e.g., cured) on a recording medium, such as a photosensitive polymer. The thickness of the recording medium may be more than an order of magnitude greater than the recording wavelength, for example, about 30 times. Similar to the examples illustrated in Figure 7A or Figure 8, a recording reference beam incident on the recording medium at a recording reference angle and a recording object beam incident at a recording object angle can interfere with the recording medium to form a diffraction grating. Then, similar to the examples illustrated in Figure 7B, the regenerated reference beam can be diffracted by the recorded diffraction grating in the first and zero order. The recording beam and the regenerated beam may have the same s-polarization state. The regeneration wavelength of the regenerated beam may be substantially identical to the recording wavelength of the recording beam.

In some examples, the regeneration incidence angle can be substantially identical to the recording reference angle (or Bragg angle), satisfying the Bragg condition. The primary light (or primary beam) is diffracted at a diffraction angle substantially close to the recording object angle, while the zeroth-order light (or zeroth-order beam) is transmitted undiffracted at the regeneration incidence angle. For Bragg selectivity, the power of the primary light can be substantially higher than the power of the zeroth-order light. The power of the zeroth-order light (e.g., afterglow or depletion light) depends on the diffraction efficiency of the diffraction grating. Higher diffraction efficiency results in lower zeroth-order light power. In some examples, the recording reference angle, recording object angle, regeneration incidence angle, recording wavelength, and regeneration wavelength can be configured such that the regeneration output angle (or angle diffracted by the primary beam) is substantially close to 0° or perpendicular to the grating. The diffraction angle can be in the range of -10° to 10°, e.g., -7° to 7°, 0° to 10°, or 5° to 7°. In certain examples, the diffraction angle is 6°.

Furthermore, due to polarization sensitivity, the diffraction efficiency of s-polarized light of a first color (e.g., blue) incident at the regeneration reference angle and diffracted first-order at the diffraction angle can be substantially higher than the diffraction efficiency of p-polarized light of the same color incident at the regeneration reference angle and diffracted first-order at the diffraction angle. As illustrated in Figure 7F, light of a second color (e.g., green) incident at the same regeneration incidence angle as light of the first color is diffracted at a different diffraction angle than that of the first color. Therefore, due to both Bragg sensitivity and polarization sensitivity, the diffraction efficiency of the first color incident in s-polarized state at the regeneration incidence angle can be substantially higher than the diffraction efficiency of light of the second color incident in p-polarized state at the same or different regeneration incidence angles.

The optical diffraction device 900 can be configured to suppress crosstalk between the blue and green diffracted light beams. For example, if the B grating 912 is positioned in front of the G grating 922 within the device 900 along the Z direction, the light is incident on the B grating 912 before it is incident on the G grating 922. The optical diffraction device 900 can be configured so that the blue light is incident on the B grating 912 in an s-polarized state, the green light is incident on the B grating 912 in a p-polarized state, and the green light is incident on the G grating 922 in an s-polarized state. In some cases, the optical diffraction device 900 can also be configured so that the remaining blue light is incident on the G grating 922 in a p-polarized state.

In some implementations, as shown in Figures 9A and 9B, the optical diffraction device 900 may include a color-selective polarizer 906 (also known as a color-selective retarder or filter) between the first diffraction grating 912 and the second diffraction grating 922 (or between the first diffraction component 910 and the second diffraction component 920). The color-selective polarizer 906 may include a GM filter configured to rotate the polarization state of green light by 90 degrees, for example, from a p-polarized state to an s-polarized state, without rotating the polarization state of blue light.

In some implementations, as shown in Figures 9A and 9B, the optical diffraction device 900 may include another color-selective polarizer 904 positioned in front of the first diffraction grating 912 and the second diffraction grating 922 along the Z direction. The color-selective polarizer 904 may include a BY filter configured to rotate the polarization state of blue light by 90 degrees from a p-polarization state to an s-polarization state without rotating the polarization state of green light.

As shown in Figures 9A and 9B, both blue light 952 and green light 954 can be incident into the optical diffraction device 900 simultaneously or sequentially in a p-polarized state. The two colors of light can have the same incident angle θ°. When the blue light 952 and green light 954 are first incident on the BY filter 904, the color-selective polarizer 904 rotates the p-polarized state of the blue light to an s-polarized state without rotating the polarization state of the green light, so that the blue light is incident on the B grating 912 in an s-polarized state and the green light is incident on the B grating 912 in a p-polarized state. The B grating 912 diffracts the blue light in the s-polarized state to first-order blue light 952' at a certain diffraction angle with a first diffraction efficiency, and transmits zero-order blue light 952'' at the incident angle. For polarization sensitivity and Bragg sensitivity, the B grating 912 diffracts the green light 954 in the p-diffracted state with a diffraction efficiency substantially lower than the first diffraction efficiency, and most of the green light 954 in the p-diffracted state is transmitted through the B grating 912. The color-selective polarizer 906 rotates the p-polarized state of the green light to the s-polarized state without rotating the s-polarized state of the blue light, so that the G grating 922 diffracts the green light 954' in the first-order order at a certain diffraction angle with a second diffraction efficiency, and transmits the green light 954' in the zero-order order at the angle of incidence. Therefore, the diffracted blue light 952' and green light 954' exit the optical diffraction device 900 in the same s-polarized state and at the same diffraction angle, for example, -10° to 10°, or -7° to 7°, or substantially close to 0° to the device 900, or perpendicular to the device 900.

As shown in Figure 5H, the optical diffraction device 900 can be positioned along the Z-direction in front of the cover glass 930 of the display, for example, the display 594 in Figure 5H. As discussed above in Figure 5H, the optical diffraction device 900 can be attached to the cover glass 930 with an OCA layer or exponentially matched oil, or separated by a gap such as an air gap. The diffracted blue light 952' and green light 954' can be incident on the display with the same s-polarization state and the same angle of incidence (e.g., substantially perpendicular incidence). The display can diffract the blue light 952' and green light 954' backward into and through the optical diffraction device 900. The blue and green light diffracted from the display cannot be further significantly diffracted by the optical diffraction device 950 because it is incident on the diffraction gratings 912 and 922 at a far off-Bragg angle.

The display 594 can be illuminated by polarizing light in the direction of the display's alignment layer or perpendicular to the display's alignment layer. Since the display can rotate in its own plane between horizontal and vertical orientation, the required polarization depends on the orientation of the display. In some implementations, the display can be illuminated with p-polarization. Blue and green light diffracted from the optical diffraction device 900 can be incident on the display in the same p-polarization state. The optical diffraction device 900 includes an additional color-selective polarizer after the G-grottery 922, which can rotate the s-polarization state of the blue light 952' and green light 954' to the p-polarization state.

In some implementations, blue light is incident on the optical diffraction device 900 in an s-polarized state, green light in a p-polarized state, and the optical diffraction device 900 may not include a BY filter 904 in front of the B grating 912 for rotating the polarization state of the blue light.

In some implementations, as will be discussed in more detail in Figures 11-12C, zero-order non-diffracted (or transmitted) blue light and/or zero-order non-diffracted (or transmitted) green light can be completely reflected internally by one or more reflective layers arranged within the optical diffraction device 900.

Figure 10A illustrates an exemplary optical diffraction device 1000, which includes three color holographic gratings and corresponding color-selective polarizers for individually diffracting three colors of light. Figure 10B illustrates an example of diffracting three colors of light using the optical device of Figure 10A. Compared to Figures 9A and 9B, the optical diffraction device 1000 includes additional diffraction components for additional colors and different color-selective polarizers for the three colors. For illustrative purposes, the device 1000 is configured for blue light, red light, and green light.

As illustrated in Figure 10A, the optical diffraction device 1000 can be positioned in front of the cover glass 1050 of a display, for example, the display 594 in Figure 5H, along the Z-direction. The optical diffraction device 1000 includes a first diffraction component 1010, a second diffraction component 1020, and a third diffraction component 1030, which can be sequentially stacked on a field grating substrate 1002 along the Z-direction. An AR film 1001 can be applied or coated on the front surface of the field grating substrate 1002 to reduce light reflection. Each of the first diffraction component 1010, the second diffraction component 1020, and the third diffraction component 1030 may include their respective substrates 1014, 1024, 1034, their respective diffraction gratings 1012, 1022, 1032, and their respective carrier films 1016, 1026, 1036. Each diffraction grating 1012, 1022, and 1032 is located between each substrate 1014, 1024, and 1034 and each carrier film 1016, 1026, and 1036. In some cases, each substrate 1014, 1024, and 1034 is located in front of each carrier film 1016, 1026, and 1036 along the Z-direction. In some cases, each carrier film 1016, 1026, and 1036 is located in front of each substrate 1014, 1024, and 1034 along the Z-direction.

Each of the first diffraction gratings 1012, the second diffraction grating 1022, and the third diffraction grating 1032 can be configured to diffract monochromatic light in an s-polarized state incident at a certain angle of incidence at a diffraction angle substantially higher, for example, by more than one order of magnitude, two orders of magnitude, or three orders of magnitude, than the diffraction efficiency at which the diffraction grating diffracts light of another color in a p-polarized state incident at the same or a different angle of incidence. Each of the first diffraction gratings 1012, the second diffraction grating 1022, and the third diffraction grating 1032 may be a holographic grating, such as a volume grating or a Bragg grating. Each of the first diffraction gratings 1012, the second diffraction grating 1022, and the third diffraction grating 1032 can be independently recorded and fixed on a recording medium, such as a photosensitive polymer or photopolymer.

The optical diffraction device 1000 may include multiple color-selective polarizers for three colors of light. In some implementations, the BY filter 1004 is located between the field grating substrate 1002 and the first diffraction grating 1012 of the first diffraction component 1010, and is configured to rotate the polarization state of blue light without rotating the polarization states of red and green light, respectively. The MG filter 1006 is located between the first diffraction grating 1012 and the second diffraction grating 1022 (or between the first diffraction component 1010 and the second diffraction component 1020), and is configured to rotate the polarization states of blue and red light, respectively, without rotating the polarization state of green light. The YB filter 1008 is located between the second diffraction grating 1022 and the third diffraction grating 1032 (or between the second diffraction element 1020 and the third diffraction element 1030), and is configured to rotate the polarization states of red and green light without rotating the polarization state of blue light. The MG filter 1040 is located after the third diffraction grating 1032 (or the third diffraction element 1030), and is configured to rotate the polarization states of red and blue light without rotating the polarization state of green light.

In some implementations, a color-selective polarizer is composed of two or more sub-polarizers. The sub-polarizers can be arranged in any desired order. For example, the YB filter 1008 can be composed of an RC filter 1008-1 and a GM filter 1008-2. The RC filter 1008-1 can be placed before the GM filter 1008-2, or vice versa. The RC filter 1008-1 is configured to rotate the polarization state of red light without rotating the polarization states of the respective green and blue light, and the GM filter 1008-2 is configured to rotate the polarization state of green light without rotating the polarization states of the respective red and blue light.

Adjacent layers or components within the optical diffraction device 1000 can be joined together using one or more intermediate layers selected from OCA, UV-curable or thermosetting optical adhesives, optical contacts, or exponentially matching fluids. As considered in Figure 5H, the optical diffraction device 1000 can be attached to the display cover glass 1050 through the intermediate layer, or separated by a gap, such as an air gap.

The optical diffraction device 1000 is configured to diffract three colors of light (red, green, and blue) toward a display with the same polarization state (e.g., s or p) and the same diffraction angle (e.g., substantially perpendicular incidence). The three colors of light can be input to the optical diffraction device 1000 at the same incidence angle θ°, for example, substantially identical to the Bragg angle. In some cases, the three colors of light can be incident at different angles to match the Bragg angle of each color grating. The three colors of light can be in a beam large enough to illuminate the entire area of the grating. The three colors of light can be input to the optical diffraction device 1000 with the same polarization state (e.g., s or p). In some cases, light of one color is incident from the opposite side (e.g., at -θ°) or from the Y direction. Each color grating can be rotated to match the direction of the corresponding color reproduction reference light. The corresponding color-selective polarizer may be independent of the rotation of the color gratings.

Figure 10B illustrates an example 1060 in which three colors of light (blue, red, and green) are diffracted by the optical diffraction device 1000 shown in Figure 10A. The three colors of light are incident on the optical diffraction device 1000 at the same incident angle θ° and with the same p-polarization state.

As shown in Figure 10B, the BY filter 1004 rotates the p-polarized state of blue light to an s-polarized state without rotating the p-polarized states of the red and green light. The B grating 1012 diffracts the blue light in the s-polarized state first order at the diffraction angle and zero order at the incident angle. Green and red light incident in the p-polarized state at the incident angle passes through the B grating 1012.

The MG filter 1006 rotates the s-polarized state of blue light to a p-polarized state, and the p-polarized state of red light to an s-polarized state, without rotating the p-polarized state of green light. The R grating 1022 diffracts the red light in the s-polarized state first order at the diffraction angle and zero order at the incident angle. The remaining zero-order blue light and the green light incident in the p-polarized state at the incident angle are transmitted through the R grating 1022.

In the YB filter 1008, the RC filter 1008-1 rotates the s-polarized state of red light to a p-polarized state without rotating the p-polarized states of the green and blue light. The GM filter 1008-2 of the YB filter 1008 rotates the p-polarized state of green light to an s-polarized state without rotating the p-polarized states of the red and blue light. The remaining zero-order blue light, the remaining zero-order red light, and green light pass through the RC filter 1008-1 and the GM filter 1008-2.

The G-grottery 1032 diffracts green light in the s-polarized state in a first-order order at the diffraction angle and a zero-order order at the incident angle. The remaining blue light, and the remaining red light incident in a p-polarized state at the incident angle, are transmitted through the G-grottery 1032.

The MG filter 1040 rotates the p-polarized states of red and blue light to s-polarized states without rotating the s-polarized state of the green light. The diffracted blue, red, and green light, in their s-polarized states at the same diffraction angle, propagates from the optical diffraction device 1000. The remaining blue light, remaining red light, and zero-order remaining green light are also in the s-polarized state and pass through the MG filter 1040 at the angle of incidence.

In some implementations, the optical diffraction device 1000 can be larger than the display. The remaining zero-order blue, red, and green light can propagate from the device 1000 into the air at a large angle. In some implementations, as will be discussed in more detail below in Figures 11-12C, the optical diffraction device 1000 may include one or more reflective layers between or after the diffraction grating for total internal reflection of the corresponding zero-order color light.

Exemplary Optical Diffraction Devices with Reflective Layers Figures 11–12C show exemplary optical diffraction devices including reflective layers. The reflective layers can selectively and completely reflect light of a single color of the zeroth order while transmitting light of other colors. Each optical diffraction device includes multiple gratings, each for light of a different color. Light of each color can be incident on the corresponding grating at different regeneration reference angles, and thus each color of light of the zeroth order, which is not diffracted (or transmitted) by the grating, undergoes total internal reflection (TIR) from the interface, following a grating that diffracts light of the primary color at the same diffraction angle (e.g., substantially perpendicular), prior to any subsequent gratings in the device (if any). Light of other colors can be transmitted through the grating at the corresponding regeneration reference angles.

Figure 11 illustrates an exemplary optical diffraction device 1100, which includes two color diffraction gratings and corresponding reflective layers for diffracting two colors of light separately. For illustrative purposes, the device 1100 is configured for green and blue light.

The optical diffraction device 1100 includes a first diffraction component 1110 having a first diffraction grating 1112 for blue light, and a second diffraction component 1120 having a second diffraction grating 1122 for green light. Each of the first and second diffraction gratings 1112 and 1122 may be a holographic grating, such as a Bragg grating or a volume grating. Each of the first and second diffraction gratings 1112 and 1122 can independently record and fix data on a recording medium, such as a photosensitive material like a photopolymer.

The first diffraction component 1110 and the second diffraction component 1120 can be stacked together on a field lattice substrate 1102 along a certain direction, for example, the Z direction. The field lattice substrate 1102 may be an optically transparent substrate, such as a glass substrate. The optical diffraction device 1100 may be located in front of a display such as an LCOS, for example, the display 594 in Figure 5H. For example, the optical diffraction device 1100 may be placed on the cover glass 1130 of the display through an intermediate layer, or it may be separated by a gap, such as an air gap.

Similar to the first diffraction element 910 and the second diffraction element 920 in Figures 9A and 9B, each of the first diffraction element 1110 and the second diffraction element 1120 may include their respective substrates 1114 and 1124 and their respective carrier films 1116 and 1126 on either side of their respective diffraction gratings 1112 and 1122. Each diffraction grating 1112 and 1122 is located between their respective substrates 1114 and 1124 and their respective carrier films 1116 and 1126. The respective substrates 1114 and 1124 and their respective carrier films 1116 and 1126 may be arranged in a sequence to reduce refractive index mismatch, and therefore undesirable Fresnel reflection. Each substrate 1114 and 1124 may be a glass substrate having the same or close refractive index as the grating substrate 1102. Each carrier film 1116 and 1126 may be a TAC film. The TAC film can have a lower refractive index than the photosensitive polymer used to record the diffraction gratings 1112 and 1122. In some examples, the respective substrates 1114 and 1124 are placed in front of the carrier films 1116 and 1126.

Adjacent layers or components within the optical diffraction device 1100 can be bonded together using one or more intermediate layers selected from OCA, UV-curable or thermosetting optical adhesives, optical contacts, or exponentially matching fluids. For example, a first diffraction component 1110 (e.g., substrate 1114) can be bonded to a field lattice substrate 1102 through an intermediate layer 1101, for example, an OCA layer. The first diffraction component 1110 and a second diffraction component 1120 (e.g., carrier film 1116 and substrate 1124) can be bonded together through another intermediate layer 1103, for example, an OCA layer. The optical diffraction device 1100 (e.g., carrier film 1126) can be bonded to the display cover glass 1130 through an intermediate layer 1105, for example, an OCA layer.

As shown in Figure 11, each of the first diffraction gratings 1112 and the second diffraction grating 1122 is configured to diffract light of the corresponding color incident at their respective angles of incidence in the first order at their respective diffraction angles and in the zero order at their respective angles of incidence, and to transmit light of a different color at different angles of incidence, for example, for Bragg selectivity. Therefore, no crosstalk can exist between light of different colors diffracted individually by the corresponding diffraction gratings. Each color of light can be polarized. The polarization states of the first-order diffracted light of different colors can be the same, for example, s or p. The respective diffraction angles for light of different colors can be the same, for example, substantially perpendicular.

The optical diffraction device 1100 may include a first reflective layer (or blocking layer) between the first grating 1112 and the second grating 1122. The first grating 1112 is configured to diffract blue light incident at a first incidence angle _θb , for example 78.4°, at a certain diffraction angle, for example, firstly at 0° and zero-order at the first incidence angle. The refractive index of the first reflective layer, for example, is configured to completely reflect the blue light diffracted at the first incidence angle but to transmit green light incident at a second incidence angle _θg , for example 76.5°. For example, the refractive index of the first reflective layer is lower than the refractive index of the layer immediately preceding the first reflective layer, for example, the first grating 1112. The first reflective layer may be a suitable layer between the first grating 1112 and the second grating 1122. In some examples, the first reflective layer is a carrier film 1116, as shown in Figure 11.

Similarly, the optical diffraction device 1100 may include a second reflective layer after the second grating 1122 and before the display cover glass 1130. The second grating 1112 is configured to diffract green light incident at a second incidence angle _θg , for example 76.5°, firstly at a certain diffraction angle, for example 0°, and zero-order at the second incidence angle. The refractive index of the second reflective layer, for example, is configured to completely reflect the green light diffracted at the second incidence angle. The second reflective layer may be a suitable layer between the second grating 1122 and the cover glass 1130. In some examples, the second reflective layer is an intermediate layer 1105, as shown in Figure 11.

The blue and green light, completely reflected by the corresponding reflective layer, is reflected back to the optical diffraction device 1100, relative to the side surface of the optical diffraction device 1100. As illustrated in Figure 11, the side surface can be coated with a light absorber 1104, for example, a black coating, to absorb the completely reflected blue and green light diffracted at the zeroth order by the corresponding diffraction grating.

The field lattice substrate 1102 can be sufficiently thick to allow regenerated reference beams of different colors to enter its edges. The field lattice substrate 1102 can also be configured to completely contain the regenerated reference beam so that a viewer or observer cannot insert their finger or other object into the regenerated reference beam. Therefore, the viewer cannot obstruct the regenerated reference beam, which improves laser safety because the viewer cannot place their eye (or any reflecting or focusing element) into the full-power regenerated reference beam. An optical diffraction device 1100 with the field lattice substrate 1102 can be significantly more compact than when the regenerated reference beam is incident from air onto the front surface of the optical diffraction device 1100.

Because blue and green light are incident at relatively large regeneration reference angles (or angles of incidence), e.g., angles exceeding 70°, Fresnel reflection can be significant from the layer interface (for both P and S polarizations) and can increase rapidly with increasing regeneration reference angles. Since the optical diffraction device 1100 includes several interfaces between materials of different refractive indices, Fresnel reflection losses from each such interface increase the substantially attenuation of the regenerated output light, which can cause substantially reduced regenerated optical power at each diffraction grating, particularly the grating closest to the display, e.g., the G grating 1122. In some examples, the regeneration reference angle (or angle of incidence) for light of a particular color can be chosen to be just large enough to reliably receive TIR, but not so large so that Fresnel losses can be reduced.

Figures 13A-13C illustrate the relationship between diffracted regenerated reference beam power (solid line) and reflected or blocked (dashed line) regenerated reference beam power with different incident angles for blue light (Figure 13A), green light (Figure 13B), and red light (Figure 13C). The diffracted regenerated reference beam power may be the beam irradiated onto the cover glass of the display 594 in Figure 5H, adjacent to the optical diffraction device 598 in Figure 5H.

As illustrated in Figure 13A, for blue light, plot 1302 shows the diffracted regenerated reference beam power (or blue illumination power of the display) as the regenerated reference beam angle (e.g., angle of incidence in the glass) increases, and plot 1304 shows the reflected regenerated reference beam power from the corresponding reflective layer as the regenerated reference beam angle increases. As illustrated in Figure 13B, for green light, plot 1312 shows the diffracted regenerated reference beam power (or green illumination power of the display) as the regenerated reference beam angle (e.g., angle of incidence in the glass) increases, and plot 1314 shows the reflected regenerated reference beam power from the corresponding reflective layer as the regenerated reference beam angle increases. As illustrated in Figure 13C, for red light, plot 1322 shows the diffracted regenerated reference beam power (or red illumination power of the display) as the regenerated reference beam angle (e.g., angle of incidence in the glass) increases, and plot 1324 shows the reflected regenerated reference beam power from the corresponding reflective layer as the regenerated reference beam angle increases.

The regeneration reference angles for different colored light can be selected to be large enough for each color of light so that the corresponding reflective layer can completely reflect the color of the light with 100% reflection, while the regeneration reference angle can be small enough so that Fresnel loss does not substantially eliminate the diffracted regeneration reference beam or irradiation within the display's cover glass. As an example, the diffraction efficiency of each grating is 50% for blue, 60% for green, and 70% for red. The lower layer of the optical diffraction device is parallel to the display's cover glass. The diffraction angle of the regenerated object beam for each color is -6°. As shown in Figures 13A, 13B, and 13C, if the regeneration reference angles are 78.4° for blue light at 460 nm, 76.5° for green light at 520 nm, and 73.5° for red light at 640 nm, the final object beam power within the display's cover glass is 46.8% for blue, 33.1% for green, and 43.0% for red.

Figure 12A illustrates an exemplary optical diffraction device 1200, which includes three color diffraction gratings and corresponding reflective layers for individually diffracting three colors of light. For illustrative purposes, the device 1200 is configured for blue light, green light, and red light.

The optical diffraction device 1200 includes a first diffraction component 1210 having a first diffraction grating 1212 for blue light, a second diffraction component 1220 having a second diffraction grating 1222 for green light, and a third diffraction component 1230 having a third diffraction grating 1232 for red light. Each of the first diffraction gratings 1212, the second diffraction grating 1222, and the third diffraction grating 1232 may be a holographic grating, such as a Bragg grating or a volume grating. Each of the first diffraction gratings 1212, the second diffraction grating 1222, and the third diffraction grating 1232 can be independently recorded and immobilized on a recording medium, such as a photosensitive polymer such as a photopolymer.

The first diffraction component 1210, the second diffraction component 1220, and the third diffraction component 1230 can be stacked together on a field lattice substrate 1202 along a certain direction, for example, the Z direction. The field lattice substrate 1202 may be an optically transparent substrate, such as a glass substrate. The optical diffraction device 1210 may be located in front of a display such as an LCOS, for example, the display 594 in Figure 5H. For example, the optical diffraction device 1200 may be placed on the cover glass 1240 of the display through an intermediate layer, or it may be separated by a gap, such as an air gap.

Similar to the first diffraction element 1010, the second diffraction element 1020, and the third diffraction element 1030 in Figures 10A and 10B, each of the first diffraction element 1210, the second diffraction element 1220, and the third diffraction element 1230 may include, on both sides of their respective diffraction gratings 1212, 1222, and 1232, their respective substrates 1214, 1224, and 1234, and their respective carrier films 1216, 1226, and 1236. Each diffraction grating 1212, 1222, and 1232 is located between their respective substrates 1214, 1224, and 1234 and their respective carrier films 1216, 1226, and 1236. The respective substrates 1214, 1224, and 1234 and their respective carrier films 1216, 1226, and 1236 can be arranged in a sequence to reduce refractive index mismatch, and therefore Fresnel reflection. Each of the substrates 1214, 1224, and 1234 can be a glass substrate having the same or a similar refractive index as the field lattice substrate 1202. Each of the carrier films 1216, 1226, and 1236 can be a TAC film. The TAC film can have a lower refractive index than the photosensitive polymer. In some examples, each of the substrates 1214 and 1224 is placed in front of the carrier films 1216 and 1226. Substrate 1234 is placed after the carrier film 1236.

Adjacent layers or components within the optical diffraction device 1100 can be bonded together using one or more intermediate layers selected from OCA, UV-curable or thermosetting optical adhesives, optical contacts, or exponentially matching fluids. For example, a first diffraction component 1210 (e.g., substrate 1214) can be bonded to a field lattice substrate 1202 through an intermediate layer 1201, for example, an OCA layer. The first diffraction component 1210 and the second diffraction component 1220, for example, a carrier film 1216 and a substrate 1224, can be bonded together through another intermediate layer 1203, for example, an OCA layer. The second diffraction component and the third diffraction components 1220 and 1230, for example, a carrier film 1226 and a carrier film 1236, can be bonded together through another intermediate layer 1205, for example, an OCA layer. The optical diffraction device 1200 (e.g., substrate 1234) can be attached to the display cover glass 1240 via an intermediate layer 1207, for example, an OCA layer.

As shown in Figure 12A, each of the first diffraction gratings 1212, the second diffraction grating 1222, and the third diffraction grating 1232 is configured to diffract light of the corresponding color incident at each respective angle of incidence in the first order at each diffraction angle and in the zero order at each respective angle of incidence, and to transmit light of a different color at a different angle of incidence, for example, for Bragg selectivity. Therefore, there can be little to no crosstalk between the different colored lights diffracted individually by the corresponding diffraction gratings. Each color of light can be polarized. The polarization states of the first-order diffracted different colored lights can be the same, for example, s or p. The respective diffraction angles for different colored lights can be the same, for example, substantially perpendicular.

As discussed above in Figures 13A, 13B, and 13C, different incident angles _θb , _θg , and _θr (or regeneration reference angles) for different colored light (blue, green, and red) can be selected, for example, to be 78.4°, 76.5°, and 73.5°. The optical diffraction device 1200 may include a first reflective layer (or blocking layer) between the first grating 1212 and the second grating 1222. The first grating 1212 is configured to diffract blue light incident at a first incident angle _θb at a certain diffraction angle, for example, first-order at 0° and zero-order at the first incident angle. The refractive index of the first reflective layer, for example, is configured to completely reflect the blue light diffracted at the first incident angle, but to transmit green light incident at a second incident angle _θg and red light incident at a third incident angle _θr . For example, the refractive index of the first reflective layer is lower than that of the layer immediately preceding the first reflective layer, e.g., the first grating 1212. The first reflective layer may be a suitable layer between the first grating 1212 and the second grating 1222. In some examples, the first reflective layer is a carrier film 1216, as shown in Figure 12A. Total internal reflection occurs at the interface between the first grating 1212 and the carrier film 1216. The completely reflected blue light that is not diffracted (or transmitted) in the zeroth order is reflected backward relative to the layer above the first reflective layer and can be absorbed by a light absorber 1204 coated on the side of the optical diffraction device 1200.

The optical diffraction device 1200 may include a second reflective layer (or blocking layer) between the second grating 1222 and the third grating 1232. The second grating 1222 is configured to diffract green light incident at a second incidence angle _θg in a first order at a certain diffraction angle, for example, 0°, and zero order at the second incidence angle. The refractive index of the second reflective layer, for example, is configured to completely reflect the green light diffracted at the second incidence angle, but to transmit red light incident at a third incidence angle _θr . For example, the refractive index of the second reflective layer is lower than the refractive index of the layer immediately preceding it. The second reflective layer may be a suitable layer between the second grating 1222 and the third grating 1232. In some examples, the second reflective layer is an intermediate layer 1205, as shown in Figure 12A. Total internal reflection occurs at the interface between the carrier film 1226 and the intermediate layer 1205. The perfectly reflected green light, which is not diffracted (or transmitted) in the zero order, is reflected backward against the layer above the second reflective layer and can be absorbed by the light absorber 1204.

The optical diffraction device 1200 may include a third reflective layer after the third grating 1232 and before the display cover glass 1240. The third grating 1232 is configured to diffract red light incident at a third incidence angle _θr in the first order at a certain diffraction angle, for example, 0°, and in the zero order at the third incidence angle. The refractive index of the third reflective layer, for example, is configured to completely reflect the red light diffracted at the third incidence angle. The third reflective layer may be a suitable layer between the third grating 1232 and the cover glass 1240. In some examples, the third reflective layer is an intermediate layer 1207 between the substrate 1234 and the cover glass 1240, as shown in Figure 12A. The completely reflected red light that is not diffracted (or transmitted) in the zero order is reflected backward against the layer above the second reflective layer and can be absorbed by the light absorber 1204.

The field lattice substrate 1202 can be sufficiently thick so that regenerated reference beams of different colors enter its edges. The field lattice substrate 1202 can also be configured to completely contain the regenerated reference beam so that a viewer or observer cannot insert their finger or other object into the regenerated reference beam. Therefore, the viewer cannot obstruct the regenerated reference beam, which improves laser safety because the viewer cannot place their eye (or any reflecting or focusing element) into the full-power regenerated reference beam. An optical diffraction device 1200 with the field lattice substrate 1202 can be significantly more compact than when the regenerated reference beam is incident from air onto the front surface of the optical diffraction device 1200.

As shown in Figure 12A, the field lattice substrate 1202 may have a rectangular cross-section in the XZ plane. Light of different colors is incident on the field lattice substrate 1202 from the side. Figure 12B illustrates another exemplary optical diffraction device 1250, which includes a wedge-shaped field lattice substrate 1252. A wedge-shaped angle can be selected between the side (or input surface of the light beam) 1251 of the substrate 1252 and the top layer 1253 of the substrate 1252, and/or the side can be AR coated. Thus, the optical path taken by any light beam returning from the optical diffraction device 1250 and the display to the field lattice substrate 1252 can be appropriately blocked, attenuated, or directed to reduce or eliminate back reflection to the optical diffraction device 1250 and the display. The optical diffraction device 1250 may include a corresponding light absorber 1254 coated on the opposite surface, which may be shorter than the light absorber 1204 in Figure 12A.

Figure 12C illustrates a further exemplary optical diffraction device 1270, including a field grating substrate 1272 having a wedge-shaped input surface 1271. The wedge-shaped input surface 1271 may be configured to reduce Fresnel losses of input light of different colors. The wedge-shaped input surface 1271 may be configured such that input light of different colors is incident on the input surface 1271 at substantially perpendicular incidence and incident on the corresponding diffraction grating at different incidence angles (or regeneration reference angles). The wedge-shaped input surface 1271 may be configured to refract the input light of different colors to a desired angle for each color within the diffraction device, and from a convenient direction and angle in the air. For example, the wedge-shaped input surface 1271 may have a wedge angle such that the angle in air moves the input beam parallel to the front of the diffraction device or from the space behind the front of the diffraction device.

By forming an AR coating on the front surface 1273 of the field grid substrate 1272, the reflection of ambient light toward the viewer can be reduced or eliminated. Furthermore, by forming an AR coating on the back surface of the optical diffraction device 1270 closest to the display, undesirable reflections of light reflected and/or diffracted from the display toward the viewer can also be reduced or eliminated.

In some implementations, one or more layers in an optical diffraction device, such as the optical diffraction device 1100 in Figure 11, 1200 in Figure 12A, 1250 in Figure 12B, or 1270 in Figure 12C, can be slightly wedge-shaped, thereby allowing for fine-tuning of the TIR and Fresnel reflections in each layer. The layers may also be configured to reduce or eliminate the visibility of Newton's rings or interference fringes that may occur between any pair of substantially parallel surfaces in the optical diffraction device when using a narrowband light source, such as a laser diode.

Exemplary Manufacturing Process Figure 14A is a flowchart of an exemplary process 1400 for manufacturing an optical diffraction device including a diffraction structure and a corresponding color-selective polarizer. The optical diffraction device may be the optical diffraction device 598 in Figure 5H, 598A in Figure 5I, 598B in Figure 5J, or 598C in Figure 5K, the optical diffraction device 900 in Figures 9A and 9B, or the optical diffraction device 1000 in Figures 10A and 10B.

A first diffraction component for a first color is manufactured (1402). The first diffraction component may be the first diffraction component 910 in Figures 9A and 9B, or 1010 in Figures 10A and 10B. The first diffraction component includes a first diffraction structure formed on a recording medium, for example, the B-grille 912 in Figures 9A and 9B, or the B-grille 1012 in Figures 10A and 10B. The first diffraction structure is configured to diffract a reconstructed reference light of a first color (or light of a first color) incident on the first diffraction structure at a first angle of incidence and in a first polarization state, with a first diffraction efficiency and at a first diffraction angle. The first diffraction efficiency may be substantially higher than the diffraction efficiency of the first diffraction structure to diffract light of a first color or light of another different color incident on the first diffraction structure at a first angle of incidence and in a second polarization state different from the first polarization state, for example, for polarization selectivity. The first polarization state can be s-polarization, and the second polarization state can be p-polarization.

The first diffraction structure may be a holographic grating, such as a volume grating or a Bragg grating. The thickness of the recording medium may be more than an order of magnitude greater than the wavelength of the first recording object beam, for example, 30 times. In some examples, the first angle of incidence may be the Bragg angle. The first diffraction efficiency may be substantially higher than the diffraction efficiency of the first diffraction structure, which diffracts light of a first color or another different color incident in a first or second polarization state at an angle of incidence different from the first angle of incidence, for example, due to Bragg selectivity.

The recording medium may include a photosensitive material, such as a photosensitive polymer or photopolymer. The first diffraction structure can be formed by exposing the photosensitive material to a first recording object beam at a first recording object angle and simultaneously to a first recording reference beam at a first recording reference angle. The first recording object beam and the first recording reference beam may, for example, have the same wavelength and the same first polarization state from the same light source.

In some cases, the first color of light used for regeneration may be broader than or the same wavelength range as the first recording reference beam or the first recording object beam. For example, the first recording reference beam and the first recording object beam may be laser beams, and the first color of light for regeneration may be a laser diode beam. In some cases, the first recording reference beam and the first recording object beam may correspond to colors different from the first color of the first color of light. For example, green laser light may be used to record a diffraction grating for red light.

The first incident angle of light of the first color may be substantially identical to the first recording reference angle, and the first diffraction angle may be substantially identical to the first recording object angle. In some examples, the first recording reference angle is in the range of 70 to 90 degrees, for example, 80 to 90 degrees. In some examples, the first recording object angle is in the range of -10 to 10 degrees, for example, -7 to 7 degrees, 0 degrees, or 6 degrees. In some examples, the sum of the first recording reference angle and the first recording object angle within the photosensitive material is substantially identical to 90 degrees.

The first diffraction structure can be fixed in the recording medium by, for example, UV curing or thermal curing. In some examples, the first diffraction component includes a carrier film, such as a TAC film, on the recording medium. In some examples, the first diffraction component includes a diffraction substrate, such as a glass substrate. The recording medium may be located between the carrier film and the diffraction substrate.

A second diffraction component for the second color is manufactured (1404). The second diffraction component may be the second diffraction component 920 in Figures 9A and 9B, or 1020 in Figures 10A and 10B. The second diffraction component includes a second diffraction structure formed on the second recording medium, for example, the B-grille 922 in Figures 9A and 9B, or the R-grille 1022 in Figures 10A and 10B. The second diffraction structure is configured to diffract a regenerated reference light of the second color (or light of the second color) incident on the second diffraction structure at a second incidence angle and in a first polarization state, with a second diffraction efficiency and a second diffraction angle. The second diffraction efficiency may be substantially higher than the diffraction efficiency of the second diffraction structure to diffract light of the second color or light of another different color incident at a second incidence angle or an incidence angle different from the second incidence angle and in a second polarization state.

The second diffraction structure can be manufactured in the same manner as the first diffraction structure, as described above. The first and second diffraction structures can be manufactured independently. The second diffraction component may also include a carrier film and a diffraction substrate.

The first and second diffraction components can be configured such that the first and second diffraction angles are substantially identical, for example, substantially perpendicular to each other. The first and second incidence angles may also be substantially identical.

A color-selective polarizer is positioned between the first optical diffraction element and the second optical diffraction element (1406). The color-sensitive polarizer may be the GM filter 906 in Figures 9A and 9B, or the MG filter 1006 in Figures 10A and 10B. The optical diffraction structure may include a field lattice substrate, for example, the substrate 902 in Figures 9A and 9B, or the substrate 1002 in Figures 10A and 10B. The first optical diffraction element, the color-selective polarizer, and the second optical diffraction element can be sequentially stacked on the field lattice substrate such that light of the first color and light of the second color are incident on the first optical diffraction element before the second optical diffraction element. The color-selective polarizer may be configured to rotate the polarization state of the light of the second color, for example, from a second polarization state to a first polarization state, so that light of the second color can be incident on the second diffraction structure in a first polarization state. In some cases, the color-selective polarizer can rotate the polarization state of the light of the first color. In some cases, color-selective polarizers are configured not to rotate the polarization state of light of a first color.

In some implementations, an additional color-selective polarizer is positioned in front of the first diffraction element. For example, the additional color-selective polarizer may be located between the field lattice substrate and the first diffraction element. The additional color-selective polarizer may be the BY filter 904 in Figures 9A and 9B, or the BY filter 1004 in Figures 10A and 10B. The additional color-selective polarizer is configured to rotate the polarization state of the light of the first color, for example, from a second polarization state to a first polarization state, so that the light of the first color is incident on the first diffraction structure in a first polarization state. In some cases, the additional color-selective polarizer can rotate the polarization state of the light of the second color, for example, from a first polarization state to a second polarization state, so that the light of the second color is incident on the first diffraction structure in a second polarization state. In some cases, the additional color-selective polarizer is configured not to rotate the polarization state of the second color of light, so that the polarization state of the second color of light is incident on the first diffraction structure in the second polarization state.

Adjacent components within an optical diffraction device can be joined together through an intermediate layer. The intermediate layer may be an OCA layer, a UV-curable or thermosetting optical adhesive, an optical contact, or an exponentially matched fluid.

In some implementations, process 1400 may further include forming a third optical diffraction component. The third diffraction component includes a third diffraction structure formed on the third recording medium, for example, the G-gratt 1032 in Figures 10A and 10B. The third diffraction structure is configured to diffract a reconstructed reference light of a third color (or light of a third color) incident on the third diffraction structure at a third incidence angle and in a first polarization state, with a third diffraction efficiency and a third diffraction angle. The third diffraction efficiency may be substantially higher than the diffraction efficiency of the third diffraction structure to diffract light of a third color or light of another different color incident at an incidence angle different from the second or third incidence angle and in the third polarization state.

The third diffraction structure can be manufactured in the same manner as the first diffraction structure, as described above. The first, second, and third diffraction structures can be manufactured independently. The third diffraction component may also include a carrier film and a diffraction substrate. The first, second, and third diffraction components can be configured such that the first, second, and third diffraction angles are substantially identical to each other, for example, substantially perpendicular. The first, second, and third incident angles may be substantially identical to each other.

A second color-selective polarizer can be positioned between a second optical diffraction element and a third optical diffraction element. The second color-sensitive polarizer may be a YG filter as shown in Figures 10A and 10B. The second color-selective polarizer can consist of two or more sub-polarizers, for example, an RC filter 1008-1 and a GM filter 1008-2 as shown in Figures 10A and 10B. In some examples, the second color-selective polarizer can be mounted first on the third diffraction element, and then mounted on the second diffraction element. In some examples, the second color-selective polarizer can be mounted first on the second diffraction element, and then mounted on the third diffraction element. The second color-selective polarizer can be configured to rotate the polarization state of light of a third color from a second polarization state to a first polarization state so that light of a third color is incident on the third diffraction structure in a first polarization state. The second color-selective polarizer can be configured to rotate the polarization state of light of the second color from, for example, the first polarization state to the second polarization state, without rotating the polarization state of light of the first color.

The third color-selective polarizer can be sequentially arranged on the third optical diffraction component such that the third optical diffraction component is located between the second and third color-selective polarizers. The third color-selective polarizer may be the MG filter 1040 shown in Figures 10A and 10B. The third color-selective polarizer is configured to rotate the polarization states of the first and second colored light, for example, from the second polarization state to the first polarization state, without rotating the first polarization state of the third colored light, so that the diffracted first colored light, second colored light, and third colored light have the same polarization state.

Figure 14B is a flowchart of an exemplary process 1450 for manufacturing an optical diffraction device including a diffraction structure and a corresponding reflective layer. The optical diffraction device may be the optical diffraction device 598 in Figure 5H, 598A in Figure 5I, 598B in Figure 5J, or 598C in Figure 5K, the optical diffraction device 1100 in Figure 11, or the optical device 1200 in Figure 12A, 1250 in Figure 12B, or 1270 in Figure 12C.

A first optical diffraction component is formed (1452). The first diffraction component may be the first diffraction component 1110 in Figure 11, or 1210 in Figures 12A, 12B, or 12C. The first diffraction component includes a first diffraction structure stored in a first recording medium. The first diffraction structure is configured to diffract light of a first color incident at a first incidence angle in the first order at a first diffraction angle and in the zero order at a first incidence angle. The power of the first-order light of the first color may be substantially higher than the power of the zero-order light of the first color.

The first diffraction structure may be a holographic grating, such as a volume grating or a Bragg grating. The thickness of the recording medium may be more than an order of magnitude greater than the wavelength of the first recording object beam, for example, 30 times. In some examples, the first angle of incidence may be the Bragg angle. The first diffraction efficiency may be substantially higher than the diffraction efficiency of the first diffraction structure, which, for example due to Bragg selectivity, diffracts the first color of light or another different color of light at angles of incidence different from the first angle of incidence. Light incident at different angles of incidence can be transmitted through the first diffraction structure.

The recording medium may include a photosensitive material, such as a photosensitive polymer or photopolymer. The first diffraction structure can be formed, for example, by exposing the photosensitive material to a first recording object beam at a first recording object angle and simultaneously to a first recording reference beam at a first recording reference angle, as in step 1402 of Figure 14A. The first recording object beam and the first recording reference beam may have the same wavelength and the same polarization state from the same light source, for example. The first incident angle of light of a first color may be substantially the same as the first recording reference angle, and the first diffraction angle may be substantially the same as the first recording object angle. In some examples, the first recording reference angle is in the range of 70 to 90 degrees, for example, 70 to 80 degrees. In some examples, the first recording object angle is in the range of -10 to 10 degrees, for example, -7 to 7 degrees, 0 degrees, or 6 degrees. The first diffraction structure can be fixed in the recording medium, for example, by UV curing or thermal curing. In some examples, the first diffraction component includes a carrier film, such as a TAC film, on the recording medium. In some examples, the first diffraction component includes a diffraction substrate, such as a glass substrate. The recording medium may be located between the carrier film and the diffraction substrate.

A second optical diffraction component is formed (1454). The second diffraction component may be the second diffraction component 1120 in Figure 11, or 1220 in Figures 12A, 12B, or 12C. The second diffraction component includes a second diffraction structure stored on a second recording medium. The second diffraction structure is configured to diffract light of a second color incident at a second incidence angle, firstly at the second diffraction angle and zero-order at the second incidence angle. The power of the first-order second-color light may be substantially higher than the power of the zero-order second-color light.

The second diffraction structure can be manufactured in the same manner as the first diffraction structure in step 1452. The first and second diffraction structures can be manufactured independently. The second diffraction component may also include a carrier film and a diffraction substrate.

The first and second diffraction components can be configured such that the first and second diffraction angles are substantially identical, for example, substantially perpendicular to each other. The first and second incident angles are different. The first and second incident angles can be determined, for example, according to those shown in Figures 13A-13C. In some examples, the light of the first color has a shorter wavelength than the light of the second color, and the first incident angle is greater than the second incident angle.

The first reflective layer is positioned between the first diffraction structure and the second diffraction structure (1456). The first reflective layer may be the reflective layer 1116 in Figure 11, or 1216 in Figures 12A, 12B, or 12C. The first reflective layer is configured to completely reflect light of the first color incident at a first angle of incidence so that light of the first color that is not diffracted (or transmitted) in the zeroth order can be reflected backward to a layer in front of the first reflective layer without propagating to a display behind the optical diffraction device. The first reflective layer may be configured to have a smaller refractive index than the layer of the first optical diffraction component directly adjacent to the first reflective layer so that light of the first color having a first angle of incidence is completely reflected by the interface between the first reflective layer and the layer of the first optical diffraction component without completely reflecting light of the second color having a second angle of incidence. The first reflective layer may be any suitable layer between the first diffraction structure and the second diffraction structure. For example, the first reflective layer may be a carrier film for the first diffraction component.

The second reflective layer is positioned behind the second diffracting structure (1458). The second reflective layer may be the reflective layer 1105 in Figure 11, or 1205 in Figures 12A, 12B, or 12C. The second reflective layer is configured to completely reflect second color light incident at a second incidence angle, so that second color light that is not diffracted (or transmitted) at the zeroth order can be reflected back to the layer in front of the second reflective layer without propagating to the display behind the optical diffracting device.

A light absorber can be formed on the side surface of an optical diffraction device. The light absorber may be the light absorber 1104 in Figure 11, 1204 in Figures 12A and 12C, or 1254 in Figure 12B. The light absorber is configured to absorb perfectly reflected light of a first and second color.

In some implementations, a third optical diffraction component is formed, including a third diffraction structure. The third diffraction component may be the third diffraction component 1230 in Figures 12A, 12B, or 12C. The third diffraction structure may be the third diffraction structure 1232 in Figures 12A, 12B, or 12C. The third diffraction structure is configured to diffract light of a third color incident at a third incidence angle, firstly at the third diffraction angle, and then zero at the third incidence angle. The power of the first-order third color light may be substantially higher than the power of the zero-order third color light. The first, second, and third diffraction angles may be substantially the same as each other. The third incidence angle may be different from the first and second incidence angles. Each of the first and second reflective layers may be configured to transmit light of a third color having a third incidence angle. A second reflective layer can be placed between the second and third diffraction structures. The third diffraction structure can be manufactured in the same manner as the first diffraction structure in step 1452. The first, second, and third diffraction structures can be manufactured independently. The third diffraction component may also include a carrier film and a diffraction substrate.

A third reflective layer can be positioned behind the third diffracting structure. The third reflective layer may be the third reflective layer 1207 in Figures 12A, 12B, or 12C. The third reflective layer is configured to completely reflect third-color light with a third incident angle such that light of a third color that is not diffracted (or transmitted) at the zeroth order is reflected backward from the layer preceding the third reflective layer and can be absorbed by a light absorber coated on the side surface of the optical diffracting device.

In some implementations, the first reflective layer includes a first carrier film of the first optical diffraction component. The second diffraction substrate of the second diffraction component is attached to the first carrier film of the first diffraction component by a first intermediate layer, such as an OCA layer. The second carrier film of the second diffraction component is attached to the third carrier film of the third optical diffraction component by a second intermediate layer, and the second reflective layer may include the second intermediate layer. The third reflective layer can be attached to the third diffraction substrate of the third diffraction component.

Process 1450 may include arranging the first diffraction element on a substrate in front of the first diffraction element. The substrate may be the field lattice substrate 1102 in Figure 11, 1202 in Figure 12A, 1252 in Figure 12B, or 1272 in Figure 12C. The substrate may include a front and a back surface. The front surface of the first diffraction element may be attached to the back surface of the substrate via a refractive index matching material or an OCA layer.

In some examples, the substrate includes sides angled relative to the back surface, and the substrate is configured to receive light of multiple different colors on its sides. The substrate can be configured so that light of multiple different colors is incident on the sides at substantially the same incident angle as 0 degrees, and incident on the back surface at their respective regeneration reference angles.

The embodiments of this disclosure can provide a method for manufacturing a device including an optical diffraction device and a display. The display may be the display 594 in Figure 5H, 594A in Figure 5I, 594B in Figure 5J, or 594C in Figure 5K. The optical diffraction device may be the optical diffraction device 598 in Figure 5H, 598A in Figure 5I, 598B in Figure 5J, or 598C in Figure 5K, the optical diffraction device 900 in Figures 9A and 9B, the optical diffraction device 1000 in Figures 10A and 10B, the optical diffraction device 1100 in Figure 11, or the optical device 1200 in Figure 12A, 1250 in Figure 12B, or 1270 in Figure 12C.

The method may include forming an optical diffraction device according to process 1400 in Figure 14A or process 1450 in Figure 14B. In some implementations, the optical diffraction device may include one or more color-selective polarizers and one or more reflective layers for multiple different colors of light. The optical diffraction device can be manufactured according to a combination of processes 1400 and 1450.

The method may further include arranging the optical diffraction device and the display such that the optical diffraction device is configured to diffract light of multiple different colors onto the display.

In some implementations, the optical diffraction device and the display can be arranged such that the back surface of the optical device is separated from the front surface of the display by a gap, such as an air gap. The method may further include forming an anti-reflective coating on at least one of the front surface of the display or the back surface of the optical diffraction device.

In some implementations, the optical diffraction device and the display can be arranged by mounting the back surface of the optical diffraction device on the front surface of the display through an intermediate layer. The intermediate layer may be configured to have a refractive index lower than that of the layers of the optical diffraction device, such that each of the multiple different colors of light diffracted in the zeroth order by the optical diffraction device is completely reflected at the interface between the intermediate layer and the layers of the optical diffraction device.

An optical diffraction device is configured to diffract light of multiple different colors at diffraction angles that are substantially identical to each other. Each diffraction angle is in the range of -10° to 10°, for example, -7° to 7°, and can be 0° or 6°. A display can be configured to rediffract the diffracted light of the colors backward through the optical diffraction device. A region of the optical diffraction device can cover a region of the display. The optical diffraction device may include a substrate in front of the optical device, and can be configured to receive light of multiple different colors on the side of the substrate that is angled relative to the back surface of the substrate.

The implementation embodiments of this disclosure can provide a method for operating an optical diffraction device. The optical diffraction device may be the optical diffraction device 598 in Figure 5H, 598A in Figure 5I, 598B in Figure 5J, or 598C in Figure 5K, the optical diffraction device 900 in Figures 9A and 9B, the optical diffraction device 1000 in Figures 10A and 10B, the optical diffraction device 1100 in Figure 11, or the optical device 1200 in Figure 12A, 1250 in Figure 12B, or 1270 in Figure 12C. The optical diffraction device can operate to convert an incident beam containing light of multiple different colors into individually diffracted light of each color.

The implementation embodiments of this disclosure can provide a method for operating a system including an optical diffraction device and a display. The optical diffraction device may be the optical diffraction device 598 in Figure 5H, 598A in Figure 5I, 598B in Figure 5J, or 598C in Figure 5K, the optical diffraction device 900 in Figures 9A and 9B, the optical diffraction device 1000 in Figures 10A and 10B, the optical diffraction device 1100 in Figure 11, or the optical device 1200 in Figure 12A, 1250 in Figure 12B, or 1270 in Figure 12C. The display includes a plurality of display elements. The display may be the display 594 in Figure 5H, 594A in Figure 5I, 594B in Figure 5J, or 594C in Figure 5K. The method can be performed by a controller, for example, the controller 112 in Figure 1A or 592 in Figure 5H.

The method may include transmitting at least one timing control signal to an irradiator to activate the irradiator and emit light of multiple different colors into the optical diffraction device, so that the irradiator converts light of multiple different colors into light of individually diffracted colors and irradiates the display; and transmitting at least one control signal for each of the multiple display elements of the display so that the light of each individually diffracted color is reflected by the modulated display element to form a multicolor three-dimensional light field corresponding to the respective control signal.

In some implementations, the method may further include: obtaining graphic data containing primitive data for multiple primitives corresponding to an object in three-dimensional space; determining the EM field contribution to each of the multiple display elements of a display by calculating the electromagnetic (EM) field propagation from the primitive to the display element in a three-dimensional coordinate system for each of the multiple primitives; generating the sum of the EM field contributions from the multiple primitives to the display element for each of the multiple display elements; and generating a control signal for each of the multiple display elements based on the sum of the EM field contributions to the display element for modulation of at least one characteristic of the display element. The multicolor three-dimensional light field corresponds to the object.

In some implementations, the method includes sequentially modulating a display with information associated with multiple different colors over a series of periods, and controlling an irradiator to sequentially emit each of the multiple colors of light into the optical device within each period of the series, such that each of the multiple colors of light is diffracted by the optical device toward the display and reflected by the modulated display elements of the display, forming a corresponding three-dimensional light field of each color for an object within each period.

Multiple different colors of light can be diffracted by an optical device at substantially the same diffraction angle relative to a display. The diffraction angle can be in the range of 0 to 10 degrees.

The irradiator and optical diffraction device can be configured so that multiple different colored lights are incident on a first optical diffraction component of the optical diffraction device at their respective incident angles. Each of these incident angles is in the range of 70 to 90 degrees. In some cases, the incident angles are different from each other. In some cases, the incident angles are substantially identical to each other.

An optical diffraction device can include multiple diffraction gratings for multiple different colors. The gratings can include transmission gratings, reflection gratings, or combinations thereof. For example, each of the optical diffraction devices shown in Figures 9A to 12C includes a corresponding transmission grating for a different color. In some implementations, the optical diffraction device can include a combination of transmission and reflection gratings that can be configured for different colors. The optical diffraction device can be configured to diffract incident light in the same direction or back in opposite directions.

Figure 15 illustrates an exemplary optical device 1500 that includes a combination of transmission and reflection diffraction gratings and corresponding reflection layers for each of two colors to diffract two colors of light separately. The optical device 1500 may include a first diffraction component 1510 having a first diffraction grating 1512 for blue light, and a second diffraction component 1520 having a second diffraction grating 1522 for green light. Each of the first diffraction grating 1512 and the second diffraction grating 1522 may be a holographic grating, such as a Bragg grating or a volume grating. However, the first diffraction grating 1512 for blue light is configured to be a transmission grating that diffracts blue light forward when blue light is incident on the grating 1512, while the second diffraction grating 1522 for green light is configured to be a reflection grating that reflects green light backward when green light is incident on the grating 1522. Each of the first diffraction grating 1512 and the second diffraction grating 1522 can independently record and fix data on a recording medium, such as a photosensitive material like a photopolymer.

The first diffraction component 1510 and the second diffraction component 1520 can be stacked together on a field lattice substrate 1502 along a certain direction, for example, the Z direction. The field lattice substrate 1502 may be an optically transparent substrate, such as a glass substrate. The optical diffraction device 1500 may be located in front of a display such as an LCOS, for example, display 594 in Figure 5H, 594A in Figure 5I, 594B in Figure 5J, or 594C in Figure 5K. For example, the optical diffraction device 1500 may be placed on the cover glass 1530 of the display through an intermediate layer, or it may be separated by a gap, such as an air gap.

Similar to the first diffraction component 1110 and the second diffraction component 1120 in Figure 11, each of the first diffraction component 1510 and the second diffraction component 1520 may include their respective substrates 1514 and 1524 and their respective carrier films 1516 and 1526 on both sides of their respective diffraction gratings 1512 and 1522. Each diffraction grating 1512 and 1522 is located between their respective substrates 1514 and 1524 and their respective carrier films 1516 and 1526. Each substrate 1514 and 1524 may be a glass substrate having the same or a similar refractive index as the diffraction grating substrate 1502. Each carrier film 1516 and 1526 may be a TAC film. The TAC film may have a lower refractive index than the photosensitive polymer used to record the diffraction gratings 1512 and 1522. Adjacent layers or components within the optical diffraction device 1500 can be bonded together using one or more intermediate layers selected from OCA, UV-curable or thermosetting optical adhesives, optical contacts, or exponentially matching fluids. For example, a first diffraction component 1510 (e.g., substrate 1514) can be bonded to a field grid substrate 1502 through an intermediate layer 1501, e.g., an OCA layer. The first diffraction component 1510 and a second diffraction component 1520 (e.g., carrier film 1516 and substrate 1524) can be bonded together through another intermediate layer 1503, e.g., an OCA layer. The optical diffraction device 1500 (e.g., carrier film 1526) can be bonded to a display cover glass 1530 through an intermediate layer 1505, e.g., an OCA layer.

As shown in Figure 15, the first diffraction grating 1512 is configured to diffract blue light incident at a first incidence angle _θb , for example 78.4°, at each diffraction angle, for example, firstly perpendicular to the display and zero-order at each incidence angle, and to transmit green light at different incidence angles, for example, for Bragg selectivity. Therefore, there can be no crosstalk between different colored lights diffracted individually by the corresponding diffraction gratings. Each color of light can be polarized. The polarization states of different colored lights diffracted in the first order can be the same, for example, s or p.

The optical diffraction device 1500 may include a first reflective layer (or blocking layer) between the first grating 1512 and the second grating 1522. The first grating 1512 is configured to diffract blue light incident at a first incidence angle _θb , for example, 78.4°, at a certain diffraction angle, for example, firstly at 0° and zero-order at the first incidence angle. The refractive index of the first reflective layer, for example, is configured to completely reflect the blue light diffracted at the first incidence angle but to transmit green light incident at the second incidence angle. For example, the refractive index of the first reflective layer is lower than the refractive index of the layer immediately preceding the first reflective layer, for example, the first grating 1512. The first reflective layer may be a suitable layer between the first grating 1512 and the second grating 1522. In some examples, the first reflective layer is a carrier film 1516, as shown in Figure 15.

The optical diffraction device 1500 may include a second reflective layer after the second grating 1512 and before the display cover glass 1530. The second reflective layer may be an intermediate layer 1505, which can be configured, for example, to completely reflect green light backward to the second grating 1512. The second grating 1512 is then configured to diffract green light incident at a second incidence angle _θg , for example 76.5°, backward towards the display at a certain diffraction angle, for example 0° in the first order, and backward to the optical diffraction device 1500 at the second incidence angle in the zero order.

The blue light, completely reflected by the reflective layer 1516, and the zero-order transmitted green light are located behind the optical diffraction device 1500 relative to its side surface. As illustrated in Figure 15, the side surface is coated with a light absorber 1504, for example, a black coating, so that the zero-order blue and green light can be absorbed by the corresponding transmission and reflection diffraction gratings 1512 and 1522.

Each optical diffraction device equipped with a color-selective polarizer (e.g., as illustrated in Figures 9A–10B) and an optical diffraction device equipped with a reflective layer (e.g., as illustrated in Figures 11–12C and 15) can be considered a one-dimensional beam expander. A one-dimensional beam expander can be configured, for example, to expand an input beam having a certain width and height into an output beam having either the same width and a greater height, or the same height and a greater width, by diffracting the input beam at one or more diffraction angles.

The techniques described herein can also be used to expand an input beam to an output beam that is wider and taller than the input beam, for example, by two-dimensional beam expansion. Two-dimensional beam expansion can be achieved by using a two-dimensional beam expander (or dual beam expander) having at least two one-dimensional beam expanders in series. For example, a first one-dimensional beam expander may be configured to expand the input beam by a first dimension, either width or height, to produce an intermediate beam that is wider or taller than the input beam of the first dimension. A second one-dimensional beam expander may be configured to expand the intermediate beam by a second dimension, either height or width, to produce an output beam that is taller or wider than the intermediate beam of the second dimension. Thus, the output beam can be wider and taller than the input beams of the first and second dimensions.

In such a two-dimensional beam expander configuration, one or both of the one-dimensional beam expanders may utilize color selection technology, and one or both of the one-dimensional beam expanders may utilize reflective layer technology. Each one-dimensional expander may utilize any of the detailed embodiments described herein, including a reflective diffracting element, a refractive diffracting element, or a combination of a reflective diffracting element and a refractive diffracting element. The one-dimensional beam expanders can be positioned in a sequential order in any preferred arrangement or configuration.

In some implementations, an intermediate beam between two such one-dimensional expanders may be coupled from a first one-dimensional expander to a second one-dimensional expander using free-space aerial geometry or through a monolithic or segmented substrate made of, for example, glass or acrylic, and embodying the geometry and functionality of the substrates of both expanders. This coupling can be achieved using one or more coupling elements between the two one-dimensional expanders. The coupling elements may include mirrors, multiple mirrors, or mirror and beam-splitting dichroic components, or thin-film elements of further diffracting elements. The coupling element takes two or more collinear collimated output lights of Similarly, the first one-dimensional expander may have as input collinear collimated outputs of two or more light sources (e.g., laser diodes), each having a different color, or it may have as input two or more independent collimated but non-collinear intermediate beams, each for one color from two or more light sources.

Display Zero-Order Light Suppression A display (e.g., LCoS) includes an array of display elements (e.g., pixels or facesl). There are gaps between the display elements on the display. The gaps occupy a portion of the display area, for example, in the range of 5% to 10%. The display material (e.g., liquid crystal) in these gaps is not controlled by input control signals, and therefore holographic information cannot be input into these gaps; thus, the gaps can be considered dead gaps. In contrast, holographic information can be input into display elements that are controlled (or modulated) to diffract light in order to reconstruct a holographic scene corresponding to the holographic information.

Figure 16 illustrates an example 1600 of incident light 1620 incident on display 1610. Display 1610 may be display 114 in Figure 1A, display 156 in Figure 1B, display 512 in Figure 5A, display 524 in Figure 5B, display 534 in Figure 5C, display 544 in Figure 5D, display 564 in Figure 5E, display 574 in Figure 5F, display 584 in Figure 5G, display 594 in Figure 5H, display 594A in Figure 5I, display 594B in Figure 5J, display 594C in Figure 5K, display 600 in Figure 6A, or display 650 in Figure 6B. Other display configurations are also possible.

As an example, the display 1610 may be an LCoS made of liquid crystal. The display 1610 includes an array of display elements 1612 (e.g., display element 160 in Figure 1B) separated by gaps 1614. Each display element 1612 may have a square (or rectangular or any other preferred) shape with an element width 1613, for example, 5 μm. The display elements 1612 may also have any other preferred shape, for example, a polygon. Adjacent display elements 1612 are separated by gaps 1614 with a gap size 1615, for example, less than 0.5 μm.

The incident light 1620 can be a collimated light beam having a beam size larger than the entire area of the display 1610 so that the incident light 1620 can illuminate the entire area of the display 1610. When the incident light 1620 is incident on the display 1610 at an incident angle _θi , a first portion of the incident light 1620 (e.g., 90% to 95% of the light 1620) illuminates the display element 1612, and a second portion of the incident light 1620 (e.g., 5% to 10% of the light 1620) illuminates the gap 1614. When the display element 1612 is modulated with holographic information (e.g., a hologram corresponding to holographic data), for example by voltage, the first portion of the incident light 1620 can be diffracted by the modulated display element 1612 at a diffraction angle _θd , in the first order, to become diffracted first-order light 1622.

The diffracted primary light 1622 forms a holographic light field that can be a reconstructed cone (or frustum of a cone) 1630 having a viewing angle _θa . The viewing angle _θa depends on one or more characteristics of the display 1610 (e.g., element pitch 1613) and one or more wavelengths of the incident light 1620. In some examples, half of the viewing angle _θa is in the range of 3° to 10°, for example, 5°. For example, with a pitch d = 3.7 μm, the viewing angle _θa is about 7° in air for blue light (λ = 460 nm) and about 10° in air for red light (λ = 640 nm). Light with longer wavelengths corresponds to a larger viewing angle.

Since the gap 1614 of the display 1610 is not modulated by any holographic information, the display 1610 in the gap 1614 functions like a mirror. When a second portion of incident light 1620 enters the gap 1614, the second portion of incident light 1620 can be reflected in the gap 1614 at a reflection angle _θr having the same absolute value as the incident angle _θi . In this disclosure, “A is the same as B” means that the absolute value of A is the same as the absolute value of B, and the direction of A may be the same as or different from the direction of B. The reflected second portion of incident light 1620 can be considered as at least a portion of the display zero-order light 1624. If the incident angle _θi is less than half of the apex angle _θa , for example, _θi = 0°, the display zero-order light 1624 may appear undesirably in the reconstructed cone, which may affect the effect of the holographic scene.

Display zero-order light can also include any other unwanted light from the display, such as light diffracted in the gap, reflected light from display elements, or reflected light from the display cover on the display. Higher-order display zero-order light 1624 can include light diffracted in the gap. In some embodiments, the display 1610 is configured to suppress higher-order display zero-order light by including, for example, irregular or non-uniform display elements having different sizes. The display elements are non-periodic and can form a Voronoi pattern, for example, as illustrated in Figure 6A.

In this disclosure, for illustrative purposes only, the second reflected portion of the incident light is considered representative of the zero-order light of the display.

Figures 17A and 17B illustrate examples 1700 and 1750 of zero-order display light in a holographic scene displayed on a projection screen (Figure 17A) and to the viewer's eye (Figure 17B). Collimated input light 1720 is coupled by an optical device 1710 to illuminate the display 1610 at perpendicular incidence, i.e., θ _i = 0°. The optical device 1710 may be a waveguide, a beam splitter, or an optical diffraction device. For illustrative purposes, the optical device 1710 is the device 598 in Figure 5H, which includes an optical diffraction device, for example, a grating 1714 formed on a substrate 1712. However, as described above, reflective optical devices may be used.

A first portion of the input light 1720 is incident on the display element 1612 of the display 1610, which is modulated with holographic information, and is diffracted by the display element 1612 to become diffracted primary light 1722. A second portion of the input light 1720 is incident on the gap 1614 of the display 1610, and is reflected by the gap 1614 to become at least a portion of the display zero-order light 1724. The diffracted primary light 1722 propagates in space to form a reconstruction cone with a viewing angle, e.g., 10°. Since the angle of incidence, e.g., 0°, is less than half of the viewing angle, e.g., 5°, the display zero-order light 1724 propagating with the same angle of reflection as the angle of incidence, e.g., 0°, is within the reconstruction cone.

As illustrated in Figure 17A, the diffracted primary light 1722 forms a three-dimensional holographic scene, and the two-dimensional cross-section 1732 can be observed on a two-dimensional (2D) projection screen 1730 spaced away from the display 1610 along a direction perpendicular to the display 1610. The display zero-order light 1724 appears as collimated zero-order light 1734, as an undesirable image (e.g., having a rectangular shape) within the holographic scene 1732. As illustrated in Figure 17B, the diffracted primary light 1722 forms a holographic scene 1762 in the eye of the viewer 1760. The display zero-order light 1724 is focused by the lens of the viewer 1760's eye and appears as focused zero-order light 1764, as an undesirable spot within the holographic scene 1762.

To improve the effect of the reconstructed holographic scene and, consequently, the performance of the display system, it is desirable to suppress (or even eliminate) display zero-order light in the reconstructed holographic scene. Implementations of this disclosure provide several techniques for suppressing (or even eliminating) display zero-order light in the reconstructed holographic scene, such as five techniques described below. These techniques can be applied individually or in combination.

Display zero-order light can be suppressed in the reconstructed holographic scene with a light suppression efficiency. Light suppression efficiency is defined as 1 minus the ratio of the amount of display zero-order light in the holographic scene with suppression using the techniques described herein to the amount of display zero-order light in the holographic scene without suppression. In some examples, the light suppression efficiency exceeds a predetermined percentage, e.g., 50%, 60%, 70%, 80%, 90%, or 99%. In some examples, the light suppression efficiency is 100%. That is, all display zero-order light is eliminated in the holographic scene.

In the first technique, referred to as "phase calibration," the phase of the display elements of the display can be adjusted to have a predetermined phase range, for example, [0, 2π]. In this way, the signal-to-noise ratio (S/N) between the holographic scene formed based on the calibrated phase and the zero-order light of the display can be increased.

In the second technique, referred to as "zero-order beam divergence," as illustrated in Figure 18, the display zero-order light beam is diverged by an optical defocusing device (e.g., a concave lens) to have a lower power density. In contrast, the hologram is pre-configured so that a collimated light beam incident on the hologram-modulated display element is diffracted to become a focused light beam. The focused light beam is then refocused by an optical defocusing device to form a holographic scene with a higher power density. Therefore, the display zero-order light beam is diluted or suppressed in the holographic scene.

In the third technique, referred to as "zero-order optical deviation," the zero-order light of the display deviates from the holographic scene, as illustrated in Figures 19A–19C, 20A–20B, 21, and 22. The optical device is configured to couple the input light and illuminate the display at an incident angle greater than half the viewing angle of the reconstructed cone that forms the holographic scene. The zero-order light of the display propagates away from the display at the same reflection angle as the incident angle. The hologram corresponding to the holographic scene is pre-configured so that the diffracted primary light moves away from the display, forming a reconstructed cone as if the incident angle were 0°. Therefore, the zero-order light of the display deviates from the reconstructed cone, and thus from the holographic scene.

In the fourth technique, referred to as "zero-order light blocking," as illustrated in Figures 23A-23B, the zero-order light of the display is first separated from the primary light diffracted by the third technique, and then blocked (or absorbed) by an anisotropic optical element such as an optical blocking component, e.g., a metamaterial layer or louver film. The optical blocking component is configured to transmit light beams with angles smaller than a predetermined angle and block light beams with angles larger than a predetermined angle. The predetermined angle can be smaller than the incident angle of the input light and larger than half the viewing angle of the reconstructed cone.

In the fifth technique, referred to as "zero-order light redirection," as illustrated in Figures 24–33, the zero-order display light is first deviated from the primary light diffracted by the third technique, and then redirected further away from the diffracted primary light by an optical diffraction component, such as a diffraction grating. If the input light contains light of different colors simultaneously or sequentially, as illustrated in Figures 30A–30B, 31A–31B, 32, and 33, the optical diffraction component may include one or more corresponding diffraction gratings configured to diffract light of different colors in different directions in a plane or space to reduce color crosstalk between the different colors.

The five techniques described above are primarily used to suppress the entire amount of reflected zero-order display light. In the sixth technique, the display is configured to suppress the entire amount of higher-order zero-order display light by, for example, using irregular or non-uniform display elements having different sizes and/or shapes. The display elements may not be periodic and may form a Voronoi pattern or Voronoi-patterned display elements. In some implementations, the display may be the display 600 in Figure 6A or the display 650 in Figure 6B.

The following provides a more detailed explanation of the first five technologies.

First Technique – Phase Calibration Phase calibration is a technique that can increase the contrast of a display, for example, by extracting the DC term of the calculated hologram, and can be implemented by software or program instructions. Phase calibration can achieve accuracy that may exceed that of device calibration, which may be poor or unknown.

In some implementations, the hologram includes the phase of each display element of the display. As described above, each phase may be the calculated EM contribution from one or more corresponding objects to each display element. According to phase calibration techniques, the hologram is constructed by adjusting (e.g., scaling and/or shifting) each phase so that the display elements have a predetermined phase range (e.g., [0, 2π]) in order to obtain higher contrast on the display.

Each phase is given by:
It can be adjusted according to
During the ceremony
These represent the initial phase values of each phase,
represents the adjusted phase value for each phase, where A and B are constants for each phase, with A at [0, 1] and B at [0, 2π]. In some examples, A is the same for all display elements. In some examples, B is the same for all display elements. In some examples, A differs for different display elements. In some examples, B differs for different display elements.

In a perfectly calibrated and linearized display system, a pair of (A,B) values (1,0) work optimally to provide the best contrast by demonstrating the highest diffraction efficiency of the input hologram. However, due to nonlinear LC curves and inaccurate display calibration, the phase of each display element is typically not within the range of [0, 2π], and therefore the display contrast is reduced. Since the input light is the same, the zero-order light of the display is the same. Improving the diffraction efficiency of the hologram can lead to higher display contrast and a higher signal-to-noise ratio (S/N ratio) of the holographic scene.

According to phase calibration techniques, display contrast can be improved by scaling and shifting each phase in the phase coordinate system, so that each phase is adjusted to have a certain range, for example, precisely [0, 2π]. In some cases, the range of each adjusted phase may be smaller or larger than the 2π range, depending on the calibration and the maximum phase shift of the working LC. Therefore, for each display, there may be a pair (A, B) that yields the highest diffraction efficiency and the highest signal-to-noise ratio.

The phase of each display element can be adjusted by adjusting constants A and B to maximize the light suppression efficiency of the holographic scene. The light suppression efficiency can be greater than a predetermined percentage, for example, 50%, 60%, 70%, 80%, 90%, or 99%.

In some implementations, the constants A and B are adjusted by machine learning algorithms, such as machine vision algorithms or artificial intelligence (AI) algorithms. In machine vision algorithms, the hologram is designed to create pseudo-random points focused on a plane of transmitted diffuse screen at a specific distance from the display. The hologram is then calculated so that the RGB reconstructed points for each of the three primary colors (red, green, and blue) are perfectly aligned on that plane. The algorithm is then set to find a pair of values (A, B) for each color such that the display contrast is at an acceptable level. Initially, a camera at a specific distance takes a photograph of the pattern on the screen. In the captured image, the brightness of all points (X) is averaged, and a small area (Y) on the background noise is also measured. The X/Y ratio is calculated and checked to see if it is greater than a specific value. If not, the pair of values (A, B) is changed, and the process is automatically repeated until an acceptable pair of values (A, B) is determined.

Second Technique – Zero-Order Beam Divergence Figure 18 illustrates an exemplary system 1800 that suppresses display zero-order light in a holographic scene displayed on a projection screen 1830 by diverging the display zero-order light beam. A beam splitter 1810 is positioned in front of the display 1610 and combines a collimated input light beam 1820 to illuminate the display 1610 with perpendicular incidence. A first portion of the light beam 1820 is diffracted by the display elements modulated by the hologram to become a diffracted first-order light beam 1822, and a second portion of the light beam 1820 is reflected by the gap in the display 1610 to become a display zero-order light beam 1824. An optical divergence component, such as a concave lens 1802, is positioned downstream of the beam splitter 1810 and in front of the projection screen 1830. In some examples, the optical divergent component includes a convex lens positioned further away from the projection screen 1830 than the concave lens 1802, such that the collimated light beam is first focused and then diverges toward the projection screen 1830.

When the display zero-order light beam 1824 exits the display 1610, it is collimated. Therefore, when the display zero-order light beam 1824 passes through the concave lens 1802, it is diverged by the concave lens 1802, as illustrated in Figure 18. Consequently, the power density of the diverged display zero-order light beam 1824 is reduced or diluted across the diverged beam region compared to the power density of the original collimated input light beam 1820.

According to the second technique, the hologram (or its respective phase) modulating the display elements of the display 1610 can be pre-configured so that the diffracted primary light beam 1822 converges as it exits the display 1610. The degree of convergence is configured to correspond to the degree of divergence of the concave lens 1802; that is, the divergence of the concave lens is compensated for by the configured convergence. Thus, when the converged diffracted primary light beam 1822 passes through the concave lens 1802, the diffracted primary light beam 1822 is collimated to form a reconstructed holographic scene 1832 on the projection screen 1830, which is the same as without the pre-configuration of the hologram and the concave lens 1802. Thus, the reconstructed holographic scene 1832 has the same power density as the collimated input light beam 1820. In contrast, the display zero-order light beam 1834 diverges and smears (or is diluted) across the projection screen 1830 with reduced power density. The projection screen 1830 is positioned at a specified distance, for example, 50 cm, from the display 1610. The display's zero-order light beam 1834 can appear dark, like background noise in the holographic scene 1832. In this manner, the light suppression efficiency can be increased, for example, to over 99%, thereby increasing the signal-to-noise ratio of the holographic scene 1832.

In some implementations, the hologram is pre-configured by adding a corresponding phase to each phase of the display elements of the display 1610. Each phase of the display elements may be a phase adjusted according to the first technique—phase calibration. The corresponding phase for each of the display elements is:
It is expressed as follows:
During the ceremony,
λ represents the corresponding phase for the display element, λ represents the wavelength of the input light 1820, f represents the focal length of the optical divergent component (e.g., concave lens 1802), x and y represent the coordinates of the display element in the 2D display coordinate system, and a and b represent constants. The pair of values (a, b) can be adjusted based on applications, for example, to introduce astigmatism to people whose eyes suffer from astigmatism. When a is the same as b, for example a=1 and b=1, the defocus effect of the corresponding phase is circular; when a is different from b, for example a=1 and b=0.5, the defocus effect is elliptical and can be matched to a 2:1 anamorphic focal lens. When a=0 or b=0 but not both, the defocus effect produces a line focus rather than a regional focus and can be matched to a cylindrical focal lens.

In some implementations, the hologram is pre-configured by adding a virtual lens of a constituent cone when designing (or simulating) a holographic scene in a 3D software application such as Unity, for example, application 106 in Figure 1A. The constituent cone is described in more detail in Figures 20A-20B. The diffracted primary light beam 1822 forms a reconstructed cone with a field of view, and the constituent cone corresponds to the reconstructed cone and has the same apex angle as the field of view. In the simulation, the constituent cone can be moved relative to the display in the global 3D coordinate system along a direction perpendicular to the display, with a distance corresponding to the focal length of the optically divergent components. The constituent cone can be moved only once for all objects within the reconstructed cone. Holographic data, such as a primitive list of objects, is then generated based on the moved constituent cone in the global 3D coordinate system.

Third Technique – Zero-Order Light Deviation As explained above in Figures 16 and 17A–17B, the reconstruction cone of the holographic scene (or holographic content) has a field of view depending on the wavelength of the display and the input light beam. If the zero-order light of the display can deviate outside the reconstruction cone, the holographic scene can be observed without the zero-order light of the display.

Figure 19A illustrates a system 1900 that exemplifies the zero-order optics of the display in a holographic scene when the display 1610 is illuminated with input light 1920 that is collimated at 0° _{perpendicular} incidence. The optical device 1910 couples the collimated input light 1920 to illuminate the display 1610 at 0° incidence. In some implementations, as illustrated in Figure 19A, the optical device 1910 is a waveguide device 588 of Figure 5G, which includes an in-coupler 1916 and an out-coupler 1914 formed on a substrate 1912.

A first portion of the input light 1920 is incident on the display element of the hologram-modulated display 1610, diffracted by the display element, and becomes diffracted primary light 1922. A second portion of the input light 1920 is incident on the gap of the display 1610, reflected in the gap, and becomes at least a portion of the display zero-order light 1924. The diffracted primary light 1922 propagates in space to form a reconstruction cone with a field of view, e.g., 10°. Since the angle of incidence, e.g., 0°, is less than half of the field of view, e.g., 5°, the display zero-order light 1924 propagating with the same angle of reflection as the angle of incidence, e.g., 0°, is within the reconstruction cone. As illustrated in Figure 19A, the diffracted primary light 1922 forms a holographic scene 1932 on a two-dimensional (2D) projection screen 1930. The display zero-order light 1924 appears as collimated zero-order light 1934, as an undesirable image within the holographic scene 1932.

Figure 19B illustrates an example 1950 in which the zero-order display light is suppressed in a holographic scene displayed on the projection screen 1930 by inducing (or diverting) the zero-order display light from the holographic scene. Unlike the optical device 1910, the optical device 1960, which includes an in-coupler 1966 and an out-coupler 1964 formed on the substrate 1962, is configured to couple the collimated input light 1920 to illuminate the display 1610 at an incident angle _θi greater than 0°. Due to reflection, the zero-order display light 1974 exits the display 1610 at a reflection angle _θr that is the same as the incident angle _θi .

According to the third technique, the hologram (or their respective phases) modulating the display elements of the display 1610 can be pre-configured so that the diffracted primary light 1972 exits the display 1610 with perpendicular incidence. That is, deviations in the angle of incidence are compensated for by the configured hologram. Thus, the diffracted primary light beam 1972 forms a reconstructed cone that appears as a reconstructed holographic scene 1976 on the projection screen 1930, just as when the angle of incidence is perpendicular. If the angle of incidence, for example 6°, is greater than half the field of view of the reconstructed cone, for example 5°, the display zero-order light 1974 can deviate from or shift away from the reconstructed cone. Thus, as illustrated in Figure 19B, the shifted display zero-order image 1978 formed by the display zero-order light 1974 may be outside the holographic scene 1976 on the projection screen 1930. Similarly, as illustrated in Figure 19C, when viewed by viewer 1990, the display zero-order spot 1994 formed by the display zero-order light 1974 may be outside the holographic scene 1992 formed by the diffracted primary light 1972 to the viewer 1990's eye. By configuring the direction of the angle of incidence, the display zero-order light can be shifted vertically or horizontally in space.

In some implementations, the hologram is pre-configured by adding a corresponding phase to each phase of the display elements of the display 1610. Each phase of the display elements may be a phase adjusted according to the first technique—phase calibration. The corresponding phase for each of the display elements is:
It is expressed as follows:
During the ceremony,
θ represents the corresponding phase for the display element, λ represents the wavelength of the input light 1920, x and y represent the coordinates of the display element in the 2D display coordinate system (or 3D coordinate system), and θ represents the angle corresponding to the incident angle _θi , for example, θ = _θi .

In some implementations, the hologram is pre-configured by adding a virtual prism of a cone when designing (or simulating) the holographic scene in a 3D software application such as Unity, for example, application 106 in Figure 1A.

Figure 20A shows an example 2000 of a configuration cone 2020 and a reconstructed cone 2030 for a display 2002 and an optical device 2010 in a 3D coordinate system of a 3D software application. The optical device 2010 may be a light device, such as the optical diffraction device 598 in Figure 5H, which includes a grating 2014 formed on a substrate 2012.

As illustrated in Figure 20A, the optical device 2010 couples light 2040 to illuminate the display 2002 at an incidence angle greater than 0° rather than perpendicular incidence, which is effectively equivalent to rotating the configuration cone 2020 (along with all objects, including object 2022 within the configuration cone 2020) by an angle corresponding to (e.g., the same as) the reflection angle of the incidence angle relative to the 3D coordinate system. In some implementations, the configuration cone 2020 is rotated in the original 3D coordinate system. In some implementations, the original 3D coordinate system is rotated, but the configuration cone 2020 is not. Once the configuration cone 2020 is set in the 3D coordinate system, objects can be placed on the configuration cone 2020 without individually modifying the vertices of primitives. Thus, the simulated reconstructed cone 2030 (having all reconstructed objects, including reconstructed object 2032) and the display zero-order light 2042 are rotated relative to the display 2002 by the same reflection angle relative to the 3D coordinate system. In other words, the zero-order light 2042 of the display can appear in the holographic scene when viewed by the viewer.

Figure 20B illustrates Example 2050, in which the configuration cone 2020 of Figure 20A is adjusted to construct a hologram corresponding to a holographic scene in the 3D coordinate system of a 3D software application. The configuration cone 2020 (along with the designed objects, including object 2022) can be rotated by a rotation angle relative to the surface of the display 2002 in the 3D coordinate system. The rotation angle corresponds to the angle of incidence (e.g., identical) such that the adjusted configuration cone 2060 (having the adjusted designed objects, including the adjusted object 2062) is perpendicularly incident to the display 2002. The configuration cone 2020 can be adjusted only once for all the designed objects. Holographic data, e.g., a primitive list of objects, is then generated based on the adjusted configuration cone 2060 in the global 3D coordinate system. The hologram is then generated based on the holographic data.

Therefore, when the optical device 2010 combines the input light 2040 and illuminates the display 2002 at the angle of incidence, the first portion of the input light 2040 is diffracted by the display elements modulated with a pre-configured hologram. The diffracted primary light forms a reconstructed cone 2070 perpendicular to the display 2002 (having a reconstructed object including the reconstructed object 2072 of the designed object 2062). The reconstructed cone 2070 has a viewing angle _θv . In contrast, the second portion of the input light 2040 is reflected in the gap without modulation of the pre-configured hologram, becoming the display zero-order light 2042 that exits the display at the same reflection angle _θr as the angle of incidence _θi . Therefore, when the angle of incidence _θi is greater than half the viewing angle, i.e., _θi > _θv /2, the display zero-order light 2042 is outside the reconstructed cone 2070 and thus outside the holographic scene as seen by the viewer.

The input light 2040 can be coupled to the optical device 2010 in any preferred manner, for example, by an in-coupler such as the in-coupler 1966 in Figure 19B, by a prism as illustrated in Figure 21, or by a wedge-shaped substrate as illustrated in Figure 22.

Figure 21 illustrates an example 2100 in which collimated input light 2120 is coupled to an optical device 2110 via a coupling prism 2111 to illuminate the display 1610 at an incident angle that suppresses zero-order display light in a holographic scene. The optical device 2110 includes a grating 2114 on a substrate 2112. The coupling prism 2111 couples the input light 2120 to the substrate 2112, which guides the input light 2120 toward the grating 2114. The grating 2114 diffracts the input light 2120 toward the display 1610 at an outward incident angle. The hologram is pre-configured so that the diffracted primary light 2122 exits the display 1610, surrounding the perpendicularly incident light to form a reconstruction cone, while the zero-order display light 2124 exits the display 1610 at the same reflection angle as the incident angle. If the angle of incidence is greater than half the field of view of the reconstruction cone, the display zero-order light 2124 forms a shifted zero-order spot 2134 outside the holographic scene 2132 when viewed by the viewer 2130.

Figure 22 illustrates an exemplary system 2200 that couples light via a wedge-shaped substrate 2212 of an optical device 2210 to illuminate the display 1610 at an incident angle that suppresses zero-order display light in a holographic scene. The optical device 2210 includes a grating 2214 on the wedge-shaped substrate 2212. The wedge-shaped substrate 2212 couples input light 2220 to the substrate 2212, which guides input light 2120 toward the grating 2214. The grating 2214 diffracts the input light 2120 outward toward the display 1610 at an incident angle. The hologram is pre-configured so that diffracted primary light 2222 exits the display 1610, surrounding the perpendicularly incident light to form a reconstruction cone, while zero-order display light 2224 exits the display 1610 at the same reflection angle as the incident angle. If the angle of incidence is greater than half the field of view of the reconstruction cone, the display zero-order light 2224 forms a shifted zero-order spot 2234 outside the holographic scene 2232 when viewed by the viewer 2230.

According to the third technique, the zero-order light emitted from the display has a larger deviation angle than the diffracted primary light emitted from the display. Therefore, as further explained in the fourth technique, "zero-order light blocking," and the fifth technique, "zero-order light redirection," for example, the zero-order light can be suppressed (or eliminated) in the holographic scene based on the angular difference.

Fourth Technique – Zero-Order Light Blocking Figures 23A–23B illustrate exemplary systems 2300, 2350 that suppress display zero-order light in a holographic scene by blocking or absorbing display zero-order light reflected from the display by optical blocking components. The optical blocking components may be any preferred structure, e.g., a louver layer, a metamaterial layer, a metamaterial structure, a metasurface, or any other type of engineered microstructure or nanostructure that can exhibit blocking properties.

For illustrative purposes, similar to Figure 21, the coupling prism 2311 couples the collimated input light 2320 to an optical device 2310 having a grating 2314 formed on a substrate 2312. The grating 2314 is configured to diffract the input light 2320 outward, illuminating the display 1610 at a certain angle of incidence, for example, an angle greater than half the viewing angle of the reconstruction cone. By applying a third technique, the hologram is pre-configured such that the diffracted primary light 2322 exits the display 1610 in the same way as if the input light were incident on the display 1610 in perpendicular incidence, while the display zero-order light 2324 propagates away from the display 1610 at the same reflection angle as the angle of incidence.

The metamaterial layer 2316 is formed on the substrate 2312 as an example of an optical blocking component (e.g., deposited on or attached to it). As illustrated in Figures 23A-23B, the metamaterial layer 2316 and the grid 2314 can be formed on both sides of the substrate 2312. The metamaterial layer 2316 can be fabricated as an array of microstructures or nanostructures smaller than the wavelength of interest. By individually and collectively configuring the geometry of the microstructures or nanostructures, the metamaterial layer 2316 can be designed to interact with light in a desired manner. In this disclosure, the metamaterial layer 2316 is configured to transmit light beams having an angle smaller than a predetermined angle and to block light beams having an angle larger than a predetermined angle. The predetermined angle can be set to be smaller than the angle of incidence and greater than half the field of view of the reconstructed cone formed by the diffracted primary light 2322. Therefore, the diffracted primary light 2322 can be transmitted through the metamaterial layer 2316 with a transmission efficiency of, for example, 50%, 60%, 70%, 80%, 90%, or 99% or higher. In contrast, the zero-order display light can be blocked or absorbed by the metamaterial layer 2316 with, for example, a blocking efficiency of 100%.

The light suppression efficiency of display zero-order light in a holographic scene can be 100%. As illustrated in Figure 23A, the diffracted primary light 2322 can form a holographic scene 2332 on the projection screen 2330 that is free of display zero-order light 2324. As illustrated in Figure 23B, when viewed by the viewer 2360, the diffracted primary light 2322 can form a holographic scene 2362 for the viewer's eye that is free of display zero-order light 2324.

Fifth Technique – Zero-Order Light Redirection Figure 24 illustrates a system 2400 that suppresses zero-order display light in a holographic scene by redirecting zero-order display light away from the holographic scene via an optical redirection structure. The optical redirection structure may be a grating, such as a holographic grating like a Bragg grating, or any other suitable redirection structure.

Similar to system 590 in Figure 5H, system 2400 includes a computer 2401 (e.g., computer 591 in Figure 5H), a controller 2402 (e.g., controller 592 in Figure 5H), a reflective display 2404 (e.g., reflective display 594 in Figure 5H), and an irradiator 2406 (e.g., irradiator 596 in Figure 5H). System 2400 also includes an optical device 2410 which may include optical diffraction devices such as optical diffraction device 598 in Figure 5H, 598A in Figure 5I, 598B in Figure 5J, or 598C in Figure 5K, optical diffraction device 900 in Figures 9A and 9B, 1000 in Figures 10A and 10B, 1100 in Figure 11, 1200 in Figure 12A, 1250 in Figure 12B, or 1270 in Figure 12C, or 1500 in Figure 15. In some implementations, as illustrated in Figure 24, the optical device 2410 includes a transmission field grating structure 2414 as an optical diffraction device on a substrate 2412 (e.g., substrate 598-2 in Figure 5H). The transmission field grating structure 2414 may be field grating structure 598-1 in Figure 5H. The transmission field grating structure 2414 may include one or more gratings for one or more different colors of light. The substrate 2412 may be a transparent glass substrate.

Similar to the above, the optical device 2410 can be positioned adjacent to the front of the display 2404. In some implementations, the top surface of the optical device 2410 (e.g., the surface of the field grid structure 2414) is attached to the front of the display 2404, for example, through an exponentially matched material. In some implementations, an air gap exists between the top surface of the optical device 2410 and the display 2404. In some implementations, a spacer, such as glass, is inserted into the air gap between the top surface of the optical device 2410 and the display 2404. To better illustrate light propagation, the air gap is used as an example in Figure 24 and Figures 26A-33 below.

The controller 2402 is configured to receive graphic data corresponding to one or more objects from the computer 591 (for example, by using a 3D software application such as Unity), perform calculations on the graphic data, generate control signals for modulation, and transmit them to the display 2404 through the memory buffer 2403. The controller 2402 is also coupled to the irradiator 2406 and is configured to provide a timing signal 2405 to actuate the irradiator 2406 to provide input light 2420. The input light 2420 is then diffracted by the transmission field grating 2414 of the optical device 2410 to illuminate the display 2404. The first portion of the input light 2420 incident on the display elements of the display 2404 is diffracted by the display 2404, and the diffracted primary light 2421 forms a holographic light field 2422 toward the viewer. The holographic light field 2422 can correspond to a reconstructed cone (or frustum of a cone) with a viewing angle. The display 2404 may include a rearview mirror on its back, which can reflect light toward the viewer. A second portion of the input light 2420 entering the gap of the display 2404 is reflected by the display 2404, for example by the rearview mirror, to become the zero-order display light 2424.

As described above, the transmission field grating 2414 can be configured to diffract the input light 2420 outward from the irradiator 2406, illuminating the display 2404 off-axis at a certain incident angle, for example, an angle greater than half the viewing angle of the reconstruction cone (or frustum of a cone). By applying a third technique, the diffracted primary light 2421 exits the display 2404 in the same manner as when the input light 2420 is incident perpendicularly on the axis, while the display zero-order light 2424 exits at a reflection angle that is the same as the incident angle outside the reconstruction cone.

As illustrated in Figure 24, the system 2400 may include an optical redirection structure 2416 configured to diffract a first light beam having the same angle as a predetermined angle at a certain diffraction angle, with substantially greater diffraction efficiency than a second light beam having a different angle than a predetermined angle. The optical redirection structure 2416 may be a holographic grating such as a Bragg grating. The diffraction angle can be substantially larger than the predetermined angle. In some implementations, the optical redirection structure 2416 includes one or more gratings for one or more different colors of light, as further illustrated in Figures 30A-33. In some implementations, the optical redirection structure 2416 is located downstream of the optical device 2410, away from the display 2404. In some implementations, as illustrated in Figure 24, the optical redirection structure 2416 is formed on the side of the substrate 2412 opposite to the transmission field grating structure 2414.

According to the fifth technique, the optical redirection structure 2416 can be configured to have a predetermined angle identical to the reflection angle of the display zero-order light 2424 or the incident angle of the input light 2420 in the display 2404. When the display zero-order light 2424 propagates at the reflection angle, the optical redirection structure 2416 can diffract the display zero-order light 2424 at the diffraction angle with substantially greater diffraction efficiency than the diffracted primary light 2421, while the diffracted primary light 2421 can pass through the optical redirection structure 2416 to form the holographic light field 2422. In this way, the optical redirection structure 2416 can redirect the display zero-order light 2424 further away from the holographic light field 2422.

Figures 25A–25C illustrate an example of redirecting zero-order display light in different directions in space via zero-order redirection gratings 2500, 2530, and 2550 shown in Figures 25A, 25B, and 25C. The zero-order redirection gratings 2500, 2530, and 2550 can be located within the optical redirection grating structure 2416 shown in Figure 24. The redirection gratings 2500, 2530, and 2550 can be manufactured according to the method illustrated in Figure 7A.

For comparison, the display zero-order light 2502 is incident on the zero-order redirection gratings 2500, 2530, and 2550 at an incident angle of -6.0°, which is a predetermined angle relative to the redirection gratings 2500, 2530, and 2550. The redirection gratings 2500, 2530, and 2550 are configured to diffract the display zero-order light 2502 with high diffraction efficiency at a diffraction angle substantially larger than the incident angle of the display zero-order light 2502. The redirection gratings 2500, 2530, and 2550 can be configured to diffract the display zero-order light 2502 at different diffraction angles, for example, 60° for grating 2500 shown in Figure 25A, 56° for grating 2530 shown in Figure 25B, and -56° for grating 2550 shown in Figure 25C.

Figures 26A–26E illustrate an example of redirecting zero-order light for a display when light enters in different directions in space through an optical redirection structure (e.g., a zero-order redirection grating) at different angles of incidence. Each of the angles of incidence, for example, -6° or 6° in air, is configured to be greater than half the viewing angle of the reconstruction cone corresponding to the holographic light field, for example, 5° in air.

As illustrated in Figure 26A, the system 2600 includes an optical device 2610, which may be the optical device 2410 of Figure 24. The optical device 2610 includes a substrate 2612 (e.g., the substrate 2412 of Figure 24), a transmission field grating structure 2614 (e.g., the transmission field grating structure 2414 of Figure 24), and a zero-order redirection grating structure 2616 (e.g., the zero-order redirection grating structure 2416 of Figure 24). The optical device 2610 may include a cover glass 2618 on the zero-order redirection grating structure 2616.

The input light 2620 from the irradiator 2406 is diffracted by the transmission field grating structure 2614 to irradiate the display 2404 at an incident angle of -6° (in air). The first portion of the input light 2620 that irradiates the modulated display elements of the display 2404 is diffracted to pass through the optical device 2610 (including the zero-order redirection grating structure 2616) to become diffracted primary light 2621 that forms the holographic light field 2622. The second portion of the input light 2620 that irradiates the gap of the display 2404 is reflected to exit the display 2404 as display zero-order light 2624. The display zero-order light 2624 is redirected by the zero-order redirection grating structure 2616 at a diffraction angle substantially larger than the incident angle, for example, -28° in the glass. Due to Fresnel reflection, a portion of the redirected display zero-order light is reflected backward to the optical device 2610 by the interface between the cover glass 2618 and the air. The Fresnel reflection of the reflected display zero-order light, e.g., zero-order light 2625, can be absorbed by a light absorber 2619 formed on the edge of the optical device 2610. The light absorber 2619 may be similar to the light absorber 1104 in Figure 11, 1204 in Figures 12A and 12C, or 1254 in Figure 12B. Another portion of the redirected display zero-order light, far from the holographic light field 2622, is transmitted downward through the interface into the air at a redirection angle of -45°, e.g., redirected zero-order light 2626.

As illustrated in Figure 26B, system 2630 includes an optical device 2640, which may be the optical device 2410 in Figure 24. The optical device 2640 includes a substrate 2642 (e.g., substrate 2412 in Figure 24), a transmission field grating structure 2644 (e.g., transmission field grating structure 2414 in Figure 24), and a zero-order redirection grating structure 2646 (e.g., zero-order redirection grating structure 2416 in Figure 24). The optical device 2640 may include a cover glass 2648 on the zero-order redirection grating structure 2646.

Unlike the transmission field lattice structure 2614 of the optical device 2610 in Figure 26A, the transmission field lattice structure 2644 of the optical device 2640 diffracts the input light 2620 from the irradiator 2406 to irradiate the display 2404 at an incident angle of +6° (in air). The first portion of the input light 2620 that irradiates onto the modulated display elements of the display 2404 is diffracted to pass through the optical device 2640 (including the zero-order redirection lattice structure 2646) to become diffracted primary light 2631 that forms the holographic light field 2632. The second portion of the input light 2620 that irradiates onto the gap of the display 2404 is reflected to exit the display 2404 as display zero-order light 2634. Unlike the zero-order redirection lattice structure 2616 in Figure 26A, the zero-order redirection lattice structure 2646 redirects (or diffracts) the display zero-order light 2624 at a diffraction angle substantially larger than the incident angle, e.g., +28° within the glass. Due to Fresnel reflection, a portion of the redirected display zero-order light is reflected backward to the optical device 2610 by the interface between the cover glass 2618 and the air, and the Fresnel reflection of the reflected display zero-order light, e.g., zero-order light 2635, can be absorbed by a light absorber 2649 formed on the edge of the optical device 2640. The light absorber 2649 may be similar to the light absorber 2619 in Figure 26A. Another portion of the redirected display zero-order light, far from the holographic light field 2622, is transmitted upward through the interface into the air at a redirection angle of +45°, e.g., the redirected zero-order light 2636.

As illustrated in Figure 26C, system 2650 includes an optical device 2660, which may be the optical device 2410 in Figure 24. The optical device 2660 includes a substrate 2662 (e.g., substrate 2412 in Figure 24), a transmission field grating structure 2664 (e.g., transmission field grating structure 2414 in Figure 24), and a zero-order redirection grating structure 2666 (e.g., zero-order redirection grating structure 2416 in Figure 24). The optical device 2660 may include a cover glass 2668 on the zero-order redirection grating structure 2666.

Similar to the transmission field lattice structure 2614 of the optical device 2610 in Figure 26A, the transmission field lattice structure 2664 of the optical device 2660 diffracts the input light 2620 from the irradiator 2406 to irradiate the display 2404 at an incident angle of -6° (in air). The first portion of the input light 2620 that irradiates the modulated display elements of the display 2404 is diffracted to pass through the optical device 2660 (including the zero-order redirection lattice structure 2666) to become diffracted primary light 2631 that forms the holographic light field 2632. The second portion of the input light 2620 that irradiates the gap of the display 2404 is reflected to exit the display 2404 to become at least a portion of the display zero-order light 2654. Unlike the zero-order redirection lattice structure 2616 in Figure 26A, the zero-order redirection lattice structure 2666 redirects (or diffracts) the display zero-order light 2654 at a diffraction angle substantially larger than the incident angle, e.g., +28° within the glass. Due to Fresnel reflection, a portion of the redirected display zero-order light is reflected backward to the optical device 2660 by the interface between the cover glass 2668 and the air, and the Fresnel reflection of the reflected display zero-order light, e.g., zero-order light 2655, can be absorbed by a light absorber 2649 formed on the edge of the optical device 2640. The light absorber 2669 may be the light absorber 2619 in Figure 26A. Another portion of the redirected display zero-order light, far from the holographic light field 2622, is transmitted upward through the interface into the air at a redirection angle of +45°, e.g., the redirected zero-order light 2656.

To eliminate the effect of Fresnel reflection on redirected zero-order display light at the interface between the cover glass surface and the air, an anti-reflective (AR) coating can be formed on the surface of the cover glass 2668. Thus, the redirected zero-order display light can be transmitted into the air with high transmittance, while there is little to no back reflection to the optical device.

As illustrated in Figure 26D, system 2670 includes an optical device 2680. Similar to the optical device 2660 in Figure 26C, the optical device 2680 is configured to diffract input light 2620 to illuminate the display 2404 at an incident angle of -6° (in air), and to redirect the display zero-order light 2654 upward into the air at a redirection angle of +45°. However, unlike the optical device 2660 in Figure 26C, the optical device 2680 includes an AR coating layer 2682 formed on the outer surface of the cover glass 2668. Therefore, the redirected display zero-order light, for example, the redirected zero-order light 2672, is transmitted substantially into the air through the cover glass 2668 at a redirection angle of +45°. In such a manner, there is little to no Fresnel reflection of the redirected zero-order light returning to the optical device 2680.

Figure 26E shows another example of redirecting the zero-order light of the display at a larger redirection angle, e.g., +75° in air or approximately +40° in glass. As illustrated in Figure 26E, system 2690 includes an optical device 2692. Similar to the optical device 2660 in Figure 26C, the optical device 2692 is configured to diffract the input light 2620 to illuminate the display 2404 at an incident angle of -6° (in air). However, unlike the optical device 2660 in Figure 26C, the optical device 2692 includes a zero-order redirection lattice structure 2694 configured to redirect the zero-order light 2654 upward into air at a redirection angle of +75°, e.g., to the redirected zero-order light 2696. Thus, there is a larger Fresnel reflection of the zero-order light 2698 returning into the optical device 2692, which can be absorbed by the light absorber 2669.

When p-polarized light is incident at a Brewster angle at the interface between a medium with a higher refractive index and a medium with a lower refractive index, there is no Fresnel reflection for p-polarized light.

Figure 27A illustrates an exemplary system 2700 that redirects p-polarized zero-order display light to transmit it into air at the Blue Star angle. System 2700 includes an optical device 2710, which may be the optical device 2410 shown in Figure 24. The optical device 2710 includes a substrate 2712 (e.g., the substrate 2412 in Figure 24), a transmission field lattice structure 2714 (e.g., the transmission field lattice structure 2414 in Figure 24), and a zero-order redirection lattice structure 2716 (e.g., the zero-order redirection lattice structure 2416 in Figure 24). The optical device 2710 may include a cover glass 2718 on the zero-order redirection lattice structure 2716.

Similar to the transmission field lattice structure 2614 of the optical device 2610 in Figure 26A, the transmission field lattice structure 2714 of the optical device 2710 diffracts the input light 2620 from the irradiator 2406 to irradiate the display 2404 at an incident angle of -6° (in air). The first portion of the input light 2620 irradiating onto the modulated display elements of the display 2404 is diffracted to pass through the optical device 2710 (including the zero-order redirection lattice structure 2716) to become diffracted primary light 2701, forming the holographic light field 2702. The second portion of the input light 2620 irradiating onto the gap of the display 2404 is reflected to exit the display 2404 as display zero-order light 2704. Display zero-order light 2704 can have a p-polarized state. In some cases, the input light 2620 from the irradiator 2406 has a p-polarized state. In some cases, the optical device 2710 includes one or more optical polarizing devices (e.g., polarizers, retarders, waveplates, or combinations thereof) configured to control the polarization state of the diffracted input light 2620 to be p-polarized. In some implementations, the optical device 2710 includes an optical retarder (e.g., a broadband half-wave retarder) followed by an optical polarizer (e.g., a linear polarizer). The optical retarder is configured, for example, to rotate the light of each color from s-polarized to p-polarized with a corresponding efficiency, and the optical polarizer is configured to absorb any proportion of the light of each color that has not been rotated from s-polarized to p-polarized.

Unlike the zero-order redirection lattice structure 2616 in Figure 26A, the zero-order redirection lattice structure 2716 redirects (or diffracts) the display zero-order light 2654 at the interface between the cover glass 2718 and the air at a Blue Star angle, for example, approximately -37° within the glass. Therefore, there is no Fresnel reflection of the redirected display zero-order light returning to the optical device 2710, and almost all of the redirected display zero-order light is transmitted into the air at a Blue Star angle of approximately -57°, for example, as redirected zero-order light 2706.

Figures 27B-27C illustrate an example of redirecting s-polarized zero-order display light using an optical polarization device such as an optical retarder for transmission at the Brewster angle. When the zero-order display light exits the display 2404 with s-polarization, the optical device can include an optical retarder before the interface to the air. The optical retarder can convert the polarization state of the zero-order display light from s-polarized to p-polarized to transmit at the Brewster angle at the air interface without Fresnel reflection.

As illustrated in Figure 27B, system 2730 includes an optical device 2740, which may be the optical device 2410 in Figure 24. The optical device 2740 includes a substrate 2742 (e.g., substrate 2412 in Figure 24), a transmission field grating structure 2744 (e.g., transmission field grating structure 2414 in Figure 24), and a zero-order redirection grating structure 2746 (e.g., zero-order redirection grating structure 2416 in Figure 24). The optical device 2740 may include a cover glass 2748 on the zero-order redirection grating structure 2746.

Similar to the transmission field lattice structure 2714 of the optical device 2710 in Figure 27A, the transmission field lattice structure 2744 of the optical device 2740 diffracts the input light 2620 from the irradiator 2406 to irradiate the display 2404 at an incident angle of -6° (in air). The first portion of the input light 2620 that irradiates the modulated display elements of the display 2404 is diffracted to pass through the optical device 2740 (including the zero-order redirection lattice structure 2746) to become diffracted primary light 2731 that forms a holographic light field 2732. The second portion of the input light 2620 that irradiates the gap of the display 2404 is reflected to exit the display 2404 as display zero-order light 2734. Unlike the display zero-order light 2704 in Figure 27A, the display zero-order light 2734 can have s-polarization. In some cases, the input light 2620 from the irradiator 2406 has an s-polarization state. In some cases, the optical device 2740 includes one or more optical polarizing devices configured to control the polarization state of the diffracted input light 2620 to be s-polarized.

Unlike the optical device 2710 in Figure 27A, the optical device 2740 includes an optical retarder 2747 configured to convert the polarization state of the display's zero-order light 2734 from s-polarization to p-polarization. In some examples, the polarization conversion can be achieved using a broadband half-wavelength retarder that can rotate the light of each color from s-polarization to p-polarization with different efficiencies for each color. Following the half-wavelength retarder is a "cleanup" linear polarizer to absorb the proportion of light of each color that has not been rotated from s-polarization to p-polarization. In this way, the retarder can rotate the polarization of the light emanating from the optical device 2740 to another polarization more suitable for the best performance of the display 2404, and the linear polarizer can remove light incident on the display 2404 in polarizations that are less suitable for the best performance of the display 2404.

In some implementations, as illustrated in Figure 27B, the optical retarder 2747 (and optionally, a linear polarizer) is positioned in front of the zero-order redirection grid structure 2746 on the substrate 2742. Similar to the zero-order redirection grid structure 2716 in Figure 27A, the zero-order redirection grid structure 2746 redirects (or diffracts) the display zero-order light 2734, which has p-polarization at a Blue Star angle, e.g., approximately -37° within the glass, at the interface between the cover glass 2748 and the air. Therefore, there is no or negligible Fresnel reflection of the redirected display zero-order light returning to the optical device 2740, and almost all of the redirected display zero-order light is transmitted into the air at a Blue Star angle of approximately -57°, e.g., the redirected zero-order light 2736.

In some implementations, as illustrated in Figure 27C, in the optical device 2760 of system 2750, the optical retarder 2747 is positioned after the zero-order redirection lattice structure 2746 relative to the substrate 2742. The zero-order redirection lattice structure 2746 is positioned between the substrate 2742 and the lattice cover glass 2748. The optical retarder 2747 can be positioned between the lattice cover glass 2748 and the retarder cover glass 2762. Similar to the zero-order redirection lattice structure 2716 in Figure 27A, the zero-order redirection lattice structure 2746 redirects (or diffracts) the display zero-order light 2734 at the interface between the cover glass 2762 and air at a Blue Star angle, for example, about -37° within the glass. Therefore, there is no or negligible Fresnel reflection of the redirected zero-order light of the display returning to the optical device 2760, and almost all of the redirected zero-order light of the display is transmitted into the air at a Blue Star angle of approximately -57°, for example, the redirected zero-order light 2752.

Figure 28 shows an exemplary system 2800 in which the display zero-order light is redirected to an anisotropic transmitter 2820 to absorb the redirected display zero-order light. The anisotropic transmitter 2820 is configured to transmit a first light beam (e.g., diffracted primary light) at an angle smaller than a predetermined angle (e.g., less than half the field of view of the reconstruction cone) and absorb a second light beam (e.g., redirected display zero-order light) at an angle larger than a predetermined angle (e.g., the redirection angle). The predetermined angle is configured to be greater than half the field of view and smaller than the redirection angle at which the display zero-order light is diffracted by the optical redirection component.

System 2800 includes an optical device 2810, which may include the optical device 2410 shown in Figure 24. The optical device 2810 includes a substrate 2812 (e.g., the substrate 2412 in Figure 24), a transmission field grating structure 2814 (e.g., the transmission field grating structure 2414 in Figure 24), and a zero-order redirection grating structure 2816 (e.g., the zero-order redirection grating structure 2416 in Figure 24). The optical device 2810 may include a cover glass 2818 on the zero-order redirection grating structure 2816.

Similar to the transmission field lattice structure 2414 of the optical device 2410 in Figure 24, the transmission field lattice structure 2814 of the optical device 2810 diffracts the input light 2620 from the irradiator 2406 to irradiate the display 2404 at an incident angle of -6° (in air). The first portion of the input light 2620 that irradiates the modulated display elements of the display 2404 is diffracted to pass through the optical device 2810 (including the zero-order redirection lattice structure 2816) to become diffracted primary light 2801 that forms the holographic light field 2802. The incident angle is configured to be greater than half the viewing angle of the reconstructed cone corresponding to the holographic light field 2802. The second portion of the input light 2620 that irradiates the gap of the display 2404 is reflected so that it exits the display 2404 as at least part of the display zero-order light 2804. Similar to the zero-order redirection lattice structure 2416 in Figure 24, the zero-order redirection lattice structure 2816 redirects (or diffracts) the display zero-order light 2804 at a redirection angle substantially larger than the angle of incidence, for example, an angle corresponding to approximately 75° in air.

Unlike the optical diffraction structure 2410 in Figure 24, the optical device 2810 may include an anisotropic transmitter 2820 configured to transmit the diffracted primary light 2801 and absorb the display zero-order light 2804. In some examples, the anisotropic transmitter 2820 includes a louver film configured to have about ±30° in air or about ±20° in acrylic. The anisotropic transmitter 2820 substantially transmits the diffracted primary light 2801, for example, about ±5° in air (about ±3° in acrylic), and absorbs the display zero-order light 2804, for example, about 75° in air. The anisotropic transmitter 2820 can be indexed to the cover glass 2818 so that there is no significant Fresnel reflection returning from the surface of the anisotropic transmitter 2820 to the optical device 2810 for the display zero-order light 2804 having either an s-polarized or p-polarized state. The louvers within the louver film can also be adjusted to match the index of the permeable material of the louver film, thereby eliminating Fresnel reflection from the louvers.

In the previous examples shown in Figures 26A–26E, 27A–27B, and Figure 28, the zero-order redirection lattice structure is configured to diffract the zero-order display light at a redirection angle smaller than the critical angle for total internal reflection at the interface with air.

Figure 29 illustrates an exemplary system 2900 that redirects the zero-order light of a display to completely reflect the zero-order light of the display. Similar to the optical device 2610 in Figure 26A, the optical device 2910 of system 2900 includes a transmission field lattice structure 2914 formed on a substrate 2912 and configured to diffract input light 2620 to illuminate the display 2404 at incident angles, for example, -6° in air and approximately -4° in glass.

However, unlike the optical device 2610 in Figure 26A, the optical device 2910 includes a zero-order redirection lattice structure 2916 configured to redirect the display zero-order light 2904 at a redirection angle in the glass, e.g., about +60°, which is greater than the critical angle for total internal reflection in the glass, e.g., about 41°, for the transition from the cover glass 2918 to air at the high-low index interface 2919. Thus, the display zero-order light 2904 is completely reflected at the interface 2919, and the Fresnel reflection of the display zero-order light 2906 can be absorbed by a light absorber 2920 (e.g., the light absorber 2619 in Figure 26A) formed at the edge of the optical device 2910. In contrast, a portion of the input light 2620 illuminating the modulated display elements of the display 2404 is diffracted to pass through the optical device 2910 (including the zero-order redirection lattice structure 2916) to become diffracted first-order light 2901, which forms a holographic light field 2902 without the zero-order display light 2904.

The input light illuminating the display can include, for example, light of several different colors, such as red, green, and blue. Light of different colors can be incident sequentially on the display, and the corresponding holographic data (or holograms) of different colors can sequentially modulate the display elements of the display. As described above, an optical diffraction device, for example, the optical diffraction device 598 in Figure 5H, can be configured to diffract light of different colors to illuminate the display, and can also be configured to reduce color crosstalk between light of different colors. For example, the optical diffraction device 598 includes multiple holographic gratings for different colors in different recording layers, as illustrated, for example, in Figures 9A to 12C. In some examples, as described above with respect to Figures 9A to 10B, the optical diffraction device can include multiple holographic gratings having one or more color-selective polarizers to suppress (e.g., eliminate or minimize) color crosstalk. In some examples, as described above with respect to Figures 11 to 12C and 15, the optical diffraction device can include multiple holographic gratings having one or more reflective layers for light of different colors incident at each incident angle to suppress color crosstalk and zero-order light.

Similarly, optical redirection devices can also be configured to redirect display zero-order light of different colors away from the corresponding holographic scene, and can also be configured to reduce color crosstalk between display zero-order light of different colors by redirecting display zero-order light of different colors in different directions away from the holographic scene, for example, in a plane and/or space. Figures 30A-30B, 31A-31B, 32, and 33 illustrate different implementation examples.

Figures 30A-30B illustrate an example of redirecting zero-order display light of two different colors (e.g., blue and red) in different directions away from the holographic scene.

As illustrated in Figure 30A, similar to system 2400 in Figure 24, system 3000 includes a computer 2401 (e.g., computer 2401 in Figure 24), a controller 3002 (e.g., controller 2402 in Figure 24), a reflective display 3004 (e.g., reflective display 2404 in Figure 24), and an irradiator 3006 (e.g., irradiator 2406 in Figure 24). System 3000 also includes an optical device 3010, which may include an optical diffraction device, e.g., the optical diffraction device 900 in Figures 9A and 9B, or 1100 in Figure 11. In some implementations, as illustrated in Figure 30A, the optical device 3010 includes a transmission field grating structure 3014 on a substrate 3012 (e.g., substrate 2412 in Figure 24). The transmission field grating structure 3014 may include two corresponding different gratings for two different colors of light.

The controller 3002 is configured to receive graphic data corresponding to one or more objects from the computer 3001 (for example, by using a 3D software application such as Unity), perform calculations on the graphic data, generate control signals for modulation, and transmit them to the display 3004 through the memory buffer 3003. The controller 3002 is also coupled to the irradiator 3006 and is configured to provide a timing signal 3005 to actuate the irradiator 3006 to provide input light 3020. The input light 3020 is then diffracted by the transmission field grating structure 3014 of the optical device 3010 to irradiate the display 3004. The first portion of the input light 3020 incident on the display elements of the display 3004 is diffracted by the display 3004, and the diffracted primary light 3021 forms a holographic light field 3022 toward the viewer. The holographic light field 3022 can correspond to a reconstructed cone (or frustum of a cone) with a viewing angle. The second portion of the input light 3020 incident on the gap of the display 3004 is reflected by the display 3004 and becomes at least a portion of the display zero-order light 3024.

The transmission field lattice structure 3014 is configured to diffract input light 3020 of different colors outward from the irradiator 3006, illuminating the display 3004 off-axis at a certain incident angle greater than half the viewing angle of the reconstruction cone (or frustum of a cone), for example, -6° in air or about -4° in glass. By applying a third technique, the diffracted primary light 3021 exits the display 3004 in the same manner as when the input light 3020 is incident perpendicularly on the axis, while the display zero-order light 3024 exits at a reflection angle that is identical to the incident angle outside the reconstruction cone.

As illustrated in Figure 30A, the system 3000 may include an optical redirection structure having corresponding zero-order redirection gratings 3016 and 3018 for different colors of light (blue and red). Each zero-order redirection grating 3016, 3018 may be similar to the redirection grating 2416 in Figure 24 and can be configured to diffract a first light beam having the same angle as a given angle at a certain diffraction angle with substantially greater diffraction efficiency than a second light beam having a different angle. Each zero-order redirection grating 3016, 3018 may be a holographic grating, such as a Bragg grating, for the corresponding color of light.

As illustrated in Figure 30A, the zero-order redirection grating 3016 is configured to diffract the blue display zero-order light at a diffraction angle of +45° in air (approximately +28° in glass), for example, at the reflection angle (same as the incident angle) of the redirected blue display zero-order light 3026. The zero-order redirection grating 3018 is configured to diffract the red display zero-order light from approximately -6° in air (approximately -4° in glass) to approximately -45° (approximately -28° in glass), for example, to the redirected red display zero-order light 3028.

The zero-order redirection gratings 3016 and 3018 can be sequentially positioned on the substrate 3012 opposite the transmission field grating structure 3014. Since light with shorter wavelengths tends to crosstalk more strongly from gratings intended for longer wavelengths, the zero-order redirection grating 3016 for blue light can be positioned closer to the display than the zero-order redirection grating 3018 for red light. The two zero-order redirection gratings 3016 and 3018 can have substantially different fringe plane inclinations, which can reduce color crosstalk.

In some implementations, as illustrated in Figure 30A, each zero-order redirection grid 3016, 3018 for different colored light is recorded on a corresponding recording material, such as a photosensitive polymer, and protected by corresponding cover glasses 3017, 3019.

In some implementations, as illustrated in Figure 30B, each zero-order redirection grating 3046, 3048 of the optical device 3040 in system 3030 for different colored light is recorded on the same recording material, e.g., a photosensitive polymer, and protected by a cover glass 3047. Zero-order redirection grating 3046 may be the same as zero-order redirection grating 3016 and is configured to diffract blue display zero-order light from approximately -6° in air (approximately -4° in glass) to approximately +45° (approximately +28° in glass), for example, redirected blue display zero-order light 3036. Zero-order redirection grating 3048 may be the same as zero-order redirection grating 3018 and is configured to diffract red display zero-order light from approximately -6° in air (approximately -4° in glass) to approximately -45° (approximately -28° in glass), for example, redirected red display zero-order light 3038.

Optical devices 3010 and 3040 may include light absorbers on their edges (e.g., light absorber 2619 in Figure 26A) to reduce Fresnel reflection at the interface between the cover glass and air.

Figures 31A–31B illustrate exemplary systems 3100 and 3150 for redirecting zero-order display light of three different colors (blue, green, and red) in different directions away from a holographic scene within the same plane. Compared to systems for two different colors of light, the system for three different colors of light, as illustrated in Figure 30A or 30B, for example, includes an optical diffraction structure comprising three different diffraction gratings for diffracting the three color input light to illuminate the display at the same angle of incidence, and an optical redirection structure comprising three different zero-order redirection gratings for diffracting the three color display zero-order light in different directions at different diffraction angles.

As illustrated in Figure 31A, similar to system 3000 in Figure 30A, system 3100 includes a computer 3101 (e.g., computer 3101 in Figure 30A), a controller 3102 (e.g., controller 3002 in Figure 30A), a reflective display 3104 (e.g., reflective display 3004 in Figure 30A), and an irradiator 3106 (e.g., irradiator 3006 in Figure 30A). System 3100 also includes an optical device 3110 which may include an optical diffraction device, for example, the optical diffraction device 1000 in Figures 10A and 10B, 1200 in Figure 12A, 1250 in Figure 12B, or 1270 in Figure 12C, or 1500 in Figure 15. In some implementations, as illustrated in Figure 31A, the optical device 3110 includes a transmission field lattice structure 3112 on a substrate 3111. The transmission field grating structure 3112 can include three corresponding different gratings for three different colors of light.

The controller 3102 is configured to receive graphic data corresponding to one or more objects from the computer 3101 (for example, by using a 3D software application such as Unity), perform calculations on the graphic data, generate control signals for modulation, and transmit them to the display 3104 through the memory buffer 3103. The controller 3102 is also coupled to the irradiator 3106 and is configured to provide a timing signal 3105 to actuate the irradiator 3106 to provide input light 3120. The input light 3120 is then diffracted by the transmission field grating 3112 of the optical device 3110 to illuminate the display 3104. The first portion of the input light 3120 incident on the display elements of the display 3104 is diffracted by the display 3104, and the diffracted primary light 3121 forms a holographic light field 3122 toward the viewer. The holographic light field 3122 can correspond to a reconstructed cone (or frustum of a cone) with a viewing angle. The second portion of the input light 3120 entering the gap of the display 3104 is reflected by the display 3104 and becomes the zero-order display light 3123.

The transmission field grating 3112 is configured to diffract input light 3120 of different colors outward from the irradiator 3106, illuminating the display 3104 off-axis at a certain incident angle greater than half the viewing angle of the reconstruction cone (or frustum of a cone), for example, -6° in air or about -4° in glass. By applying a third technique, the diffracted primary light 3121 exits the display 3104 in the same manner as if the input light 3120 were incident perpendicularly on the axis, while the display zero-order light 3123 exits at a reflection angle identical to the incident angle outside the reconstruction cone.

As illustrated in Figure 31A, system 3100 may include an optical redirection structure having three corresponding zero-order redirection gratings 3114, 3116, and 3018 for different colors of light (blue, green, and red). Each zero-order redirection grating 3114, 3116, and 3118 may be similar to the redirection grating 2416 in Figure 24. Each zero-order redirection grating 3114, 3116, and 3118 may be a holographic grating, such as a Bragg grating, for the corresponding color of light.

The zero-order redirection grids 3114, 3116, and 3118 can be sequentially arranged on the substrate 3111 opposite the transmission field grid structure 3112. In some implementations, as illustrated in Figure 31A, each zero-order redirection grid 3114, 3116, and 3118 for different colored light (blue, green, and red) is recorded on a corresponding recording material, e.g., a photosensitive polymer, and protected by corresponding cover glasses 3113, 3115, and 3117. As described above, the zero-order redirection grids 3114, 3116, and 3118 for three different colored light can be recorded on the same recording material, e.g., a photosensitive polymer, and protected by cover glasses. The three zero-order redirection grids 3114, 3116, and 3118 can have substantially different fringe plane inclinations, which can reduce color crosstalk.

As illustrated in Figure 31A, the blue zero-order redirection grating 3114 is configured to diffract the blue zero-order light of the display from approximately -6° in air (approximately -4° in glass) to approximately +45° (approximately +28° in glass), for example, to redirected blue zero-order light of the display 3124. The green zero-order redirection grating 3116 is configured to diffract the green zero-order light of the display from approximately -6° in air (approximately -4° in glass) to approximately -45° (approximately -28° in glass), for example, to redirected green zero-order light of the display 3126. The red zero-order redirection grating 3118 is configured to diffract the red zero-order light of the display from approximately -6° in air (approximately -4° in glass) to a Blue Star angle of approximately -57° (approximately -37° in glass), for example, to redirected red zero-order light of the display 3128. If the red zero-order light of the display has a p-polarized state, the red zero-order light of the display can be completely transmitted into the air. The optical device 3110 may include one or more light absorbers (e.g., light absorber 2619 in Figure 26A) on one or more edges of the optical device 3110 to reduce Fresnel reflection of blue and green zero-order light of the display at the interface between the cover glass and the air.

If all three color zero-order display light sources have a p-polarized state, for example, when the input light is p-polarized, the optical redirection device may include a zero-order redirection grating for the three different color zero-order display light sources, configured to diffract all three different color zero-order display light sources into the air at the Blue Star angle, which can reduce Fresnel reflection. One or more diffraction gratings can be used together to redirect light of a specific color.

As illustrated in Figure 31B, the optical device 3160 of system 3150 includes a blue redirection grid 3164, a pair of green redirection grids 3166-1 and 3166-2, and a red redirection grid 3168, which are recorded on corresponding recording media and protected by corresponding cover glasses 3163, 3165-1 and 3165-2, and 3167. The blue zero-order redirection grid 3164 is configured to diffract blue zero-order display light from approximately +6° in air (approximately +4° in glass) to a Blue Star angle of approximately -57° in air (approximately -37° in glass), for example, redirected red zero-order display light 3154. The green zero-order display light is first diffracted by a first green zero-order redirection grating 3166-1 from approximately +6° in air (approximately +4° in glass) to approximately +70° (approximately +38° in glass), and then diffracted by a second green zero-order redirection grating 3166-2 to a Blue Star angle of approximately -57° in air (approximately -37° in glass), for example, to redirected green zero-order display light 3156. The red zero-order redirection grating 3168 is configured to diffract the red zero-order display light from approximately +6° in air (approximately +4° in glass) to a Blue Star angle of approximately +57° (approximately +37° in glass), for example, to redirected red zero-order display light 3158. The four zero-order redirection grids 3164, 3166-1, 3166-2, and 3168 can have substantially different fringe plane inclinations, which can reduce color crosstalk.

To reduce color crosstalk between zero-order display light of different colors, the optical redirection device can be configured to redirect zero-order display light of different colors in different directions within the sample plane, as illustrated in Figures 30A–30B and 31A–31B. The optical redirection device can also be configured to redirect zero-order display light of different colors toward different planes in space, as illustrated in Figure 32.

Figure 32 illustrates an exemplary system 3200 that includes an optical device 3210 that redirects zero-order display light of three different colors (e.g., blue, green, and red) in different directions away from the corresponding holographic scene in space.

Similar to the optical device 3110 in Figure 31A, the optical device 3210 includes a transmission field lattice structure 3212, which is the same as the transmission field lattice structure 3112 in Figure 31A, and is configured to diffract each color input light to illuminate the display 3104 off-axis at a certain incident angle, for example, -6° in air or about -4° in glass, which is greater than half the viewing angle of the reconstructed cone (or frustum of a cone). By applying a third technique, the diffracted primary light exits the display 3104 in the same manner as when the input light is incident perpendicularly and on the axis. As described above, light with a larger wavelength corresponds to a larger viewing angle. As illustrated in Figure 32, the diffracted blue primary light forms a blue holographic light field 3220, the diffracted green primary light forms a green holographic light field 3222, and the diffracted red primary light forms a red holographic light field 3224.

Similar to the optical device 3110 in Figure 31A, the optical device 3210 includes a blue redirection grid 3214, a green redirection grid 3216, and a red redirection grid 3218, which are recorded on different recording media and sequentially arranged on the opposite side of the substrate 3211 relative to the transmission field grid structure 3212. The blue redirection grid 3214, green redirection grid 3216, and red redirection grid 3218 are protected by corresponding blue, green, and red cover glasses 3213, 3215, and 3217, respectively. However, unlike the redirection grids 3114, 3116, and 3118 in Figure 31A, the redirection grids 3214, 3216, and 3218 redirect the zero-order display light of the corresponding color to different planes.

For example, as illustrated in Figure 32, the blue redirection grating 3214 diffracts the blue display zero-order light from approximately -6° in air (approximately -4° in glass) to an upward Blue Star angle of approximately +57° in air (approximately +37° in glass), for example, upward redirected blue zero-order light 3230. The red redirection grating 3218 redirects the red display zero-order light from approximately -6° in air (approximately -4° in glass) to a downward Blue Star angle of approximately -57° in air (approximately -37° in glass), for example, downward redirected red zero-order light 3234. The green redirection grid 3216 redirects the green display zero-order light from approximately -6° in air (approximately -4° in glass) to a rightward Blue Star angle (approximately +57° in air, approximately +37° in glass), for example, to a rightward redirected green zero-order light 3232 perpendicular to the plane of the upward redirected blue zero-order light 3230 and the downward redirected red zero-order light 3234. Note that the blue 3214 and red redirection grids 3218 have different fringe plane inclination and/or orientation than the green redirection grid 3216, which can suppress color crosstalk.

Figure 33 illustrates another exemplary system 3300 that redirects three different colored display zero-order lights from a holographic scene in different directions using at least one switchable grating for at least one corresponding color display zero-order light.

Similar to the optical device 3110 in Figure 31A, the optical device 3310 in system 3300 includes a blue redirection grid 3314, a green redirection grid 3316, and a red redirection grid 3318, sequentially arranged on the opposite side of the substrate 3111 from the transmission field grid structure 3112. The blue, green, and red redirection grids 3314, 3316, and 3318 are protected by corresponding blue, green, and red cover glasses 3313, 3315, and 3317. Similar to the blue 3114 and red redirection grid 3118 in Figure 31A, the blue 3314 and red redirection grid 3318 are permanently recorded on the corresponding recording medium.

However, unlike the green redirection grid 3116 in Figure 31A, which is permanently recorded on a corresponding recording medium, the green redirection grid 3316 is recorded on a switchable recording material, such as an electrically switchable holographic polymer-dispersed liquid crystal (HPDLC) material, and is configured to be switchable between different states. For example, the green redirection grid 3316 can be switched to a first state during a first interval of a field continuous color (FSC) irradiation sequence when only green light is present. During the first green-only interval, the switchable green redirection grid 3316 in the first state diffracts the green display zero-order light to a downward angle from approximately -6° in air (approximately -4° in glass) to approximately -45° in air (approximately -28° in glass), for example, redirected green display zero-order light 3338.

During other intervals of the FSC color irradiation sequence, if only red or blue light is present, the switchable green redirection grating 3316 is switched to a second state in which the switchable green redirection grating does not diffract red or blue light. As illustrated in Figure 32, the blue redirection grating 3314 diffracts the blue display zero-order light from an upward angle of approximately -6° in air (approximately -4° in glass) to approximately +45° in air (approximately +28° in glass), for example, upward redirected blue zero-order light 3336. The red redirection grating 3318 redirects the red display zero-order light from an upward angle of approximately -6° in air (approximately -4° in glass) to approximately -45° in air (approximately -28° in glass), for example, downward redirected red zero-order light 3340. The redirected red zero-order light 3340 has the same direction as the redirected green zero-order light 3338, but the switchable green redirection grating 3316 can be switched between a first state, which is all, some, or part of a first interval for redirecting green light, and a second state, which is all, some, or part of the other interval for transmitting red or blue light, thereby suppressing color crosstalk.

In some implementations, two or more separate switchable gratings can be used for two or more corresponding colors with few or no permanently recorded gratings, which can further suppress color crosstalk. In some implementations, a binary (on/off) switchable grating can be replaced with a switchable grating where a first switching state diffracts a first color and a second switching state diffracts a second color, which can allow for less or no permanently recorded grating use.

Figure 34 is a flowchart of an exemplary process 3400 for suppressing zero-order display light in a holographic scene. Process 3400 can be implemented in a system for reconstructing 2D or 3D objects. The system can be any preferred system, for example, system 500 in Figure 5A, 520 in Figure 5B, 530 in Figure 5C, 540 in Figure 5D, 560 in Figure 5E, 570 in Figure 5F, 580 in Figure 5G, 590 in Figure 5H, 590A in Figure 5I, 590B in Figure 5J, 590C in Figure 5K, 1800 in Figure 18, 1950 in Figure 19B, 1980 in Figure 19C, 2100 in Figure 21, 2200 in Figure 22, 2300 in Figure 23A, and 23B. This could be 2350 in Figure 24, 2400 in Figure 24, 2600 in Figure 26A, 2630 in Figure 26B, 2650 in Figure 26C, 2670 in Figure 26D, 2690 in Figure 26E, 2700 in Figure 27A, 2730 in Figure 27B, 2750 in Figure 27C, 2800 in Figure 28, 2900 in Figure 29, 3000 in Figure 30A, 3030 in Figure 30B, 3100 in Figure 31A, 3150 in Figure 31B, 3200 in Figure 32, or 3300 in Figure 33.

In 3402, the display is illuminated with light. A first portion of the light illuminates the display elements of the display. In some cases, a second portion of the light illuminates the gap between adjacent display elements. The display may be the display 1610 in Figure 16, the display elements may be the display elements 1612 in Figure 16, and the gap may be the gap 1614 in Figure 16.

In 3404, the display elements of the display are modulated with a hologram corresponding to holographic data, diffracting a first portion of light to form a holographic scene corresponding to the holographic data, and suppressing display zero-order light in the holographic scene. Display zero-order light may include a second portion of reflected light from the display, for example, light reflected in the gap. Reflected light from the display may be the primary order of display zero-order light. Display zero-order light may also include any unwanted or undesirable light, for example, diffracted light in the gap, reflected light on the surface of the display elements, and reflected light on the surface of the display cover that covers the display. The holographic scene corresponds to a reconstructed cone (or frustum of a cone) with a viewing angle. The hologram is configured such that display zero-order light is suppressed in the holographic scene. The hologram may be configured such that the diffracted first portion of light has at least one characteristic different from that of display zero-order light. At least one characteristic may include power density (e.g., as illustrated in Figure 18), beam divergence (e.g., as illustrated in Figure 18), propagation direction away from the display (e.g., as illustrated in Figures 19B, 19C, 20B, and 21-33), or polarization state.

Display zero-order light is suppressed in the holographic scene by light suppression efficiency. Light suppression efficiency can be defined as the result of subtracting from 1 the ratio of the amount of display zero-order light in the holographic scene with suppression to the amount of display zero-order light in the holographic scene without any suppression. In some examples, the light suppression efficiency exceeds a predetermined percentage, such as 50%, 60%, 70%, 80%, 90%, or 99%. In some examples, the light suppression efficiency is 100%.

In some implementations, process 3400 further includes determining the EM field contribution to each of the display elements of the display by calculating the electromagnetic (EM) field propagation from the primitive to the display element in a global three-dimensional (3D) coordinate system for each of the multiple primitives corresponding to the object, and generating the sum of the EM field contributions from the multiple primitives to the display element for each of the display elements. The holographic data may include the sum of the EM field contributions from the multiple primitives of the object to the display elements of the display. If the display is phase-modulated, the holographic data may include the phase for each of the display elements of the display. The holographic scene may include the reconstructed object corresponding to the object. The holographic data may include information for two or more objects.

In some implementations, as discussed above with respect to the first technique, "phase calibration," the hologram can be constructed by adjusting the phase of each display element to have a predetermined phase range, for example, [0, 2π]. In some implementations, each phase is given by the following equation (15)
It can be adjusted according to
During the ceremony,
These represent the initial phase values of each phase,
A and B represent the adjusted phase values for each phase, and A and B are constants for each phase. Constants A and B can be adjusted so that the light suppression efficiency of the holographic scene is maximized or exceeds a predetermined threshold, for example, 50%, 60%, 70%, 80%, 90%, or 99%. In some implementations, constants A and B are adjusted by a machine vision algorithm or a machine learning algorithm.

In some implementations, as discussed above with respect to the second technique, "zero-order beam divergence," the optical divergence component is located downstream of the display. The optical divergence component may be a defocusing element including a concave lens, for example, the concave lens 1802 in Figure 18. The optical divergence component may be a focusing element including a convex lens. The diffracted first portion of light is guided through the optical divergence component to form a holographic scene, while the display zero-order light diverges within the holographic scene. The light illuminating the display can be collimated, and the display zero-order light can be collimated before reaching the optical divergence component, and the hologram is configured such that the diffracted first portion of light converges before reaching the optical divergence component. The optical divergence component may be a focusing element including a cylindrical lens. The optical divergence component may be a lenslet array including concave, convex, or cylindrical lenses, or a combination thereof. An optical divergent element may be one or more holographic optical elements (HOEs) that are either added to an optical device or incorporated within one or more other diffraction layers of the optical device. One or more HOEs may be configured to add a more complex transfer function to the optical divergent element, such as by focusing, diverging, or linearly focusing light, or directing the display zero-order light to a region outside the reconstruction cone of the holographic scene. The region may include an annular or peripheral region, or a portion of an annular or peripheral region. The light illuminating the display may be collimated, and the hologram may be configured so that the diffracted first portion of light is shaped by a shaping effect before reaching the optical divergent element, such that the effect of the optical divergent element on the first portion of the light compensates for the shaping effect.

In some examples, the hologram is constructed by adding a virtual lens, for example, by adding a corresponding phase to each phase for each display element, and the corresponding phase for each display element is compensated for by an optical divergence component such that the holographic scene corresponds to each phase for each display element. The corresponding phase for each display element is given by the following equation (16)
It can be represented by,
During the ceremony,
λ represents the corresponding phase for the display element, λ represents the wavelength of light, f represents the focal length of the optical divergent component, x and y represent the coordinates of the display element in the coordinate system, and a and b represent constants.

In some examples, a hologram is constructed in a 3D software application, such as Unity, by moving a configuration cone relative to the display in a direction perpendicular to the display, with respect to the global 3D coordinate system, by a distance corresponding to the focal length of the optically divergent components. The configuration cone corresponds to the reconstruction cone and has the same apex angle as the field of view. The software application can generate primitives of objects based on the moved configuration cone in the global 3D coordinate system.

Process 3400 may include displaying a holographic scene on a two-dimensional (2D) screen, for example, on a projection screen 1830 in Figure 18, spaced apart from the display along a direction perpendicular to the display. The 2D screen can be moved along the direction to obtain different slices of the holographic scene on the 2D screen.

Process 3400 may further include inducing light to illuminate the display. In some examples, light is induced by a beam splitter, for example, beam splitter 1810 in Figure 18, to illuminate the display, and the diffracted first portion of the light and the zero-order light of the display are transmitted through the beam splitter.

In some implementations, the display is illuminated with light at a perpendicular incidence, as illustrated, for example, in Figure 18 or 19A. In some implementations, the display is illuminated with light at an incidence angle that can be greater than half of the viewing angle, as illustrated, in Figure 19B or 19C.

In some implementations, as discussed above with respect to the third technology, "zero-order optical deviation," the hologram is configured such that the first diffracted portion of light forms the same reconstructed cone as the first diffracted portion of light when light is incident perpendicularly to the display, while the second reflected portion of light exits the display at the same angle of reflection as the angle of incidence, as illustrated in Figure 19B or 19C.

In some examples, the hologram is constructed by adding a virtual prism, for example, by adding a corresponding phase to each phase for each display element, and the corresponding phase for each display element is compensated by the angle of incidence so that the holographic scene corresponds to each phase for each display element. The corresponding phase for each display element is given by the following equation (17)
It can be represented by,
During the ceremony,
λ represents the corresponding phase for the display element, λ represents the wavelength of light, x and y represent the coordinates of the display element in the global 3D coordinate system, and θ represents the angle corresponding to the angle of incidence.

In some examples, holograms are constructed by moving a constituent cone relative to the display with respect to a global 3D coordinate system, or, as illustrated in Figure 20B, by rotating the constituent cone relative to the surface of the display with respect to a global 3D coordinate system by a certain rotation angle, where the rotation angle corresponds to the angle of incidence.

In some implementations, as discussed above regarding the fourth technique, "zero-order light blocking," the zero-order light of the display is blocked so that it appears in the holographic scene. The light suppression efficiency of the holographic scene can be 100%.

In some examples, the optical barrier component is located downstream of the display. The optical barrier component may include multiple microstructures or nanostructures. It may include a metamaterial layer, e.g., the metamaterial layer 2316 in Figures 23A-23B, or a louver film, e.g., the anisotropic transmitter in Figure 28. The optical barrier component is configured to transmit a first light beam having an angle smaller than a predetermined angle and to block a second light beam having an angle larger than a predetermined angle, where the predetermined angle is smaller than the incident angle and greater than half the viewing angle. Therefore, as illustrated in Figures 23A and 23B, the zero-order light of the display is blocked by the optical barrier component, and the diffracted first portion of the light is transmitted through the optical barrier component with a certain transmission efficiency, forming a holographic scene. The transmission efficiency is a predetermined ratio, e.g., 50%, 60%, 70%, 80%, 90%, or 99% or higher.

In some implementations, process 3400 further includes guiding light to illuminate a display by guiding the light through an optical diffraction element on the substrate, which is configured to diffract light at an angle of incidence. The optical diffraction element may be the out-coupler 1914 in Figure 19A, 1964 in Figures 19B or 19C, or the transmission field grating structure 2414 in Figure 24. In some examples, the light is guided to the optical diffraction element through a waveguide coupler, e.g., the in-coupler 1916 in Figure 19A, or 1966 in Figures 19B or 19C. In some examples, the light is guided to the optical diffraction element through a coupled prism, e.g., the coupled prism 2111 in Figure 21, or 2311 in Figures 23A or 23B. In some examples, the light is guided to the optical diffraction element through a wedge-shaped surface of the substrate, as illustrated, for example, in Figure 22.

As illustrated in Figure 23A or 23B, the optical diffraction component is formed on the first surface of the substrate facing the display, and the optical shielding component is formed on the second surface of the substrate opposite to the first surface.

In some implementations, as discussed above with respect to the fifth technique, "zero-order optical redirection," the optical redirection component is positioned downstream of the display and is configured to transmit the diffracted first portion of light to form a holographic scene, and to redirect the display zero-order light from the holographic scene. The optical redirection components may be the zero-order redirection lattice structure 2416 in Figure 24, 2616 in Figure 26A, 2646 in Figure 26B, 2666 in Figure 26C or 26D, 2694 in Figure 26E, 2716 in Figure 27A, 2746 in Figure 27B or 27C, 2816 in Figure 28, 2916 in Figure 29, 3016 and 3018 in Figure 30A, 3046 and 3048 in Figure 30B, 3114, 3116, and 3118 in Figure 31A, 3164, 3166-1, 3166-2, and 3168 in Figure 31B, or 3214, 3216, and 3218 in Figure 32, or 3314, 3316, and 3318 in Figure 33.

The optical redirection component can be configured to diffract a first light beam having the same angle as a predetermined angle with substantially greater diffraction efficiency than a second light beam having a different angle, where the predetermined angle is substantially the same as the incident angle. The optical redirection component may include one or more holographic gratings, such as Bragg gratings.

In some implementations, the optical diffraction component is formed on a first surface of the substrate facing the display, and the optical redirection component is formed on a second surface of the substrate opposite the first surface, as illustrated, for example, in Figures 24-33.

The optical redirection component is configured such that the zeroth-order light of the display is diffracted outwards in three-dimensional (3D) space along at least one of the following directions: upward, downward, leftward, rightward, or a combination thereof. The light suppression efficiency of the holographic scene can be 100%. In some examples, as illustrated in Figure 26A, the angle of incidence of the light is negative, e.g., -6° in air, and the diffraction angle of the zeroth-order light of the display diffracted by the optical redirection component is negative, e.g., -45° in air. In some examples, as illustrated in Figure 26B, the angle of incidence of the light is positive, e.g., +6° in air, and the diffraction angle of the zeroth-order light of the display diffracted by the optical redirection component is positive, e.g., +45° in air. In some examples, as illustrated in Figure 26C or 26D, the angle of incidence of the light is negative, e.g., -6° in air, and the diffraction angle of the zeroth-order light of the display diffracted by the optical redirection component is positive, e.g., +45° in air. In some examples, the angle of incidence of light is positive, +6°, in air, while the diffraction angle of the zero-order light of the display diffracted by the optical redirection component is negative, for example, -45°, in air.

The optical redirection component can be covered by a second substrate, for example, the cover glass 2618 in Figure 26A. The optical redirection component can be configured to redirect the zero-order light of the display to a light absorber, for example, the light absorber 2619 in Figure 26A or 2649 in Figure 26B, which is formed on the side of the second substrate or at least one of the sides of the substrate. The second substrate may include an anti-reflective (AR) coating, for example, the AR coating 2682 in Figure 26D on the surface of the second substrate opposite the optical redirection component. The anti-reflective coating is configured to transmit the zero-order light of the display and prevent Fresnel reflection of the zero-order light of the display. The anti-reflective coating may also be configured to reduce or eliminate reflection of ambient light from the viewer and reflection of the environment reflected from the viewer-facing front surface of the second substrate, for example, the AR coating 2682 in Figure 26D. The final AR coating can be designed not to interfere with the five techniques described herein, which depend on the characteristics of the final transition to air on the viewer side. Preventing Fresnel reflection from the front prevents the viewer from seeing the room light reflected by the front. Deeper surfaces within the optical device exhibit only relatively small changes in refractive index, thus resulting in minimal Fresnel reflection from the observer and room light reflecting back towards the viewer. Alternatively, the surface can be AR coated, or, as in the case of a rear reflector for a display, the surface may be behind multiple absorbing layers, such as linear polarizers, where ambient illumination creates a double pass and is therefore attenuated. The effect can be enhanced by adding or incorporating layers of material with a cumulative optical density in the range of 0.2 to 1.0 into the device.

In some implementations, the zero-order display light is p-polarized before reaching the second substrate. As illustrated in Figure 27A, the optical redirection component can be configured to diffract the zero-order display light so that it is incident at a Brewster angle at the interface between the second substrate and the surrounding medium, such as air, so that the zero-order display light is completely transmitted through the second substrate.

In some implementations, the zero-order light of the display is s-polarized before reaching the second substrate. Process 3400 may further include converting the polarization state of the zero-order light of the display from s-polarization to p-polarization. In some examples, the conversion of the polarization state of the zero-order light of the display is performed by an optical retarder (e.g., optical retarder 2747 in Figure 27B) (and optionally, a linear polarizer) positioned upstream of the optical redirection component relative to the display. In some examples, the conversion of the polarization state of the zero-order light of the display is performed by an optical retarder (e.g., optical retarder 2747 in Figure 27C) (and optionally, a linear polarizer) positioned downstream of the optical redirection component relative to the display. The optical retarder can be formed on the side of the second substrate opposite to the optical redirection component, and the optical retarder can be covered by a third substrate (e.g., retarder cover glass 2762 in Figure 27C).

In some implementations, as illustrated in Figure 28, the optical blocking component is formed on the side of the second substrate facing the optical redirection component. The optical blocking component is configured to transmit a first diffracted portion of light and absorb the zero-order display light diffracted by the optical redirection component. In some examples, the optical blocking component includes an anisotropic transmitter (e.g., anisotropic transmitter 2820 in Figure 28) configured to transmit a first light beam having an angle smaller than a predetermined angle and absorb a second light beam having an angle larger than a predetermined angle. The predetermined angle is greater than half the viewing angle and smaller than the diffraction angle at which the zero-order display light is diffracted by the optical redirection component.

In some implementations, as illustrated in Figure 29, the optical redirection component is configured to diffract the zero-order display light and direct it to the interface between the second substrate and the surrounding medium at an angle greater than the critical angle. Therefore, the zero-order display light diffracted by the optical diffraction component is completely reflected at the interface. A light absorber, for example, the light absorber 2920 in Figure 29, can be formed on the substrate and the side surfaces of the second substrate and configured to absorb the completely reflected zero-order display light.

In some implementations, as illustrated in Figures 30A to 33, the light comprises multiple different colors, and the optical diffraction component is configured to diffract the multiple different colors of light at the angle of incidence on the display. The optical redirection component includes separate optical redirection subcomponents for each of the multiple different colors of light.

In some implementations, as illustrated in Figure 30B, each optical redirection subcomponent for multiple different colored lights is recorded in the same recording structure, or in adjacent recording structures separated only by a thin optical index layer, contact layer, or adhesive layer. In some implementations, as illustrated in Figures 30A, 31A, 31B, 32, and 33, each optical redirection subcomponent for multiple different colored lights is recorded in different corresponding recording structures that may be separated by a cover glass.

An optical redirection component can be configured to diffract multiple different colored lights in different directions and at different diffraction angles in 3D space. In some examples, as illustrated in Figures 31A-31B, the optical redirection component is configured to diffract at least one of the multiple different colored lights and incident it at the interface at at least one Brewster angle. The interface can include one of the interfaces between the upper substrate and the surrounding medium, or between two adjacent substrates.

In some implementations, as illustrated in Figure 32, the optical redirection component is configured to diffract light of a first color (e.g., blue) and a second color (e.g., red) in a plane, as well as light of a third color (e.g., green) perpendicular to the plane.

In some implementations, as illustrated in Figure 31B, the optical redirection component includes at least two different optical redirection subcomponents (e.g., redirection gratings 3166-1, 3166-2 in Figure 31B) configured to diffract light of the same color from among multiple different colors of light. The two different optical redirection subcomponents can be arranged sequentially within the optical redirection component.

Inducing light to illuminate a display can include sequentially inducing multiple different colored lights to illuminate the display over a series of periods. In some implementations, as illustrated in Figure 33, the optical redirection component may include a switchable optical redirection subcomponent (e.g., the switchable green redirection grid 3316 in Figure 33) configured to diffract light of a first color in a first state during all, part, or part of a first period, and transmit light of a second color in a second state during all, part, or part of a second period.

In some implementations, a switchable optical redirection subcomponent is configured to diffract light of a first color in a first state during all, part, or portion of a first period, and to diffract light of a second color in a second state during all, part, or portion of a second period.

Multiple different colored lights may include a first color of light and a second color of light, where the first color of light has a shorter wavelength than the second color of light. In the optical redirection component, the first optical redirection subcomponent for the first color of light can be positioned closer to the display than the second optical redirection subcomponent for the second color of light, as illustrated in Figures 30A-33.

In some implementations, the fringe planes of at least two optical redirection subcomponents for at least two different colors of light are oriented in substantially different directions.

In some implementations, the optical redirection component includes a first optical redirection component configured to diffract light of a first color, a second optical redirection component configured to diffract light of a second color, and at least one optical retarder (and optionally, a linear polarizer) positioned between the first and second optical redirection subcomponents and configured to transform the polarization state of the light of the first color so that the light of the first color is transmitted through the second optical redirection component.

The second, reflected portion of the light has the same angle of reflection as the angle of incidence and propagates outside the holographic scene. In some examples, half of the field of view is within the range of -10 to 10 degrees, or -5 to 5 degrees. In some examples, the angle of incidence is -6 degrees or 6 degrees.

In some implementations, the optical redirection component is configured to allow the display zero-order light to pass through unchanged, redirecting the diffracted first portion of the light to form a holographic scene corresponding to a cone or frustum of a predetermined angle, away from the display zero-order light.

In some implementations, the optical redirection component is configured to redirect the zero-order display light toward a first direction and redirect the diffracted first portion of the light toward a second direction away from the first direction. For example, the diffracted first portion of the light can be redirected perpendicular to the wedge-shaped surface of the substrate, and the zero-order display light can be redirected to strike the wedge-shaped surface beyond a critical angle, and thus return into the substrate and undergo total internal reflection (TIR).

Additional aspects of displaying the reconstructed three-dimensional object Implementations of this disclosure include holographic light fields, for example, holographic light fields 518 in Figure 5A, 528 in Figure 5B, 538 in Figure 5C, 548 in Figure 5D, 568 in Figure 5E, 578 in Figure 5F, 599-1 or 599-2 in Figures 5H, 5I, 5J, or 5K, 2422 in Figure 24, 2622 in Figure 26A, 2632 in Figure 26B, 26C, 26D, or 26 In Figures E 2652, Figure 27A 2702, Figure 27B or 27C 2732, Figure 28 2802, Figure 29 2902, Figure 30A or 30B 3022, Figure 31A or 31B or 33 3122, or Figures 3220, 3222, and 3224, a display system for displaying reconstructed three-dimensional (3D) objects is provided. The techniques described herein can improve the performance of the display system by improving one or more properties of the holographic light field (e.g., size or zero-order suppression) by, for example, using a larger reflective display, using a larger grating, and/or controlling the input light. For illustrative purposes only, the techniques are considered with reference to system 3100 in Figure 31A.

First exemplary method – Using a larger reflective display One way to increase the size of the holographic light field 3122 in Figure 31A is to construct the same optical geometry using a larger reflective display 3104 and a proportionally larger substrate 3111 with a constant beam angle.

As the linear range of the reflective display 3104 increases, the front area of the substrate 3111 increases as squared by the increase in the linear range of the reflective display 3104. If the beam angle and beam distribution remain unchanged, the thickness of the substrate 3111 increases with the increase in the linear range of the reflective display 3104. As a result, the volume of the substrate 3111 can increase as cubed by the increase in the linear range of the reflective display 3104. For example, doubling the width of the reflective display 3104 while maintaining the same width-height aspect ratio and proportional thickness of the substrate 3111 quadruples the front area of the substrate 3111 and increases the volume of the substrate 3111 eightfold. Ultimately, the increased thickness and high cost of the substrate 3111 may be undesirable, for example, because it may be desirable to maintain optical-grade clarity, where the substrate 3111 is substantially free of significant inclusions, absorptions, scatterings, birefringences, and/or other visible optical defects or imperfections.

The weight of the substrate 3111 may also be undesirable. For example, the substrate 3111 may have a thickness of about 20% of the height of the reflective display 3104. As an example, for a 686 mm (27 inch) diagonal reflective display 3104 with a 16:9 aspect ratio (typical dimensions for computer monitors), the substrate 3111 may have dimensions of 598 mm × 336 mm × 68 mm or larger. If such a substrate 3111 is made from a solid block ^of acrylic with a density of 1.17 to 1.20 g/cm³, the weight of the substrate 3111 may be at least 16 kg (35 lbs). For a similar 1,650 mm (65 inch) diagonal reflective display 3104 with a 16:9 aspect ratio, the substrate 3111 may be at least 165 mm thick and weigh at least 225 kg (495 lbs), which may be difficult to ship, install, and move. Mounting and support structures for such acrylic blocks can also be large and heavy.

Furthermore, if all or part of the holographic light field 3122 is projected into the visual space in front of the final cover glass 3113, it may be desirable for the holographic light field 3122 to be positioned proportionally further forward of the front cover glass 3113 (for example, beyond 165 mm in front of the reflective display 3104 having a diagonal of 1,650 mm). This may reduce the field of view and resolution. If a smaller, zero, or negative Z-axis translation is applied, the holographic light field 3122 may appear deeper behind the front of the front cover glass 3113.

To address the above issues, the substrate 3111 can be made thinner, which may reduce its mass and cost, and impose fewer constraints on the substrate's z-position and field of view.

In some embodiments, the substrate 3111 can be made of a material with a lower density and/or refractive index that allows for more extreme angles and beam angle changes of the beam entering and exiting the substrate 3111. For example, the liquid-filled substrate 3111 can be used with a liquid having a refractive index that may be lower than that of acrylic (e.g., 17% to 20% lower), such as water or oil. The liquid can be sealed in a tank, which can help solve certain potential transportation and installation problems, as the tank can be transported empty and then filled in place.

In certain embodiments, the angle of the input light 3120 refracted within the substrate 3111 can be increased with respect to one or more wavelengths of the input light 3120. This may allow the use of a relatively thin substrate 3111 for the input light 3120 to illuminate the same area of a reflective display 3104, for example. In some cases, it may be desirable to select an angle to achieve a specific diffraction efficiency and/or to satisfy desired critical angle characteristics.

In some embodiments, the substrate 3111 can be wedge-shaped, similar to the substrate 1252 in Figure 12B or the substrate 1272 in Figure 12C, so that the incident angle of the input light 3120 on the field grid 3112 can be relatively large.

In certain embodiments, two or more irradiators can be used to illuminate different areas of the reflective display 3104 from, for example, from above and below, respectively. For example, a first irradiator 3106 that provides a first input light 3120 to a first end face of the substrate 3111 (e.g., the lower end face of the substrate 3111) can be used to illuminate only a first area (e.g., the lower half) of the reflective display 3104. A second irradiator (which can be similar to the first irradiator 3106) that provides a second input light (which can be similar to the first input light 3120) to a second end face of the substrate 3111 (e.g., the upper end face of the substrate 3111) can be used to illuminate only a second area (e.g., the upper half) of the reflective display 3104. Such an arrangement can allow the reflective display 3104 to be fully illuminated while enabling the substrate 3111 to be relatively thin (e.g., the thickness of the substrate 3111 to be halved). Optionally, a third, fourth, or more input light beams, each input through different corresponding end faces of the substrate 3111 (e.g., the left and right end faces of the substrate 3111), can be used to illuminate areas of the reflective display 3104 (e.g., the left and right regions, respectively).

In some embodiments, the input light can illuminate different areas of the reflective display 3104 along different optical paths. For example, a first irradiator 3106 that provides a first input light 3120 to an end face of the substrate 3111 (e.g., the lower end face of the substrate 3111) and directly illuminates the transmission field grating 3112 can be used in combination with a second irradiator that provides a second input light to an end face of the substrate 3111 (which may be the same end face used by the first input light), but the second input light is first directed forward toward the redirection grating 3114 and then reflected toward the transmission field grating 3112, so that the first input light illuminates a first area (e.g., the upper half) of the reflective display 3104 and the second input light illuminates a second adjacent area (e.g., the lower half) of the reflective display 3104. Such reflection of the second input light can be achieved by using total internal reflection (TIR) or a reflection grating at or before the surface of the redirection grating 3114 (e.g., by the interface between the substrate 3111 and the redirection grating 3114). Alternatively, a partial reflection surface (e.g., a 50:50 or gradient or patterned beam splitter) can be incorporated into the substrate 3111 to split a single input light 3120 within the substrate 3111 into two beams, including a first beam that travels directly to the transmission field grating 3112 with reduced optical power, and a second beam that initially travels away from the transmission field grating 3112 with also reduced optical power and is then directed to return to the transmission field grating 3112 by, for example, TIR, or a reflection grating at or before the surface of the redirection grating 3114.

In certain embodiments, the diffraction efficiency of the transmission field grating 3112 can be patterned such that when the input light 3120 first encounters a subregion of the transmission field grating 3112, only a selected proportion of the input light 3120 is diffracted outward toward the reflective display 3104, while all or part of the remaining input light 3120 is reflected into the substrate 3111. The reflected input light 3120 within the substrate 3111 is further reflected by TIR, for example, backward toward a second subregion of the transmission field grating 3112, toward the front surface of the substrate 3111, and the second subregion of the transmission field grating 3112 combines a second portion toward the reflective display 3104 with a diffraction efficiency adjusted so that two such regions of the transmission field grating 3112 illuminate two corresponding subregions of the reflective display 3104 with substantially similar optical power. The process described above can be extended to three or more such sub-regions of the transmission field grid 3112, and therefore to three or more corresponding sub-regions of the reflective display 3104.

In some embodiments, light that was not initially diffracted to the reflective display is reused to illuminate the reflective display. For example, the diffraction efficiency of the transmission field grating 3112 can be patterned or selected such that when the input light 3120 first encounters a first sub-region of the transmission field grating 3112, only a selected proportion of such input light 3120 is diffracted outward toward the reflective display 3104, and all or part of the remaining input light 3120 is reflected toward the substrate 3111. The reflected input light 3120 can eventually travel (for example, by TIR within the substrate 3111, or via a direct path) toward a reflective element attached to or following the end face of the substrate 3111 (for example, a mirror or reflective grating instead of the absorber 1203 in Figure 12B), which reflects it backward through the substrate 3111 (directly or after further TIR or diffraction redirection) to re-irradiate a first or second sub-region of the transmission field grating 3112, causing the sub-region of the transmission field grating 3112 to diffract it outward toward the reflective display 3104.

In some embodiments, each subregion of the reflective display 3104 is made from an individual display device (e.g., LCoS) or any other reflective display device, and the reflective display 3104 is formed by a tiled array of smaller display devices. This makes it possible to compensate for the diffraction efficiency, and therefore the differences in device illumination, for each subregion of the transmission field grating 3112 by operating such smaller display devices having different reflectivity.

In certain embodiments, a relatively high aspect ratio of width to height of the reflective display is used to increase the size of the holographic light field. The thickness of the substrate 3111 generally depends on the irradiated height of the reflective display 3104, but not on the irradiated width of the reflective display 3104. Therefore, as the aspect ratio of the reflective display 3104 increases, the thickness of the substrate 3111 does not need to increase in such a way that its width does not necessarily increase with a corresponding increase in its height. For example, an aspect ratio of 20:9 can be used instead of a 16:9 aspect ratio of width:height. Increasing the aspect ratio of the reflective display 3104 in this way can increase the size of the holographic light field, as the viewer typically has two eyes, primarily in a horizontal arrangement, resulting in stereoscopic vision.

In some cases, when multiple viewers observe a holographic light field display simultaneously, the viewers are likely to be positioned side-by-side (rather than one looking over the other's head), so the wider field of view provided by a higher aspect ratio can be suitable for group viewing. Furthermore, since it has been empirically observed that most viewers of holographic light fields, such as casual viewers, are more likely to move their heads from side to side than up and down, implementing a higher aspect ratio with a wider width can again improve system performance.

In some cases, a useful and comfortable holographic light field display can have a very high aspect ratio (strip or slit display). For example, if the grids 3112, 3114, 3116, and 3118 are tiled horizontally, a wider aspect ratio can be achieved with a relatively thin substrate 3111.

In general, regardless of the aspect ratio of the reflective display 3104 (and therefore the substrate 3111 and the grids 3112, 3114, 3116, and 3118), it is desirable that the width of the input light 3120 is sufficient to illuminate the width of the reflective display 3104 (and the widths of the substrate 3111 and the grids 3112, 3114, 3116, and 3118). For low aspect ratios of the reflective display 3104, the input light 3120 may have a gently elongated rectangular profile or cross-section (or even a square profile or cross-section), which can be implemented by masking or otherwise cutting off a sufficiently large circular or elliptical beam profile from the irradiator 3106.

Second exemplary method – Using a larger grid: When the reflective display 3104 and substrate 3111 are expanded, the transmission field grid 3112 and the display zero-order redirection grids 3114, 3116, and 3118 can also be expanded to match.

In some embodiments, the transmission field grid 3112 can be divided into two or more regions, each utilizing input light entering the substrate 3111 through different edges of the substrate 3111, as described above.

In certain embodiments, larger grids 3112, 3114, 3116, and 3118 can be generated by expanding the recording material of the corresponding optical elements and their respective production systems.

In some embodiments, larger gratings 3112, 3114, 3116, and 3118 can be generated by tiled optical recording, and each sub-region of the grating can be sequentially recorded using smaller optical elements and full-size recording material in a step-and-repeat process. This allows for the use of smaller optical components, which are often relatively inexpensive. Additionally or alternatively, this can allow for the use of lower recording capabilities (e.g., rather than increasing the recording exposure duration), which can enable the use of relatively inexpensive recording laser sources and/or a relatively wide range of laser technologies, wavelengths, and vendors available to provide such sources. Such tiled gratings can also be used to provide multiple regions for extending the transmitted field grating 3112 using multiple input light sources.

The edges of the tiled sub-regions of the grid can touch each other with a slight gap between them. Optionally, the sub-regions can be seamlessly joined, or they can slightly or substantially overlap. A combination of these approaches is possible. In some cases, the slight gap may be invisible or have low visibility for the viewer. For example, when the holographic light field 3122 occupies an optical distance from the viewer that does not include the optical distance of the grid from the viewer, the gap may be out of focus when the viewer's eye is focused on the holographic light field 3122. In certain cases, the slight overlap may have little or no visibility to the viewer. Substantial overlap between two sub-regions of the grid, e.g., 50% overlap, can be implemented to smooth and/or reduce the visibility of the tiled surface and/or to improve the final uniformity of the overlapping grid.

In some cases, to reduce the visibility of such small gaps or overlaps between the tiled subregions of the grid, the grid subregions can be aligned with the gaps between smaller display devices that form the reflective display 3104 as a tiled array of smaller display devices.

In some cases, an effectively seamless grid with no significant gaps or overlaps can be implemented when recording a sub-region grid by including one or more edge-defining elements, e.g., square, rectangular, or otherwise planar tiled apertures, in the optical system of the recording reference and/or object beam, and by projecting or re-imaging the edges formed so that they are substantially firmly focused within the recording material during the recording of the grid or grid. Sharply defined edges can also be achieved when recording a sub-region grid, for example, by using a reflection or transmission phase mask in the optical system of the recording reference and/or object beam.

In some embodiments, larger grids 3112, 3114, 3116, and 3118 can be manufactured using mechanical means rather than optical means, such as embossing, nanoimprinting, or self-assembled structures. Such mechanically produced grids can also be tiled in one or more dimensions, for example, by using roller embossing in a roll-to-roll system.

Third exemplary method – controlling the input light As described above, as the aspect ratio of the reflective display 3104 increases, a more extended rectangular profile for the input light 3120 may become desirable, and a more elliptical beam profile from the irradiator 3106 may also become desirable. Since many laser diodes produce elliptical beams, in some cases the desired beam profile from the irradiator 3106 can be implemented by rotating the ellipticity of the laser diode light source within the irradiator 3106, for example, by mechanically or optically rotating the laser diode light source within the irradiator 3106.

Since many laser diodes emit substantially polarized light, and certain other components of the optical device 3110 may perform better for specific polarization orientations (e.g., they may require specific polarization orientations), it may be desirable to independently rotate the ellipticity and polarization orientation of the light source in the irradiator 3106, for example, by rotating all polarizations of the input light 3120 using a broadband half-wavelength retarder, or by rotating the polarizations of each color of input light 3120 separately using individual narrowband half-wavelength retarders. Because the profile or cross-section of the input light 3120 can vary very widely in both width and height, low-cost half-wave plates, such as polymer waveplates or liquid crystal waveplates, may be more preferable than high-cost half-wave plates, for example, those made from quartz.

In some embodiments, the uniformity of the input light 3120 can be improved by using an arrangement of optical elements such as apodizing optical elements or profile converters, for example, lenses or holographic optical elements (HOEs), or by integrating rods to perform conversions from Gaussian to top-hat and/or circular to rectangular profiles, or by using polarization recycling elements.

In certain embodiments, an anamorphic optical system can be implemented. The aspect ratio of the reflective display 3104 can be increased to such an extent that the desired degree of anamorphicity of the input light 3120 exceeds a threshold degree that can be appropriately provided by a cost-effective light source in the irradiator 3106 without masking off and thus wasting an unacceptable proportion of the light source power. In such cases, the width of the input light 3120 can be further increased by using an anamorphic optical system, such as an anamorphic lens or cylindrical lens, or a HOE that functions as an anamorphic or cylindrical lens or mirror.

Exemplary System Figures 35A–C illustrate an exemplary system 3500 for displaying a reconstructed 3D object. Figures 36A–C show the same diagram of system 3500 as in Figures 35A–C, but with three colors of light (e.g., red, green, and blue) propagating through system 3500.

A rectangular section (as illustrated in Figure 36A) of a substantially coaxial elliptical beam 3501 (e.g., made from three laser diodes of three different colors such as red, green, and blue) from the irradiator 3501S is reflected by the mirror 3502 and then refracted by the first surface 3503 of the prism element 3504. The beam 3501 has a defined width between the upper and lower beams, as illustrated in Figure 36A. The light beams of different colors refracted within the prism element 3504 can be stacked together along a first direction (e.g., as illustrated in Figure 36A) and spaced apart (or overlapping) along a second direction (e.g., as illustrated in Figure 36B). The second surface 3505 of the prism element 3504 reflects the beam to a third surface 3506 of the prism element 3504, on which one or more transmission expansion gratings 3507 are optically stacked (generally one grating per color). Each expansion grating is illuminated by its corresponding color at a relatively high incident angle, e.g., 68°, within the prism element 3504, and is configured to diffract a portion of the illuminated light outward toward a series of reflectors 3508. Effectively, the grating 3507 expands the original rectangular section of the light beam 3501 from the laser diode by a substantial multiple (e.g., about 6 times) of one dimension (e.g., the width illustrated in Figure 36A). The light beam reflected by the prism element 3504 can be absorbed by the absorption layer 3504A applied to the surface of the prism element 3504, due to the third surface 3506 and/or the expansion grating 3507 and/or the cover layer applied to the expansion grating 3507 (e.g., as illustrated in Figure 36A).

Since the light incident on the grating 3507 is incident at a high angle, the depth of the prism element 3504 (e.g., the length of its surface 3505, of which at least a portion is reflective) can be relatively small. The angle of incidence can exceed critical if the light is incident on the grating 3507 from air at such a large angle (refractive index approximately 1.0), causing all of the incident light to be reflected away from the grating. In system 3500, the light is incident from the prism element 3504, which can be made from glass or acrylic having a high refractive index (e.g., approximately 1.5), and therefore the angle of incidence does not exceed critical.

In some embodiments, the reflector 3508 may include three dichroic reflectors, one or two dichroic reflectors per color and a mirror for one color, or one dichroic reflector for two colors and a mirror for one color, positioned within the beams (all three colors) 3509 diffracted outward by the expansion grating 3507 to reflect each color to a cover plate 3510 mounted on a molded substrate 3511. The light of each color is incident on the cover plate 3510 at different angles and across different regions of the cover plate 3510, and the light of the color is then refracted into the cover plate 3510 (and subsequently into the molded substrate 3511) at angles such that it is formed, for example, on the front surface 3512 of the molded substrate 3511 and then reflected by a low-index layer diffracted by three stacked gratings (one per color) 3513 mounted on the back surface 3514 of the molded substrate 3511. All three colors of light enter the array of reflective display devices 3515 at substantially the same angle for each color, and each color illuminates substantially the entire reflective area formed by one or more reflective display devices 3515. The reflective display devices reflect each color through the field grating 3513, through the molded substrate 3511, and onto a stack of three stacked display (e.g., LCoS) zero-order suppression (LZOS) gratings 3516 (one for each color) mounted on the front surface 3512 of the substrate 3511 (referred elsewhere herein to as redirection gratings, e.g., redirection gratings 3114, 3116, and 3118 in Figure 31A), causing the light to diffract outwards.

A portion of each color incident on the reflective display device 3515 is reflected to the display zero-order beam 3521, and a portion of each color incident on each display device (e.g., LCoS) is diffracted by each display device to the corresponding holographic light field 3522, e.g., holographic light fields 3220, 3222, and 3224 in Figure 32, which can be seen by the viewer. As discussed elsewhere in this specification, the display zero-order suppression grating (or redirection grating) 3516 is an angle-selective transmission grating that substantially diffracts light incident at the display zero-order angle but substantially transmits light incident at larger or smaller angles, separating the reflected display zero-order light from the diffracted holographic light field. The rejected display zero-order light 3523 can exit from the front of the redirection grating at a substantial angle, as shown in Figure 36B, or can be reflected by TIR or by the reflection grating to the molded substrate 3511, as described elsewhere in this specification.

In some embodiments, the tilt angle of the reflective elements 3508 can be adjusted to achieve greater uniformity of diffraction from the transmission field grating 3513 (e.g., by irradiating the transmission field grating 3513 at their regenerated Bragg angles or at angles close to their regenerated Bragg angles), and/or to achieve greater brightness of diffraction from the transmission field grating 3513 (e.g., by irradiating the transmission field grating 3513 at their regenerated Bragg angles or at angles close to their regenerated Bragg angles). Such adjustments can be made substantially independently for each color by adjusting the tilt angle of each of the reflective elements 3508.

In some embodiments, the adjustment can be performed as a one-time adjustment during manufacturing or assembly. Optionally, the adjustment can be performed by a user or installer in the field. In certain embodiments, the adjustment can be performed automatically as part of a feedback loop utilizing color and/or luminance sensors to detect and optimize optical properties of the holographic light field, such as luminance, uniformity, color uniformity, or white point. In some cases, the tilt angle of the reflective element 3508 perpendicular to the tilt angle shown in Figure 35B is adjusted to optimize the performance of the display system 3500. These approaches can be combined as needed.

In some cases, the tilt adjustment of the reflective element 3508 can be used to compensate for changes in the display system's components or alignment errors caused by factors such as manufacturing tolerances and assembly tolerances, vibrations and shocks during shipping, storage, and use, thermal expansion and contraction, degradation of the grid, laser diode, or other wavelength-dependent components, and wavelength shifts of the laser diode due to variations in operating temperature, operating duty cycle, and/or between components.

In some cases, by using substantially large or substantially small tilt adjustments of the reflective element 3508, for example, by tilting the molded substrate 3511 backward or forward, or by rotating it, the holographic light field can be tilted upward or downward, respectively, thereby maintaining alignment even if the angle between the expansion prism 3504 and the molded substrate 3511 is substantially changed from 90° (as shown in Figure 35B).

To achieve relatively uniform illumination on the reflective display 3515, the center of the beam from the laser diode can be offset, which also helps maintain color uniformity in the holographic light field. Slight differences in the paths each color travels to and from the display device 3515 (generally, mainly due to the color dispersion of the beam) can, for example, slightly shift the densities of the three colors when they are incident on the prism element 3504. This can also be corrected by adjusting the diffraction efficiency of the reflective display device 3515 in a spatially modified manner (e.g., by one or two dimensions). Since the diffraction efficiency is a function of the computer-generated hologram (CGH), such adjustments can be made immediately by utilizing elements with constant or adjustable spatially varying transmittance or absorbance before or after the display device 3515 (e.g., by one or two dimensions).

In some cases, the input light 3517 to the substrate 3511 (for example, as illustrated in Figure 36B) is p-polarized at the edge surface of the substrate 3511, and the input light 3517 enters the substrate 3511 (or the cover glass 3510, if used) to reduce Fresnel loss at the surface, or the surface can be tilted or an anti-reflective coating can be applied to reduce such Fresnel loss. A broadband half-wave retarder fixed on or behind the surface can convert such p-polarization to s-polarization if it is the required or desired polarization for the transmission field grating 3513.

In some cases, a broadband retarder positioned between the transmission field grating 3513 and the reflective display device 3515 can be used to further adjust the polarization of the light illuminating the reflective display device 3515 to provide the reflective display device 3515 with a required, desired, or optimal polarization state. Such a retarder can be fixed to the exit surface of the field grating 3513, or to the outer surface of the reflective display device 3515, or both, and may be a half-wave plate for providing p-polarization or s-polarization, or a quarter-wave plate for providing circular polarization, or may have a delay of a different value that can be varied spatially and/or temporally and/or wavelengthly to provide optimal polarization at every point on the reflective display device 3515 for each color. Insofar as such a wave plate provides a polarization state for the reflected holographic light field from the reflective display device 3515, this may not be the desired or optimal polarization state for subsequent polarization-dependent elements, such as the redirection grating 3516. In some cases, one or more additional waveplates can be provided before such elements or elements, having a constant, or spatially, temporally, or dye-varying delay, to further adjust the polarization to satisfy the elements or elements.

In some cases, the optical distance between the substrate 3511 and the coupled reflective element 3508 can be increased proportionally to allow the three colors of light to be further separated in their reflections by the reflective element 3508, so that each color is reflected by the corresponding reflective element without passing through one or two other reflective elements, or even separated enough for the three colors of light to be reflected using three mirrors without passing through other reflective elements.

In certain embodiments, the coupled reflector element 3508 can be positioned and tilted such that each illumination of the reflector element 3508 comes from substantially different directions, rather than from substantially optically coaxial laser beams. This allows the irradiator 3501S to be divided into two or three separate irradiators, each providing one or two of the three illumination colors, which may be less expensive and/or more efficient than using the optics within the irradiator 3501S to couple the light from the three laser diodes into a combined white input light providing the input light 3501.

In some embodiments, the molded substrate 3511 can be formed monolithically, for example, by computer numerical control (CNC) machining from a larger block of material, by optically combining or indexing two or more simpler (and therefore more manufacturable) shapes, or by additive or subtractive manufacturing techniques.

In certain embodiments, a reflective display 3515 (or an array of reflective display devices 3515) having a larger vertical range can be illuminated by increasing the height of the input light 3517, which is affected by the input light 3517 that actually enters the cover glass 3510 (optional) at the tip of the molded substrate 3511 forming a first lower cutoff for display illumination, and is affected by the input light 3517 that is missing from the corners 3518 of the molded substrate 3511 forming the upper and second lower cutoffs for display illumination.

In some embodiments, the illumination of the reflective display 3515 is at an angle of approximately 6°, which can be changed to approximately 0°, since the transmission field grating 3513 can also function as a zero-order suppression element similar to the redirection grating 3516. In such embodiments, the field grating 3513 can reflect, rather than transmit, the specularly reflected zero-order light from the reflective display 3515 within the shaped substrate 3511, and the TIR can direct it upward and from the top of the molded substrate 3511, or to an absorber 3524 formed thereon. Using the field grating 3513 in combination with the redirection grating 10016 at 0° or nearly 0° can reduce residual display zero-order light to a very high degree, for example, less than 2% or even <1%.

In certain embodiments, when a one-dimensional suppression grid is used, the zero-order suppression of the display appears not as a point, but as a dark band across the reflective display 3515, and the zero-order of each illuminated color is visible only as a point of that color within this dark band. If the viewer is more likely to view the reflective display 3515 from above rather than perpendicular to it, as is typically the case with a desktop or table display, the system may be configured to position the band above (but near, in angular space) the holographic light field, rather than below or to either side of it, where it is less likely to be noticed or undesirable. Similarly, if the viewer is more likely to view the display from below the normal or from below perpendicular to the reflective display 3515, the system may be configured to position the band below the holographic light field. If most viewers view the display using two eyes primarily dispersed horizontally, the band can be positioned above or below the holographic light field, instead of to the left or right.

In some embodiments, where the irradiator 3501S is derived from a light source having a spectral bandwidth on the order of several nanometers or tens of nanometers, diffraction in the expansion grating 3505 and field grating 3507 can spectrally disperse the incident illumination light onto the reflective display 3515. The illumination light can then exhibit spectral diversity (from the spectral bandwidth of the laser diode) and spatial diversity (from the dispersion of light from the laser diode by these gratings, and, to a smaller extent, from the light source size of the laser diode). These multiple orthogonality variabilities can result in a significant reduction in visible laser speckle in the holographic light field compared to that provided solely by the spectral and spatial diversity of the laser diode itself.

In some embodiments, the expansion grating 3505 can be formed with optical power such that it can completely or partially collimate the input light 3501 in one or two transverse directions, reducing or eliminating the need for laser diode collimation in the irradiator 3501S.

The incident angles of the input light 3517 to the cover plate 3510 may be selected such that two or more such incident angles are substantially equal. In this case, the number of reflective elements 3508 may be reduced, as a single reflective element may be sufficient to reflect two or more colors. Furthermore, the final reflective element in 3508 may be provided as a reflective coating on or within the substrate of a preceding reflective element, and this substrate may be wedge-shaped to provide different reflection angles to this final reflector.

The subject matter and functional operations described herein can be implemented in digital electronic circuits, specifically embodied computer software or firmware, computer hardware including the structures disclosed herein and their structural equivalents, or a combination of one or more of these. The subject matter described herein can be implemented as one or more computer programs, such as one or more modules of computer program instructions encoded on a tangible, non-temporary computer storage medium for execution by a data processing device or for controlling the operation of a data processing device. Alternatively or additionally, the program instructions can be encoded on artificially generated propagating signals, such as mechanically generated electrical signals, optical signals, or electromagnetic signals, which are generated to encode information for transmission to a suitable receiving device for execution by a data processing device. The computer storage medium may be a machine-readable memory device, a machine-readable memory board, a random or serial access memory device, or a combination of one or more of these.

The terms “data processing device,” “computer,” or “electronic computer device” (or equivalent as understood by those skilled in the art) refer to data processing hardware and encompass all kinds of devices, machines, and apparatus for processing data, including, for example, programmable processors, computers, or multiple processors or computers. Apparatus may also be, or further include, special-purpose logic circuits, such as central processing units (CPUs), FPGAs (field-programmable gate arrays), or ASICs (application-specific integrated circuits). In some implementations, data processing devices and special-purpose logic circuits may be hardware-based and software-based. Optionally, apparatus may include code that constitutes an execution environment for computer programs, such as processor firmware, protocol stacks, database management systems, operating systems, or a combination of one or more of these. This specification intends to describe the use of data processing devices with or without conventional operating systems.

A computer program, also known as a program, software, software application, module, software module, script, or code, can be written in any form of programming language, including compiled or interpreted languages, or declarative or procedural languages. It can be deployed as a standalone program or in any form, including modules, components, subroutines, or other units suitable for use in a computing environment. A computer program may, but is not required, correspond to a file in a file system. A program can be stored in other programs or data, for example, as part of a file holding one or more scripts stored in a markup language document, as a single file dedicated to the program in question, or as a set of coordinated files, for example, as a file storing one or more modules, subprograms, or parts of code. A computer program can be deployed to run on one or more computers located at one site or distributed across multiple sites and interconnected by a communication network. While parts of a program illustrated in various diagrams are shown as individual modules implementing various features and functions through various objects, methods, or other processes, a program may instead include several submodules, third-party services, components, libraries, etc., as needed. Conversely, the characteristics and functionalities of various components can be combined into a single component as needed.

The processes and logic flows described herein can be executed by one or more programmable computers that run one or more computer programs to perform their functions by manipulating input data and generating outputs. Processes and logic flows can also be executed and implemented as special-purpose logic circuits such as CPUs, GPUs, FPGAs, or ASICs.

A computer suitable for running computer programs can be based on a general-purpose or special-purpose microprocessor, both, or any other type of CPU. Generally, the CPU receives instructions and data from read-only memory (ROM) or random-access memory (RAM), or both. The main elements of a computer are the CPU for executing or running instructions, and one or more memory devices for storing instructions and data. Generally, a computer also includes, or is operably coupled to, one or more mass storage devices for storing data, such as magnetic disks, magneto-optical disks, or optical disks, to receive data from them, transfer data to them, or both. However, a computer is not required to have such devices. Furthermore, a computer can be embedded in another device, such as a mobile phone, personal digital assistant (PDA), mobile audio or video player, game console, global positioning system (GPS) receiver, or portable storage device, such as a Universal Serial Bus (USB) flash drive.

Computer-readable media (transient or non-transient as necessary) suitable for storing computer program instructions and data include, for example, all forms of non-volatile memory, media and memory devices, including semiconductor memory devices such as erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), and flash memory devices; magnetic disks such as internal hard disks or removable disks; magneto-optical disks; and CD-ROMs, DVD-Rs, DVD-RAMs, and DVD-ROM disks. Memory may store a variety of objects or data, including caches, lookup tables, classes, frameworks, applications, backup data, jobs, web pages, web page templates, database tables, repositories for storing business and dynamic information, and any other appropriate information, including any parameters, variables, algorithms, instructions, rules, constraints, or references. Furthermore, memory may include any other appropriate data, such as logs, policies, security or access data, report files, and others. Processors and memory may be complemented by or incorporated into special-purpose logic circuits.

To provide user interaction, the implementations of the subject matter described herein can be implemented on a computer having a display device for displaying information to the user, such as a cathode ray tube (CRT), liquid crystal display (LCD), light-emitting diode (LED), holographic or light field display, or plasma monitor, a keyboard and pointing device, such as a mouse, trackball, or trackpad, to which the user can provide input to the computer. Input can also be provided to the computer using a touchscreen, such as a pressure-sensitive tablet computer surface, a multi-touch screen using capacitive or electrosensory sensing, or other types of touchscreens. Other types of devices can similarly be used to provide user interaction; for example, feedback provided to the user may be any form of sensory feedback, such as visual feedback, auditory feedback, or haptic feedback, and input from the user may be received in any form, including acoustic, speech, or haptic input. In addition, the computer can interact with the user by, for example, sending a document to the user's device by sending a web page to the user's client device's web browser in response to a request received from a web browser, and then receiving the document from there.

The term “Graphical User Interface” or “GUI” may be used in the singular or plural form to describe one or more graphical user interfaces and each of the displays of a particular graphical user interface. Therefore, GUI can represent any graphical user interface, including but not limited to web browsers, touchscreens, or command-line interfaces (CLIs), that process information and efficiently present the results to the user. Generally, GUI may include some or all of the user interface (UI) elements associated with a web browser, such as interactive fields, pull-down lists, and buttons, that are operable by business suite users. These and other UI elements may be related to or represent the functionality of the web browser.

Implementations of the subject matter described herein can be implemented in a computing system that includes, for example, a data server, a backend component, or, for example, an application server, a middleware component, or a frontend component, such as a client computer having a graphical user interface or a web browser from which a user can interact with the implementation of the subject matter described herein, or one or more such combinations of backend components, middleware components, or frontend components. The components of the system can be interconnected by wired or wireless digital data communication, such as any form or medium of a communication network. Examples of communication networks include local area networks (LANs), wireless access networks (RANs), metropolitan area networks (MANs), wide area networks (WANs), global interoperability for microwave access (WiMAX), such as wireless local area networks (WLANs) using 902.11a/b/g/n and 902.20, all or part of the Internet, and any other communication systems in one or more locations. The network may communicate, for example, with Internet Protocol (IP) packets, Frame Relay frames, Asynchronous Transfer Mode (ATM) cells, voice, video, data, or other suitable information between network addresses.

A computing system can include clients and servers. Clients and servers generally interact with each other remotely, typically through a communication network. The relationship between clients and servers arises from computer programs running on each computer that have a client-server relationship with each other.

In some implementations, any or all components of a computing system, both hardware and software, may interface with each other or with an interface using an Application Programming Interface (API) or a service layer. An API may include specifications for routines, data structures, and object classes. An API may be independent of or dependent on a computer language, and may refer to an entire interface, a single function, or even a set of APIs. The service layer provides software services to the computing system. The functionality of various components of the computing system may be accessible to all service consumers through this service layer. Software services provide reusable and defined business functionality through a defined interface. For example, an interface may be software written in any preferred language that provides data in any preferred format. The API and service layer may be integrated or independent components in relation to other components of the computing system. Furthermore, any or all parts of the service layer may be implemented as a child or submodule of another software module, enterprise application, or hardware module without departing from the scope of this specification.

This specification includes many specific implementation details, but these should not be interpreted as limitations on the scope of any invention or claim, but rather as descriptions of features that may be specific to a particular implementation of a particular invention. Specific features described herein in the context of separate implementations may also be implemented in combination in a single implementation. Conversely, various features described in the context of a single implementation may also be implemented separately in multiple implementations or in any preferred sub-combinations. Furthermore, features may be described to act in a particular combination and initially claimed as such; however, in some cases, one or more features from a claimed combination may be removed from the combination, and the claimed combination may cover sub-combinations or variations of sub-combinations.

The specific implementations of the subject matter are described. Other implementations, modifications, and substitutions of the described implementations are within the following claims, as will be apparent to those skilled in the art. While the operations are shown in a specific order in the drawings or claims, this should not be understood as requiring that such operations be performed in a specific or sequential order shown, or that all illustrated operations be performed (some operations may be considered optional), in order to achieve the desired result. In certain circumstances, multitasking or parallel processing may be performed when deemed advantageous and appropriate.

For the sake of brevity, prior art for the structure, use, and/or similar of holographic gratings, LCOS devices, and other optical structures and systems may not be described in detail herein. Furthermore, the connecting lines shown in the various figures contained herein are intended to represent exemplary functional relationships, signal or optical paths, and/or physical couplings between various elements. It should be noted that many alternative or additional functional relationships, signal or optical paths, or physical connections may exist in exemplary holographic gratings, LCOS, or other optical structures or systems, and/or their components.

Detailed descriptions of the various exemplary embodiments described herein refer to the accompanying drawings and photographs illustrating various exemplary embodiments as illustrations. While these various exemplary embodiments are described in sufficient detail to enable those skilled in the art to implement the disclosure, it should be understood that other exemplary embodiments may be realized, and logical, optical, and mechanical modifications may be made without departing from the spirit and scope of the disclosure. Therefore, the detailed descriptions herein are presented for illustrative purposes only and are not limiting. For example, the steps described in either the method or process description may be performed in any preferred order and are not limited to the order presented unless expressly specified. Furthermore, any function or step may be outsourced to or performed by one or more third parties. Modifications, additions, or omissions may be made to the systems, apparatus, and methods described herein without departing from the scope of the disclosure. For example, components of systems and apparatus may be integrated or separated. Furthermore, the operation of the systems and apparatus disclosed herein may be performed by more, fewer, or other components, and the methods described may include more, fewer, or other steps.

As used herein, “each” refers to each member of a set or each member of a subset of a set. Furthermore, any reference to the singular may include multiple exemplary embodiments, and any reference to two or more components may include a single exemplary embodiment. While specific advantages are listed herein, various exemplary embodiments may include some, none, or all of the listed advantages.

Benefits, other advantages, and solutions to problems are described herein in relation to specific exemplary embodiments. However, benefits, advantages, solutions to problems, and any elements that cause or may cause any benefit, advantage, or solution to occur more prominently should not be construed as important, necessary, or essential features or elements of this disclosure. Therefore, the scope of this disclosure is not limited in any way to the appended claims, and references to singular elements, unless expressly indicated, are not intended to mean "one and only one," but rather "one or more." Furthermore, where phrases similar to "at least one of A, B, and C" or "at least one of A, B, or C" are used in the claims or specification, these phrases are intended to be construed as meaning that only A may be present in an exemplary embodiment, only B may be present in an exemplary embodiment, only C may be present in an exemplary embodiment, or any combination of elements A, B, and C, e.g., A and B, A and C, B and C, or A, B, and C, may be present in a single exemplary embodiment.

Therefore, the descriptions provided prior to the exemplary implementations do not define or limit this specification. Other modifications, substitutions, and replacements are also possible without departing from the spirit and scope of this specification.
Furthermore, it should be noted that the following embodiments are disclosed in this specification.
[Aspect 1]
An optical device,
The first optical diffraction component and
The second optical diffraction component,
A color-selective polarizer between the first optical diffraction component and the second optical diffraction component,
When a first light beam containing light of a first color in a first polarization state is incident on the first optical diffraction component, the first optical diffraction component diffracts the light of the first color in the first polarization state.
When a second light beam containing light of a second color in a second polarization state is incident on the color-selective polarizer, the color-selective polarizer converts the second light beam into a third light beam containing light of the second color in a first polarization state, wherein the second color is different from the first color, and the second polarization state is different from the first polarization state.
When the third light beam is incident on the second optical diffraction component, the second optical diffraction component diffracts the light of the second color in the first polarization state.
An optical device in which the diffraction efficiency of the first optical diffraction component for diffracting light of the second color in the second polarization state is substantially lower than the diffraction efficiency of the first optical diffraction component for diffracting light of the first color in the first polarization state. [Aspect 2]
An optical device,
The first optical diffraction component and
The second optical diffraction component,
A color-selective polarizer between the first optical diffraction component and the second optical diffraction component,
When light of a first color is incident on the first optical diffraction component at a first incidence angle and in a first polarization state, the first optical diffraction component diffracts the light of the first color at a first diffraction angle with a first diffraction efficiency.
When light of a second color, different from the light of the first color, is incident on the first optical diffraction component at a second incident angle in a second polarization state different from the first polarization state, the first optical diffraction component diffracts the light of the second color with a diffraction efficiency substantially lower than the first diffraction efficiency.
When light of the second color in the second polarization state is incident on the color-selective polarizer, the color-selective polarizer rotates the polarization state of the light of the second color from the second polarization state to the first polarization state.
An optical device wherein, when light of the second color is incident on the second optical diffraction component at the second incidence angle and in the first polarization state, the second optical diffraction component diffracts the light of the second color at the second diffraction angle with the second diffraction efficiency. [Aspect 3]
An optical device,
i) A first optical diffraction component configured to diffract light of a first color in a first polarization state incident at a first angle of incidence with a first diffraction angle and a first diffraction efficiency, and ii) a first optical diffraction component configured to diffract light of a second color in a second polarization state incident at a second angle of incidence with a diffraction efficiency substantially lower than the first diffraction efficiency,
A color-selective polarizer configured to rotate the polarization state of light of the second color in the second polarization state incident on the color-selective polarizer from the second polarization state to the first polarization state,
The system comprises a second optical diffraction component configured to diffract light of the second color in the first polarization state, incident at the second incidence angle, at a second diffraction angle and with a second diffraction efficiency,
An optical device in which the color-selective polarizer is located between the first optical diffraction component and the second optical diffraction component. [Aspect 4]
The second optical diffraction component is configured to diffract the light of the first color in the second polarization state at the first incident angle with a diffraction efficiency substantially lower than the second diffraction efficiency.
The optical device according to any one of the preceding embodiments, wherein the first optical diffraction component, the color-selective polarizer, and the second optical diffraction component are stacked sequentially, optionally, such that light of the first color and light of the second color are incident on the first optical diffraction component before the second optical diffraction component. [Aspect 5]
A third optical diffraction component,
The present invention further comprises a second color-selective polarizer between the second optical diffraction element and the third optical diffraction element,
The second color-selective polarizer is configured such that when light of a third color is incident on the second color-selective polarizer in the second polarization state, it rotates the polarization state of the light of the third color from the second polarization state to the first polarization state, and the third optical diffraction component is configured such that when light of the third color is incident on the third optical diffraction component at a third incidence angle and in the first polarization state, it diffracts the light of the third color at a third diffraction angle with a third diffraction efficiency.
The color-selective polarizer is configured to optionally rotate the polarization state of the light of the first color from the first polarization state to the second polarization state, and the second color-selective polarizer is configured to rotate the polarization state of the light of the second color from the first polarization state to the second polarization state without rotating the polarization state of the light of the first color.
A third color-selective polarizer configured to optionally rotate the polarization states of the first and second colored lights from a second polarization state to a first polarization state, without rotating the polarization state of the third colored light, wherein the third optical diffraction component further comprises a third color-selective polarizer located between the second color-selective polarizer and the third color-selective polarizer.
The third optical diffraction component is configured to diffract each of the first color light and the second color light incident in the second polarization state with a diffraction efficiency substantially lower than that of the third diffraction efficiency, the first optical diffraction component is configured to diffract the third color light incident in the second diffraction state with a diffraction efficiency substantially lower than that of the first diffraction efficiency, and the second optical diffraction component is configured to diffract each of the first color light and the third color light incident in the second polarization state with a diffraction efficiency substantially lower than that of the second diffraction efficiency.
Optionally, the second color-selective polarizer comprises a pair of first and second subpolarizers, wherein the first subpolarizer is configured to rotate the polarization state of the second color light from a first polarization state to a second polarization state without rotating the polarization states of the first and third color light respectively, and the second subpolarizer is configured to rotate the polarization state of the third color light from a second polarization state to a first polarization state without rotating the polarization states of the first and second color light respectively.
An optical device according to Embodiment 4, comprising a fourth color-selective polarizer configured to optionally rotate the polarization state of the first color of light from a second polarization state to a first polarization state without rotating the polarization states of the second color of light and the third color of light, wherein the first optical diffraction component further comprises a fourth color-selective polarizer located between the fourth color-selective polarizer and the color-selective polarizer. [Embodiment 6]
Each of the first optical diffraction component, the second optical diffraction component, and the third optical diffraction component comprises a holographic grating formed on the recording medium,
Optionally, the recording medium includes a photosensitive polymer.
Optionally, the recording medium is optically transparent.
Each of the holographic grids is optionally fixed to the recording medium.
Optionally, each of the first optical diffraction component, the second optical diffraction component, and the third optical diffraction component comprises a carrier film attached to the recording medium.
The optical device according to Embodiment 5, wherein each of the first optical diffraction component, the second optical diffraction component, and the third optical diffraction component optionally comprises a diffraction substrate attached to the other side of the recording medium opposite to the carrier film, wherein optionally the carrier film of the first optical diffraction component is attached to the first side of the color-selective polarizer, the diffraction substrate of the second optical diffraction component is attached to the second opposite side of the color-selective polarizer, the carrier film of the second optical diffraction component is attached to the first side of the second color-selective polarizer, and the diffraction substrate of the second optical diffraction component is attached to the second opposite side of the second color-selective polarizer. [Embodiment 7]
The circuit board is further equipped,
The first optical diffraction component is located between the substrate and the color-selective polarizer.
Optionally, the optical device further comprises an anti-reflective coating on the surface of the substrate.
Optionally, the optical device further comprises a front and a back,
The optical device according to any one of the prior embodiments, wherein light of the first color and light of the second color are optionally incident on the front surface, and the optical device further comprises an anti-reflective coating on the back surface. [Aspect 8]
The optical system comprises a plurality of optical components, including the first optical diffraction component, the color-selective polarizer, and the second optical diffraction component.
An optical device according to any one of the prior embodiments, wherein two adjacent optical components among the plurality of components are mounted together through a refractive index matching material. [Aspect 9]
Each of the first optical diffraction component and the second optical diffraction component comprises a Bragg grating formed in the recording medium,
Each of the Bragg grids is a plurality of fringe planes, with a fringe inclination angle θ perpendicular to the fringe planes within the volume of the recording medium. _t and comprising a plurality of fringe planes having a fringe spacing Λ,
Optionally, each of the Bragg gratings, when the angle of incidence to the recording medium is the on-Bragg angle, has a diffraction angle θ _{I understand} However, Bragg's formula mλ = 2 n Λ sin(θ) _{I understand} -θ _t It is configured to be filled with ), where λ represents the respective wavelengths of light of a certain color in a vacuum, n represents the refractive index in the recording medium, and θ _{I understand} However, this represents the m-th order Bragg angle of diffraction within the recording medium, θ _t However, this represents the fringe slope within the recording medium,
Optionally, the first incident angle and the second incident angle are substantially the same as the Onbragg angle, and the first diffraction angle and the second diffraction angle are substantially the same as the first Bragg angle.
Optionally, the fringe inclination angle of each of the Bragg grids is substantially the same as 45 degrees.
Optionally, the thickness of the recording medium is more than an order of magnitude larger than the fringe spacing.
Optionally, the thickness of the recording medium is approximately 30 times greater than the fringe spacing.
The first diffraction angle and the second diffraction angle are substantially the same,
Selectively, the first diffraction angle and the second diffraction angle are each in the range of -10 degrees to 10 degrees.
Optionally, each of the first diffraction angle and the second diffraction angle is substantially the same as 0 degrees.
Selectively, the first diffraction angle and the second diffraction angle are each in the range of -7 degrees to 7 degrees.
Optionally, the first diffraction angle and the second diffraction angle are substantially the same as 6 degrees.
Selectively, the first diffraction angle and the second diffraction angle are each in the range of 70 degrees to 90 degrees.
An optical device according to any one of the prior embodiments, wherein the first diffraction angle and the second diffraction angle are substantially the same as each other, optionally. [Aspect 10]
The first polarization state is s-polarization, and the second polarization state is p-polarization.
The first optical diffraction component is configured to diffract the second color light incident in the second polarization state with a diffraction efficiency at least one order of magnitude smaller than the first diffraction efficiency, and the color-selective polarizer is configured not to rotate the polarization state of the first color light, and
The optical device according to any one of the following is effective: the optical device is a second color-selective polarizer configured to rotate the polarization state of the light of the first color from a second polarization state to a first polarization state without rotating the polarization state of the light of the second color, and the first optical diffraction component further comprises a second color-selective polarizer located between the second color-selective polarizer and the color-selective polarizer. [Aspect 11]
The first optical diffraction component comprises a first diffraction structure, and the second optical diffraction component comprises a second diffraction structure.
The optical device comprises a first reflective layer and a second reflective layer, wherein the first reflective layer is located between the first diffraction structure and the second diffraction structure, and the second diffraction structure is located between the first reflective layer and the second reflective layer.
The first diffraction structure is configured to: i) diffract primary and zero-order light of the first color incident at a first incidence angle, wherein the primary light is diffracted at the first diffraction angle and the zero-order light is transmitted at the first incidence angle; and ii) transmit second color light incident at a second incidence angle to the first diffraction structure.
The first reflective layer is configured to: i) completely reflect light of the first color incident on the first reflective layer at the first angle of incidence, and ii) transmit light of the second color incident on the first reflective layer at the second angle of incidence.
The optical device according to any one of the prior embodiments, wherein the second diffraction structure is configured to diffract primary and zero-order light of the second color incident at a second incidence angle, the primary light is diffracted at a second diffraction angle, the zero-order light is transmitted at a second incidence angle, and the second reflective layer is configured to completely reflect the second color light incident at a second incidence angle. [Aspect 12]
An optical device,
A first optical diffraction component having a first diffraction structure,
A second optical diffraction component having a second diffraction structure,
The first reflective layer,
It comprises a second reflective layer,
The first reflective layer is located between the first diffraction structure and the second diffraction structure.
The second diffraction structure is located between the first reflective layer and the second reflective layer.
When light of a first color is incident on the first diffraction structure at a first angle of incidence, the first diffraction structure diffracts the first-order and zero-order light of the first color, the first-order light is diffracted at a first diffraction angle, and the zero-order light is transmitted at the first angle of incidence.
When light of a second color is incident on the first diffraction structure at a second incidence angle, the first diffraction grating transmits the light of the second color at the second incidence angle.
When light of the first color is incident on the first reflective layer at the first angle of incidence, the first reflective layer completely reflects the light of the first color.
When light of the second color is incident on the first reflective layer at the second angle of incidence, the reflective layer transmits the light of the second color at the second angle of incidence.
When light of the second color is incident on the second diffraction structure at the second incidence angle, the second diffraction structure diffracts the first-order and zero-order light of the second color, the first-order light is diffracted at the second diffraction angle, and the zero-order light is transmitted at the second incidence angle.
An optical device in which, when light of the second color is incident on the second reflective layer at the second angle of incidence, the second reflective layer completely reflects the light of the second color. [Aspect 13]
An optical device,
A first diffraction structure comprising a first optical diffraction component, wherein the first diffraction structure is configured to: i) diffract first-order and zero-order light of a first color incident at a first incidence angle, wherein the first-order light is diffracted at a first diffraction angle and the zero-order light is transmitted at the first incidence angle; and ii) transmit second-order light of a second color incident at a second incidence angle to the first diffraction structure;
i) a first reflective layer configured to completely reflect light of the first color incident on the first reflective layer at the first angle of incidence, and ii) a first reflective layer configured to transmit light of the second color incident on the first reflective layer at the second angle of incidence,
A second optical diffraction component comprising a second diffraction structure, wherein the second diffraction structure is configured to diffract primary and zero-order light of the second color incident at a second incidence angle, such that the primary light is diffracted at a second diffraction angle and the zero-order light is transmitted at the second incidence angle,
The device comprises a second reflective layer configured to completely reflect light of the second color incident on the second reflective layer at the second angle of incidence,
An optical device in which the first reflective layer is located between the first diffraction structure and the second diffraction structure, and the second diffraction structure is located between the first reflective layer and the second reflective layer. [Aspect 14]
An optical device,
A first optical diffraction component comprising a first diffraction structure configured to diffract light of a first color having a first incidence angle at a first diffraction angle,
A second optical diffraction component comprising a second diffraction structure configured to diffract light of a second color having a second incidence angle at a second diffraction angle,
A first reflective layer configured to completely reflect light of the first color having the first angle of incidence and to transmit light of the second color having the second angle of incidence,
A second reflective layer configured to completely reflect light of the second color having the second angle of incidence,
An optical device in which the first reflective layer is located between the first diffracting structure and the second diffracting structure, and the second diffracting structure is located between the first reflective layer and the second reflective layer. [Aspect 15]
The optical device further comprises a color-selective polarizer between the first diffraction structure and the second diffraction structure, wherein the first diffraction structure is configured to i) diffract light of the first color in a first polarization state incident at a first incidence angle with a first diffraction efficiency, and ii) diffract light of the second color in a second polarization state incident at a second incidence angle with a diffraction efficiency substantially lower than that of the first diffraction efficiency, wherein the color-selective polarizer is configured to rotate the polarization state of light of the second color in the second polarization state incident on the color-selective polarizer from the second polarization state to the first polarization state, and the second diffraction structure is configured to diffract light of the second color in the first polarization state incident at a second incidence angle with a second diffraction efficiency.
The optical device further comprises a side surface and a light absorber attached to the side surface and configured to absorb fully reflected light of the first and second colors.
The first reflective layer is configured to have a refractive index smaller than that of the layer of the first optical diffraction component directly adjacent to the first reflective layer, such that light of the first color having the first incident angle is completely reflected by the interface between the first reflective layer and the layer of the first optical diffraction component without completely reflecting light of the second color having the second incident angle.
The first optical diffraction component comprises a first carrier film and a first diffraction substrate attached to both sides of the first diffraction structure, wherein the first carrier film is closer to the second diffraction structure than the first diffraction substrate, and the first carrier film comprises the first reflective layer, and
The optical device according to any one of embodiments 12 to 14, wherein the second optical diffraction component comprises a second carrier film and a second diffraction substrate attached to both sides of the second diffraction structure, wherein at least one of the following is effective: the second diffraction substrate is closer to the first diffraction structure than the second carrier film, and the second reflective layer is attached to the second carrier film. [Embodiment 16]
A third optical diffraction component comprising a third diffraction structure, wherein the third diffraction structure is configured to diffract primary and zero-order light of a third color incident at a third incidence angle, the primary light is diffracted at a third diffraction angle, the zero-order light is transmitted at a third incidence angle, and the second reflection layer is located between the second diffraction structure and the third diffraction structure.
The first reflective layer and the second reflective layer are optionally configured to transmit light of the third color incident at the third incident angle.
Optionally, the optical device further comprises a third reflective layer configured to completely reflect light of the third color incident at the third angle of incidence, and the third diffraction structure is located between the second reflective layer and the third reflective layer.
The optical device according to any one of embodiments 12 to 15, wherein the second optical diffraction component comprises a second diffraction substrate and a second carrier film, optionally arranged on both sides of the second diffraction structure, and the third optical diffraction component comprises a third carrier film and a third diffraction substrate, positioned on both sides of the third diffraction structure, and the second reflective layer is located between the second carrier film and the third carrier film. [Embodiment 17]
Each of the first diffraction structure and the second diffraction structure comprises a holographic grating formed on a recording medium,
Optionally, the recording medium includes a photosensitive polymer.
Optionally, the recording medium is optically transparent.
Optionally, each of the first optical diffraction component and the second optical diffraction component comprises a Bragg grating formed on the recording medium, and each Bragg grating has a plurality of fringe planes, with a fringe inclination angle θ perpendicular to the fringe planes within the volume of the recording medium. _t and comprising a plurality of fringe planes having a fringe spacing Λ,
Optionally, each of the Bragg gratings, when the angle of incidence to the recording medium is the on-Bragg angle, has a diffraction angle θ _{I understand} However, Bragg's formula mλ = 2 n Λ sin(θ) _{I understand} -θ _t It is configured to be filled with ), where λ represents the respective wavelengths of light of a certain color in a vacuum, n represents the refractive index in the recording medium, and θ _{I understand} However, this represents the m-th order Bragg angle of diffraction within the recording medium, θ _t However, the fringe inclination within the recording medium is represented such that the first incident angle and the second incident angle are substantially the same as their respective On-Bragg angles, and the first diffraction angle and the second diffraction angle are substantially the same as their respective primary Bragg angles.
Optionally, the thickness of the recording medium is more than an order of magnitude larger than the fringe spacing.
Optionally, the thickness of the recording medium is approximately 30 times greater than the fringe spacing.
Selectively, the first diffraction angle and the second diffraction angle are substantially the same as each other.
Selectively, the first diffraction angle and the second diffraction angle are each in the range of -10 degrees to 10 degrees.
Optionally, the first diffraction angle and the second diffraction angle are substantially the same as 0 degrees.
An optical device according to any one of embodiments 12 to 16, wherein, optionally, each of the first diffraction angle and the second diffraction angle is substantially the same as 6 degrees. [Embodiment 18]
The first angle of incidence is different from the second angle of incidence,
Optionally, the light of the first color has a shorter wavelength than the light of the second color, and the first incident angle of the light of the first color is greater than the second incident angle of the light of the second color.
An optical device according to any one of embodiments 12 to 17, wherein the first angle of incidence and the second angle of incidence are optionally in the range of 70 degrees to 90 degrees. [Embodiment 19]
The device comprises a plurality of components including the first optical diffraction component and the second optical diffraction component, wherein two adjacent components among the plurality of components are attached together by an intermediate layer comprising at least one of a refractive index matching material, OCA, UV-curing optical adhesive or thermosetting optical adhesive, or optical contact material.
An optical device according to any one of embodiments 12 to 18, wherein the second reflective layer optionally comprises the intermediate layer. [Embodiment 20]
The first optical diffraction component further comprises a substrate having a back surface attached to the front surface of the first optical diffraction component,
The substrate is optionally configured to have a side surface that is angled relative to the back surface, and to receive light of multiple different colors on the side surface.
Optionally, the angle between the side surface and the back surface of the substrate is 90 degrees or more.
The substrate is optionally configured such that the plurality of different colored lights are incident on the side surface at substantially the same incident angle as 0 degrees.
An optical device according to any one of embodiments 12 to 19, wherein the substrate is optionally wedge-shaped, has an inclined front surface, and the angle between the front surface and the side surface is less than 90 degrees. [Embodiment 21]
It is a system,
An irradiator configured to provide light of multiple different colors,
The optical device described in any one of the embodiments 1 to 20,
A system in which the optical device is positioned adjacent to the irradiator and is configured to receive the plurality of different colored lights from the irradiator and to diffract the plurality of different colored lights. [Aspect 22]
The system according to embodiment 21, wherein the optical device is configured to diffract the plurality of different colored lights at diffraction angles that are substantially the same as each other, and each of the diffraction angles is optionally in the range of -10 degrees to 10 degrees. [Embodiment 23]
The system further includes a controller coupled to the irradiator and configured to control the irradiator to provide each of the plurality of different colored lights,
Optionally, the system further includes a display comprising a plurality of display elements, and the optical device is configured to diffract the plurality of colored lights toward the display.
Optionally, the controller is coupled to the display and configured to transmit respective control signals to each of the plurality of display elements for modulation of at least one characteristic of the display elements.
The system according to embodiment 21 or 22, wherein the controller is optionally configured to acquire graphic data including primitive data for a plurality of primitives corresponding to an object in three-dimensional space; determine the electromagnetic (EM) field contribution of each of the plurality of primitives to each of the plurality of display elements of the display for each of the plurality of primitives; generate the sum of the EM field contributions from the plurality of primitives to each of the plurality of display elements for each of the plurality of display elements; and generate the respective control signals for each of the plurality of display elements based on the sum of the EM field contributions to the display element. [Embodiment 24]
It is a system,
A display with multiple display elements,
The optical device described in any one of the embodiments 1 to 20,
A system in which the optical device is configured to diffract light of multiple different colors toward the display. [Aspect 25]
The optical device and the display are arranged along a certain direction, the optical device has a front and a back along the direction, the display has a front and a back along the direction, and the front of the display is spaced apart from the back of the optical device.
Optionally, the front surface of the display is separated from the back surface of the optical device by a gap.
Optionally, at least one of the front surface of the display or the back surface of the optical device is treated with an anti-reflective coating.
Optionally, the system further includes a transparent protective layer on the back surface of the optical device.
Optionally, the front of the display and the back of the optical device are attached together by an intermediate layer.
The intermediate layer is optionally configured to have a refractive index lower than that of the layer of the optical device, such that each of the plurality of colors of light transmitted in zero order by the optical device is completely reflected at the interface between the intermediate layer and the layer of the optical device.
Optionally, the system further includes a cover on the front surface of the display, and the optical device is formed within the cover glass.
The system according to embodiment 24, wherein the optical device is optionally configured to receive the plurality of colors of light on the front surface of the optical device. [Embodiment 26]
The optical device is configured to have a substrate in front of it and to receive the plurality of colors of light from at least one side of the substrate.
Optionally, the optical device comprises at least one diffraction grating supported by the substrate and configured to diffract the plurality of different colored lights toward the display,
The substrate optionally comprises a container filled with a liquid having a refractive index smaller than that of the recording medium of the diffraction grating.
Optionally, the substrate is wedge-shaped and has an inclined front surface.
Optionally, the angle between the front surface and the side surface is less than 90 degrees.
The optical device is optionally configured to receive different portions of the multiple different colored lights along different optical paths within the substrate, and to diffract the different portions to illuminate different corresponding areas of the display.
Optionally, the different regions comprise two or more of the lower region, upper region, left region, and right region of the display.
The different portions of the multiple different colored lights are optionally provided by different corresponding irradiators.
The optical device is optionally configured to receive different portions of the multiple different colored lights from different corresponding sides of the substrate.
The optical device is optionally configured to receive a first portion of the multiple different colored light from a first side surface of the substrate to the back surface of the optical device, diffract the first portion to illuminate a first area of the display, and receive a second portion of the multiple different colored light from a second side surface of the substrate to the front surface of the optical device, reflect the second portion backward against the back surface of the optical device, diffract the second portion to illuminate a second area of the display.
Optionally, the first aspect and the second aspect are the same aspect.
Optionally, the second portion of the multiple different colored lights is reflected by total internal reflection or a reflection grating within the optical device.
The system according to embodiment 24 or 25, wherein the substrate optionally includes a partially reflective surface configured to separate the input light into a first portion and a second portion. [Embodiment 27]
The optical device comprises at least one diffraction grating disposed on the back surface of the optical device,
The diffraction grating optionally comprises different subregions having different corresponding diffraction efficiencies.
The diffraction grating is configured to optionally diffract a first portion of the plurality of different colored lights incident on a first sub-region of the diffraction grating to illuminate a first region of the display, and further to reflect a second portion of the plurality of different colored lights, which are reflected backward from the back surface of the optical device and incident on a second sub-region of the diffraction grating, back to the front surface of the optical device, and to diffract the second portion to illuminate a second different region of the display.
The diffraction grating is optionally configured such that the diffracted first portion and the diffracted second portion on the first and second regions of the display have substantially the same optical power.
The system according to any one of embodiments 24 to 26, wherein the first region and the second region of the display optionally have different reflectances associated with a first different diffraction efficiency and a second different diffraction efficiency of the first sub-region and the second sub-region of the diffraction grating. [Embodiment 28]
The diffraction grating comprises a plurality of sub-regions that are tiled together,
The sub-region is optionally tiled along the horizontal direction.
The edges of the different sub-regions are optionally configured to contact each other in an optically seamless manner.
The different sub-regions are formed by including one or more edge-defining elements in at least one optical path of the recording beam or object beam when recording each sub-region on the recording medium, and the one or more edge-defining elements comprises a square aperture, a rectangular aperture, or a planar tile aperture.
Optionally, two adjacent sub-regions of the diffraction grating are in contact with the gap.
Optionally, the display comprises a plurality of tile-like display devices, and the gap between adjacent sub-regions of the diffraction grating is aligned with the gap between adjacent tile-like display devices of the display.
The system according to embodiment 27, wherein two adjacent and distinct sub-regions have an overlap, optionally. [Embodiment 29]
The diffraction grating is mechanically formed by using an embossed structure, a nanoimprinted structure, or a self-assembled structure, and
The system according to embodiment 27 or 28, wherein the display has a width along the horizontal direction and a height along the vertical direction, and at least one of the following is valid: the horizontal direction and the vertical direction are perpendicular to the direction, and the aspect ratio of the width to the height is greater than 16:9. [Embodiment 30]
The optical device is configured to diffract the plurality of different colored lights at diffraction angles that are substantially the same as each other.
Selectively, each of the diffraction angles is in the range of -10 degrees to 10 degrees.
The display is optionally configured to diffract the diffracted color light backward through the optical device,
The system according to any one of embodiments 24 to 29, wherein, optionally, a region of the optical device covers a region of the display. [Embodiment 31]
The present invention further includes an irradiator positioned adjacent to the optical device and configured to provide the optical device with light of the plurality of colors,
The irradiator optionally comprises a plurality of light-emitting elements, each configured to emit light of a different color.
The centers of the beams from the plurality of light-emitting elements are optionally offset from each other.
The irradiator is optionally configured to provide an optical beam having an elliptical beam profile or a rectangular beam profile.
The irradiator is optionally configured to provide a light beam with a specific polarization orientation.
The irradiator optionally comprises one or more optical components configured to independently control the ellipticity and polarization orientation of each of the plurality of different colored lights,
The irradiator optionally comprises one or more optical components configured to control the uniformity of the plurality of different colored lights,
Optionally, one or more of the optical components include an apodizing optical element or a profile converter.
The system according to any one of embodiments 24 to 30, wherein the system optionally includes one or more anamorphic optical elements or one or more cylindrical optical elements configured to increase the width of the multiple different colored lights. [Embodiment 32]
A prism element between the irradiator and the optical device, configured to receive the plurality of different colored lights from the input surface of the prism element,
The prism element comprises one or more expansion gratings adjacent to the exit surface, each of which is configured to expand the beam profile of light of different corresponding colors by a coefficient of at least one dimension.
Optionally, the system further includes one or more reflectors downstream of the one or more expansion diffraction gratings, each of the one or more reflectors configured to reflect light of a particular color to the optical device.
The tilt angle of each of the one or more reflectors can be optionally adjusted independently to cause uniformity of diffraction from the optical device to the display.
Optionally, the system further includes at least one of a color sensor or a luminance sensor configured to detect one or more optical properties of the holographic light field formed by the system, wherein the tilt angle of the one or more reflectors is adjustable based on the detected optical properties of the holographic light field.
Optionally, one or more of the optical properties include brightness uniformity, color uniformity, or a white point.
Optionally, one or more of the reflectors can be adjusted to compensate for changes in the alignment of the components of the system.
The optical distance between one or more reflectors and the optical device is optionally configured such that each of the multiple different colored lights is reflected by the corresponding reflector without transmission through one or more other reflectors.
The one or more reflectors are optionally configured such that the light emitted from each of the one or more reflectors comes from substantially different directions.
The angle between the prism element and the substrate of the optical device can be optionally adjusted to tilt the position of the holographic light field formed by the system.
The system according to embodiment 31, wherein, optionally, one or more extended gratings are configured to collimate the multiple different colored lights in one or two transverse directions, at least partially. [Embodiment 33]
The system further includes a controller coupled to the irradiator and configured to control the irradiator to provide each of the plurality of colors of light,
Optionally, the controller is coupled to the display and configured to transmit respective control signals to each of the plurality of display elements for modulation of at least one characteristic of the display elements.
The controller is configured to optionally acquire graphic data including primitive data for a plurality of primitives corresponding to an object in three-dimensional space, determine the electromagnetic (EM) field contribution of each of the plurality of primitives to each of the plurality of display elements of the display, generate the sum of the EM field contributions from the plurality of primitives to each of the plurality of display elements, and generate the respective control signals for each of the plurality of display elements based on the sum of the EM field contributions to the display element.
The controller is optionally configured to sequentially modulate the display with information associated with the plurality of colors of light over a series of periods, and to control the irradiator to sequentially emit each of the plurality of colors of light to the optical device during each period of the series of periods, such that each of the plurality of colors of light is diffracted toward the display by the optical device and reflected by the modulated display elements of the display to form a corresponding three-dimensional light field of each color for the object within each period.
The system according to embodiment 31 or 32, wherein the controller is optionally configured to modulate the display such that the respective three-dimensional color light fields appear i) entirely in front of the display, ii) entirely behind the display, or iii) partially in front of the display and partially behind the display. [Embodiment 34]
The display includes a spatial light modulator (SLM) which includes a digital micromirror device (DMD) or a liquid crystal on silicon (LCOS) device.
The system according to any one of embodiments 24 to 33, optionally further comprising an optical polarizer positioned between the display and the optical device, wherein the optical polarizer is configured to change the polarization state of the plurality of different colored lights. [Embodiment 35]
The optical device includes an optical diffraction component configured to diffract light containing a plurality of different colors toward the display, which is configured to diffract a portion of the light illuminating the display element,
The optical device further comprises an optical redirection component configured to optionally transmit the portion of the light to form a holographic scene and redirect the zero-order display light away from the holographic scene in three-dimensional (3D) space, wherein the zero-order display light includes reflected light from the display.
Optionally, the optical redirection component comprises a plurality of redirection holographic gratings for the display zero-order light of the plurality of different colored lights, and each of the plurality of redirection holographic gratings is configured to diffract the display zero-order light of each of the plurality of different colored lights in the 3D space in the respective direction and at the respective diffraction angles.
Optionally, the optical diffraction component diffracts the multiple different colored lights so as to redirect the zero-order light of the display reflected from the display away from the holographic scene, thereby making the display approximately zero. ^o It is configured to emit light at this angle,
Optionally, the ratio of the amount of display zero-order light in the holographic scene with suppression of the optical diffraction component and the optical redirection component to the amount of display zero-order light in the holographic scene without suppression is less than 2%.
The system according to any one of embodiments 24 to 34, wherein optionally the optical redirection component comprises a one-dimensional suppression grating, the holographic scene includes a band corresponding to the suppression of zero-order light of the display, and the system is configured such that the band is outside the viewer's field of view. [Embodiment 36]
It is a system,
A display with multiple display elements,
An optical device positioned adjacent to the display and configured to diffract light relative to the display,
The display is connected to the aforementioned display, and
This involves obtaining graphic data containing primitive data for each of the multiple primitives corresponding to an object in three-dimensional space,
For each of the plurality of primitives, the electromagnetic (EM) field propagation from the primitive to the display element is calculated in a three-dimensional coordinate system to determine the EM field contribution of the display to each of the plurality of display elements.
For each of the plurality of display elements, the sum of the EM field contributions from the plurality of primitives to the display element is generated,
A system comprising: a controller configured to transmit a control signal for each of the plurality of display elements, based on the sum of the EM field contributions to the display element, for the purpose of modulating at least one characteristic of the display element. [Aspect 37]
The optical device includes the optical device described in any one of embodiments 1 to 11, and
The system according to embodiment 36, wherein at least one of the following is effective: the optical device includes an optical device described in any one of embodiments 12 to 20. [Embodiment 38]
The optical device comprises a holographic grid formed on the recording medium.
The optical device comprises a plurality of holographic gratings formed on a recording medium, and each of the plurality of holographic gratings is configured to diffract light having a respective color and a respective angle of incidence to the display.
The optical device is positioned in front of the display, and the display is configured to diffract the diffracted light backward through the optical device to form a three-dimensional light field corresponding to the object, and
The system according to embodiment 36 or 37, wherein at least one of the following is effective: the optical device further comprises an irradiator positioned adjacent to the optical device and configured to provide light to the optical device. [Embodiment 39]
The aforementioned controller
The display is sequentially modulated with information associated with multiple colors corresponding to multiple colors of light over a series of periods,
The system according to embodiment 38, configured to control the irradiator so that each of the multiple colors of light is sequentially emitted to the optical device within each of the series of periods such that each of the multiple colors of light is diffracted by the optical device toward the display and reflected by the modulated display elements of the display to form a three-dimensional light field of each color corresponding to the object within each of the periods. [Embodiment 40]
It is a method,
A method comprising manufacturing an optical device as described in any one of embodiments 1 to 20. [Embodiment 41]
A method for manufacturing an optical device according to any one of the embodiments 1 to 11,
To form the first optical diffraction component,
To form the second optical diffraction component described above,
A method comprising arranging the color-selective polarizer between the first optical diffraction component and the second optical diffraction component. [Aspect 42]
Forming the first optical diffraction component includes forming a first diffraction structure on the recording medium.
Optionally, forming the first diffraction structure on the recording medium includes recording a first holographic grating on the recording medium by irradiating the recording medium with a first recording object beam at a first recording object angle and a first recording reference beam at a first recording reference angle, wherein the first recording object beam and the first recording reference beam have the same wavelength and the same first polarization state.
Optionally, the light of the first color is wider than or includes the same wavelength range as the first recording reference beam or the first recording object beam.
Optionally, the first recording reference beam corresponds to a color different from the first color of the first color of light,
Optionally, the first incident angle of the light of the first color is substantially the same as the first recording reference angle, and the first diffraction angle is substantially the same as the first recording object angle.
Optionally, the first recording reference angle is in the range of 70 degrees to 90 degrees.
Optionally, the first recording reference angle is in the range of 80 degrees to 90 degrees.
Optionally, the first recording object angle is in the range of -10 degrees to 10 degrees.
Optionally, the first recording object angle is substantially the same as 6 degrees.
Optionally, the first recording object angle is substantially the same as 0 degrees.
Optionally, the sum of the first recording reference angle and the first recording object angle is substantially the same as 90 degrees.
Optionally, the thickness of the recording medium is more than an order of magnitude greater than the wavelength of the first recording object beam.
Optionally, the thickness of the recording medium is approximately 30 times greater than the wavelength of the first recording object beam.
Optionally, forming the first diffraction structure on the recording medium includes fixing the first diffraction structure to the recording medium, and optionally, the recording medium is located between a carrier film and a diffraction substrate.
The first diffraction angle and the second diffraction angle are substantially the same,
The method according to embodiment 41, wherein the first diffraction angle and the second diffraction angle are optionally substantially the same as each other. [Embodiment 43]
Placing the color-selective polarizer between the first optical diffraction component and the second optical diffraction component is
The method includes sequentially stacking the first optical diffraction component, the color-selective polarizer, and the second optical diffraction component such that the light of the first color and the light of the second color are incident on the first optical diffraction component before the second optical diffraction component,
Selectively stacking the first optical diffraction component, the color-selective polarizer, and the second optical diffraction component includes sequentially arranging the first optical diffraction component, the color-selective polarizer, and the second optical diffraction component on a substrate in front of the first optical diffraction component.
The method according to embodiment 42, wherein the first optical diffraction component, the color-selective polarizer, and the second optical diffraction component are stacked sequentially in an optional manner, and the color-selective polarizer is attached to the first optical diffraction component through a first intermediate layer, and the second optical diffraction component is attached to the color-selective polarizer through a second intermediate layer, and each of the first intermediate layer and the second intermediate layer contains a refractive index matching material. [Embodiment 44]
To form a third optical diffraction component configured to diffract light of a third color having the first polarization state and the third incident angle at a third diffraction angle with a third diffraction efficiency,
The method includes arranging a second color-selective polarizer between the second optical diffraction component and the third optical diffraction component, wherein the second color-selective polarizer is configured to rotate the polarization state of the third color of light from the second polarization state to the first polarization state,
The color-selective polarizer is configured to optionally rotate the polarization state of the light of the first color from the first polarization state to the second polarization state, and the second color-selective polarizer is configured to rotate the polarization state of the light of the second color from the first polarization state to the second polarization state without rotating the polarization state of the light of the first color.
Optionally, the method further includes arranging a third color-selective polarizer in continuity with the third optical diffraction component such that the third optical diffraction component is between the second color-selective polarizer and the third color-selective polarizer, wherein the third color-selective polarizer is configured to rotate the polarization states of the first color light and the second color light, respectively, from a second polarization state to a first polarization state without rotating the polarization state of the third color light.
The method according to any one of embodiments 41 to 43, optionally further comprising arranging a fourth color-selective polarizer in front of the first optical diffraction component such that the first optical diffraction component is between the fourth color-selective polarizer and the color-selective polarizer, wherein the fourth color-selective polarizer is configured to rotate the polarization state of the light of the first color from a second polarization state to a first polarization state without rotating the polarization states of the light of the second color and the light of the third color, respectively. [Embodiment 45]
The method according to any one of embodiments 41 to 44, wherein the first polarization state is s-polarized and the second polarization state is p-polarized. [Embodiment 46]
A method for manufacturing an optical device according to any one of embodiments 12 to 20,
To form the first optical diffraction component having the first diffraction structure,
To form the second optical diffraction component having the second diffraction structure,
The first reflective layer is arranged between the first diffraction structure and the second diffraction structure, wherein the second diffraction structure is arranged to be continuous with the first diffraction structure along a certain direction.
A method comprising arranging the second reflective layer in a manner continuous with the second diffraction structure along the aforementioned direction. [Aspect 47]
The invention further includes forming a light absorber on the side surface of the optical device, wherein the light absorber is configured to absorb the completely reflected light of the first and second colors.
The first reflective layer is configured to have a refractive index smaller than that of the layer of the first optical diffraction component directly adjacent to the first reflective layer, such that light of the first color having the first incident angle is completely reflected by the interface between the first reflective layer and the layer of the first optical diffraction component without completely reflecting light of the second color having the second incident angle.
Optionally, the method further includes forming a third optical diffraction component comprising a third diffraction structure configured to diffract light of a third color having a third angle of incidence, wherein arranging the second reflective layer continuously with respect to the second diffraction structure along the direction includes arranging the second reflective layer between the second diffraction structure and the third diffraction structure along the direction, wherein each of the first and second reflective layers is configured to transmit light of the third color having a third angle of incidence.
Optionally, the method further includes arranging a third reflective layer in a manner continuous with the third diffraction structure along the direction, wherein the third reflective layer is configured to completely reflect light of the third color having the third angle of incidence.
The method according to embodiment 46, wherein each of the first optical diffraction component, the second optical diffraction component, and the third optical diffraction component optionally comprises its own carrier film and its own diffraction substrate, the first reflective layer comprises the first carrier film of the first optical diffraction component, and arranging the first reflective layer between the first diffraction structure and the second diffraction structure includes attaching the second diffraction substrate of the second optical diffraction component to the first carrier film of the first optical diffraction component by a first intermediate layer, arranging the second reflective layer between the second diffraction structure and the third diffraction structure along the direction includes attaching the second carrier film of the second optical diffraction component to the third carrier film of the third optical diffraction component by a second intermediate layer, the second reflective layer comprises the second intermediate layer, and the third reflective layer is attached to the third diffraction substrate of the third optical diffraction component. [Embodiment 48]
Placing the first optical diffraction component on a substrate located in front of the first optical diffraction component in the aforementioned direction, further comprising the arrangement such that the substrate has a front and a back surface,
Optionally, arranging the first optical diffraction component on the substrate includes attaching the front surface of the first optical diffraction component to the back surface of the substrate through a refractive index matching material.
Optionally, the substrate has a side surface that is angled relative to the back surface of the substrate, and the substrate is configured to receive light of multiple different colors on the side surface.
The method according to embodiment 47, wherein the substrate is optionally configured such that the plurality of different colored lights are incident on the side surface at an incident angle substantially the same as 0 degrees. [Embodiment 49]
Forming the first optical diffraction component having the first diffraction structure includes forming the first diffraction structure on the recording medium.
Optionally, forming the first diffraction structure on the recording medium includes recording a first holographic grating on the recording medium by incidenting a first recording object beam at a first recording object angle and a first recording reference beam at a first recording reference angle, wherein the first recording object beam and the first recording reference beam have the same wavelength and the same polarization state.
Optionally, the light of the first color may be wider than or have the same wavelength range as the first recording reference beam.
Optionally, the first recording reference beam corresponds to a color different from the first color of the first color of light,
Optionally, the first incident angle of the light of the first color is substantially the same as the first recording reference angle, and the first diffraction angle is substantially the same as the first recording object angle.
Optionally, the first recording reference angle is in the range of 70 degrees to 90 degrees.
Optionally, the first recording reference angle is in the range of 70 to 80 degrees.
Optionally, the first recording object angle is in the range of -10 degrees to 10 degrees.
Optionally, the thickness of the recording medium is two orders of magnitude greater than the wavelength of the first recording object beam.
Optionally, the thickness of the recording medium is approximately 30 times greater than the wavelength of the first recording object beam.
The method according to any one of embodiments 46 to 48, wherein optionally forming the first diffraction structure on the recording medium includes fixing the first diffraction structure to the recording medium. [Embodiment 50]
The first angle of incidence is different from the second angle of incidence,
The method according to any one of embodiments 46 to 49, wherein optionally, the light of the first color has a shorter wavelength than the light of the second color, and the first angle of incidence is greater than the second angle of incidence. [Embodiment 51]
It is a method,
Forming an optical device according to the method described in any one of the embodiments 40 to 50,
A method comprising arranging the optical device and a display comprising a plurality of display elements such that the optical device is configured to diffract a plurality of different colored lights toward the display. [Aspect 52]
Arranging the optical device and the display includes separating the back surface of the optical device from the front surface of the display by a gap, and optionally further including forming an anti-reflective coating on at least one of the front surface of the display or the back surface of the optical device.
Arranging the optical device and the display involves mounting the back surface of the optical device onto the front surface of the display through an intermediate layer, and optionally the intermediate layer is configured to have a refractive index lower than that of the layer of the optical device such that each of the plurality of different colored lights transmitted in zero order by the optical device is completely reflected at the interface between the intermediate layer and the layer of the optical device.
The optical device is configured to diffract the plurality of different colored lights at diffraction angles that are substantially identical to each other, and optionally, each of the diffraction angles is in the range of -10 degrees to 10 degrees.
The display is configured to diffract the diffracted color light backward through the optical device.
The region of the optical device covers the region of the display, and
The method according to embodiment 51, wherein at least one of the following is effective: the optical device is configured to have a substrate in front of the optical device and to receive the plurality of different colored lights on a side of the substrate that is angled with respect to the back surface of the substrate. [Embodiment 53]
It is a method,
This involves using an optical device to convert an incident beam containing light of multiple different colors into light of individually diffracted colors.
A method wherein the optical device comprises the optical device described in any one of embodiments 1 to 20. [Embodiment 54]
It is a method,
The optical device transmits at least one timing control signal to an irradiator to activate the irradiator and emit the multiple different colored lights to the optical device, so that the irradiator converts multiple different colored lights into individually diffracted colored lights and irradiates a display comprising multiple display elements, wherein the optical device comprises the optical device described in any one of embodiments 1 to 20.
A method comprising: modulating the display elements by transmitting at least one respective control signal to each of the plurality of display elements of the display, such that the light of each individually diffracted color is reflected by the modulated display elements to form a multicolor three-dimensional light field corresponding to each of the respective control signals. [Aspect 55]
This involves obtaining graphic data containing primitive data for each of the multiple primitives corresponding to an object in three-dimensional space,
For each of the plurality of primitives, the electromagnetic (EM) field propagation from the primitive to the display element is calculated in a three-dimensional coordinate system to determine the EM field contribution of the display to each of the plurality of display elements.
For each of the plurality of display elements, the sum of the EM field contributions from the plurality of primitives to the display element is generated,
For each of the plurality of display elements, the respective control signals are generated based on the sum of the EM field contributions to the display element in order to modulate at least one characteristic of the display element.
The aforementioned multicolor three-dimensional light field corresponds to the object,
Optionally, the method includes sequentially modulating the display with information associated with a plurality of different colors over a series of periods, and controlling the irradiator to sequentially emit each of the plurality of colors of light to the optical device within each period of the series of periods, such that each of the light of the plurality of different colors is diffracted by the optical device toward the display and reflected by the modulated display elements of the display to form a respective color three-dimensional light field corresponding to the object within each period.
Selectively, the multiple different colored lights are diffracted by the optical device with respect to the display at substantially the same diffraction angle.
Selectively, the diffraction angle is in the range of -10 degrees to 10 degrees.
The irradiator and the optical device are optionally configured such that the plurality of different colored lights are incident on the first optical diffraction component of the optical device at their respective incident angles.
Selectively, each of the aforementioned angles of incidence is different from one another.
Selectively, the respective angles of incidence are substantially the same as each other.
The method according to embodiment 54, wherein each of the aforementioned angles of incidence is optionally in the range of 70 degrees to 90 degrees. [Embodiment 56]
An optical device,
At least two optical diffraction components,
A system comprising at least one color-selective polarizer,
An optical device configured such that when light of different colors is incident upon the optical device, the optical device separates the individual lights of the different colors while suppressing crosstalk between the different colors. [Aspect 57]
The optical device is configured such that when light of different colors is incident on the optical device, each of the optical diffraction components diffracts the light of each of the different colors.
The optical device is optionally configured such that, in the output light beam diffracted by the optical device, the power of a particular color of light among the different colors is at least an order of magnitude higher than the power of one or more other colors of light among the different colors.
The optical device according to embodiment 56, wherein the at least one color-selective polarizer is configured to optionally rotate the polarization state of at least one of the different colors such that light of a specific color among the different colors is incident on each of the optical diffraction components in a first polarization state, while light of one or more other colors among the different colors is incident on each of the optical diffraction components in a second polarization state different from the first polarization state. [Embodiment 58]
An optical device,
At least two optical diffraction components,
It comprises at least one reflective layer,
The optical device is configured such that when light of different colors is incident on the optical device, the optical device separates the light of each of the different colors while suppressing crosstalk between the different colors.
An optical device in which the at least one reflective layer is configured for total internal reflection of at least one of the different colors of light. [Aspect 59]
The optical device is configured such that the output light beam diffracted by the optical device contains only light of a specific color among the different colors, without crosstalk from one or more other colors among the different colors.
Optionally, the at least one reflective layer is configured to completely reflect zero-order light of a specific color among the different colors transmitted by each of the optical diffraction components, while transmitting one or more other colors among the different colors.
The optical device according to embodiment 58, wherein, optionally, when light of different colors is incident on the optical device, each of the optical diffraction components is configured to diffract the light of each of the different colors. [Embodiment 60]
It is a system,
The display and
The optical device comprises the optical device described in any one of embodiments 56 to 59,
A system in which the optical device is configured to diffract light of multiple different colors toward the display. [Aspect 61]
It is a system,
An irradiator configured to provide light of multiple different colors,
The optical device comprises the optical device described in any one of embodiments 56 to 59,
A system in which the optical device is configured to diffract the plurality of different colored lights from the irradiator. [Aspect 62]
It is a system,
The display and
A system comprising: an optical device having one or more transmission diffraction structures for diffracting light toward the display; [Aspect 63]
The display is a reflective display configured to diffract the light backward through the optical device,
The system according to embodiment 62, wherein the system optionally further comprises an irradiator configured to provide the light to the optical device, the irradiator being positioned in front of the transmission diffraction structure of the optical device. [Embodiment 64]
The display is a transmissive display configured to diffract the light forward without passing it through the optical device,
The system according to embodiment 62, wherein the system optionally further comprises an irradiator configured to provide the light to the optical device, the irradiator being located behind the transmission diffraction structure of the optical device. [Embodiment 65]
Each of the one or more transmission diffraction structures is configured to diffract each of the multiple different colors, and
The system according to any one of embodiments 62 to 64, wherein at least one of the following is effective: the optical device further comprises one or more reflection diffraction structures, and each of the one or more transmission diffraction structures and the one or more reflection diffraction structures is configured to diffract each of a plurality of different colors. [Embodiment 66]
It is a system,
The display and
A system comprising: an optical device having one or more reflection-diffraction structures for diffracting light toward the display; [Aspect 67]
The display is a reflective display configured to diffract the light backward through the optical device,
The system according to embodiment 66, wherein the system optionally further comprises an irradiator configured to provide the light to the optical device, the irradiator being located behind the reflection diffraction structure of the optical device. [Embodiment 68]
The display is a transmissive display configured to diffract the light forward without passing it through the optical device,
The system according to embodiment 66, wherein the system optionally further comprises an irradiator configured to provide the light to the optical device, the irradiator being positioned in front of the reflection diffraction structure of the optical device. [Embodiment 69]
Each of the one or more reflection diffraction structures is configured to diffract each of the multiple different colors, and
The system according to any one of embodiments 66 to 68, wherein at least one of the following is effective: the optical device further comprises one or more transmission diffraction structures, and each of the one or more transmission diffraction structures and the one or more reflection diffraction structures is configured to diffract each of a plurality of different colors. [Embodiment 70]
An optical device,
The optical diffraction component comprises a plurality of optical diffraction elements, each having at least one transmission diffraction structure and at least one reflection diffraction structure.
The optical device is configured such that when light of different colors is incident on the optical device, it separates the individual lights of the different colors while suppressing crosstalk between the different colors. [Aspect 71]
Each of the transmission diffraction structure and the reflection diffraction structure is configured to diffract light of each of the different colors.
Optionally, the optical device further comprises at least one reflective layer configured for the total internal reflection of at least one of the different colors of light,
The optical device according to embodiment 70, further comprising at least one color-selective polarizer configured to optionally rotate the polarization state of at least one of the different colors of light such that light of a specific color among the different colors is incident on each of the optical diffraction components in a first polarization state, while light of one or more other colors among the different colors is incident on each of the optical diffraction components in a second polarization state different from the first polarization state. [Embodiment 72]
It is a system,
The display and
The optical device comprises the optical device described in embodiment 70 or embodiment 71,
A system in which the optical device is configured to diffract light of multiple different colors toward the display. [Aspect 73]
It is a system,
An irradiator configured to provide light of multiple different colors,
The optical device comprises the optical device described in embodiment 70 or embodiment 71,
A system in which the optical device is configured to diffract the plurality of different colored lights from the irradiator. [Aspect 74]
An optical device,
An optical device comprising at least two beam expanders configured to generate an output light beam by diffracting an input light beam and adjusting the beam size of the input light beam of at least two dimensions. [Aspect 75]
The beam size includes width and height,
Optionally, each of the at least two beam expanders comprises its respective optical diffraction device.
The input light beam is optionally configured to contain light of multiple different colors, and each optical diffraction device is configured to diffract the light of multiple different colors at substantially identical diffraction angles.
The optical diffraction device is optionally configured such that, when light of different colors is incident upon it, the optical diffraction device separates the individual light of the different colors while suppressing crosstalk between the different colors.
Optionally, each of the optical diffraction devices comprises at least two optical diffraction components and at least one color-selective polarizer.
Optionally, each of the optical diffraction devices comprises at least two optical diffraction components and at least one reflective layer, wherein the at least one reflective layer is configured for total internal reflection of light of at least one color.
The optical device according to embodiment 74, wherein each of the optical diffraction devices optionally comprises at least one of one or more transmission diffraction structures or one or more reflection diffraction structures. [Embodiment 76]
The at least two beam expanders described above,
A first one-dimensional beam expander configured to expand the input light beam of a first dimension among the at least two dimensions to generate an intermediate light beam,
The system comprises a second one-dimensional beam expander configured to expand the intermediate light beam of a second dimension of the at least two dimensions to generate the output light beam,
The intermediate light beam has a beam size larger than the input light beam of the first dimension and the same beam size as the input light beam of the second dimension, and the output light beam has a beam size larger than the intermediate light beam of the second dimension and the same beam size as the intermediate light beam of the first dimension.
The optical device is optionally configured to couple the intermediate light beam from the first one-dimensional beam expander to the second one-dimensional beam expander using at least one of free-space aerial geometry, a monolithic substrate or a segmented substrate, or one or more coupling elements.
The optical device according to embodiment 74 or 75, wherein the intermediate input beam optionally includes collinear collimated light of two or more colors, and one or more coupling elements are configured to convert the collinear collimated light of two or more colors into two or more independent collimated but non-collinear light beams having corresponding colors of the two or more colors.

Claims (36)

An optical device,
The first optical diffraction component,
The second optical diffraction component,
A color-selective polarizer between the first optical diffraction component and the second optical diffraction component,
When a first light beam containing light of a first color in a first polarization state is incident on the first optical diffraction component at a first incidence angle , the first optical diffraction component diffracts the light of the first color in the first polarization state at a first diffraction angle with a first diffraction efficiency .
When a second light beam containing light of a second color in a second polarization state is incident on the color-selective polarizer, the color-selective polarizer converts the second light beam into a third light beam containing light of the second color in a first polarization state, wherein the second color is different from the first color, and the second polarization state is different from the first polarization state.
When the third light beam is incident on the second optical diffraction component at a second incidence angle , the second optical diffraction component diffracts the light of the second color in the first polarization state at a second diffraction angle with a second diffraction efficiency .
The diffraction efficiency of the first optical diffraction component that diffracts light of the second color in the second polarization state is smaller than the diffraction efficiency of the first optical diffraction component that diffracts light of the first color in the first polarization state.
An optical device in which the first optical diffraction component and the second optical diffraction component include corresponding transmission gratings for light of the first color and light of the second color . An optical device,
The first optical diffraction component and
The second optical diffraction component,
A color-selective polarizer between the first optical diffraction component and the second optical diffraction component,
When light of a first color is incident on the first optical diffraction component at a first incidence angle and in a first polarization state, the first optical diffraction component diffracts the light of the first color at a first diffraction angle with a first diffraction efficiency.
When light of a second color, different from the light of the first color, is incident on the first optical diffraction component at a second incident angle in a second polarization state different from the first polarization state, the first optical diffraction component diffracts the light of the second color with a diffraction efficiency lower than the first diffraction efficiency.
When light of the second color in the second polarization state is incident on the color-selective polarizer, the color-selective polarizer rotates the polarization state of the light of the second color from the second polarization state to the first polarization state.
When light of the second color is incident on the second optical diffraction component at the second incidence angle and in the first polarization state, the second optical diffraction component diffracts the light of the second color at the second diffraction angle with the second diffraction efficiency .
An optical device in which the first optical diffraction component and the second optical diffraction component include corresponding transmission gratings for light of the first color and light of the second color . An optical device,
i) A first optical diffraction component configured to diffract light of a first color in a first polarization state incident at a first angle of incidence with a first diffraction angle and a first diffraction efficiency, and ii) a first optical diffraction component configured to diffract light of a second color in a second polarization state incident at a second angle of incidence with a diffraction efficiency lower than the first diffraction efficiency,
A color-selective polarizer, configured to rotate the polarization state of light of a second color in a second polarization state incident on the color-selective polarizer from the second polarization state to the first polarization state,
The system comprises a second optical diffraction component configured to diffract light of the second color in the first polarization state, incident at the second incidence angle, at a second diffraction angle and with a second diffraction efficiency,
The color-selective polarizer is located between the first optical diffraction component and the second optical diffraction component.
An optical device in which the first optical diffraction component and the second optical diffraction component include corresponding transmission gratings for light of the first color and light of the second color . The optical device according to any one of claims 1 to 3, wherein the second optical diffraction component is configured to diffract light of the first color in the second polarization state at the first incident angle with a diffraction efficiency lower than the second diffraction efficiency. The optical device according to claim 4, wherein the first optical diffraction component, the color-selective polarizer, and the second optical diffraction component are sequentially stacked such that light of the first color and light of the second color are incident on the first optical diffraction component before the second optical diffraction component. A third optical diffraction component,
The present invention further comprises a second color-selective polarizer between the second optical diffraction element and the third optical diffraction element,
The optical device according to claim 4 or 5, wherein the second color-selective polarizer is configured to rotate the polarization state of the light of the third color from a second polarization state to a first polarization state when light of the third color is incident on the second color-selective polarizer in a second polarization state, and the third optical diffraction component is configured to diffract the light of the third color at a third diffraction angle with a third diffraction efficiency when light of the third color is incident on the third optical diffraction component at a third incidence angle and in a first polarization state. The color-selective polarizer is configured to rotate the polarization state of the light of the first color from the first polarization state to the second polarization state, and the second color-selective polarizer is configured to rotate the polarization state of the light of the second color from the first polarization state to the second polarization state without rotating the polarization state of the light of the first color, and/or
A third color-selective polarizer configured to rotate the polarization states of the first and second colored lights from a second polarization state to a first polarization state without rotating the polarization state of the third colored light, wherein the third optical diffraction component further comprises a third color-selective polarizer located between the second color-selective polarizer and the third color-selective polarizer, and/or
The third optical diffraction component is configured to diffract each of the light of the first color and the light of the second color incident in the second polarization state with a diffraction efficiency lower than the third diffraction efficiency, the first optical diffraction component is configured to diffract the light of the third color incident in the second diffraction efficiency with a diffraction efficiency lower than the first diffraction efficiency, the second optical diffraction component is configured to diffract each of the light of the first color and the light of the third color incident in the second polarization state with a diffraction efficiency lower than the second diffraction efficiency, and/or
The second color-selective polarizer comprises a pair of first and second subpolarizers, wherein the first subpolarizer is configured to rotate the polarization state of the second color light from a first polarization state to a second polarization state without rotating the polarization states of the first and third color light respectively, and the second subpolarizer is configured to rotate the polarization state of the third color light from a second polarization state to a first polarization state without rotating the polarization states of the first and second color light respectively, and/or
The optical device according to claim 6, wherein the optical device is a fourth color-selective polarizer configured to rotate the polarization state of the first color of light from a second polarization state to a first polarization state without rotating the polarization states of the second color of light and the third color of light, and the first optical diffraction component further comprises a fourth color-selective polarizer located between the fourth color-selective polarizer and the color-selective polarizer. The optical device according to claim 6 or 7 , wherein each of the first optical diffraction component, the second optical diffraction component, and the third optical diffraction component comprises a holographic grating formed on a recording medium. The recording medium includes a photosensitive polymer and/or
The recording medium is optically transparent and/or
Each of the holographic grids is fixed to the recording medium and/or
Each of the first optical diffraction component, the second optical diffraction component, and the third optical diffraction component comprises a carrier film attached to the recording medium and/or
Each of the first optical diffraction component, the second optical diffraction component, and the third optical diffraction component comprises a diffraction substrate attached to the other side of the recording medium opposite to the carrier film, and/or
The optical device according to claim 8, wherein the carrier film of the first optical diffraction component is attached to the first side of the color-selective polarizer, the diffraction substrate of the second optical diffraction component is attached to the second opposite side of the color-selective polarizer, the carrier film of the second optical diffraction component is attached to the first side of the second color-selective polarizer, and the diffraction substrate of the second optical diffraction component is attached to the second opposite side of the second color-selective polarizer. The circuit board is further equipped,
The optical device according to any one of claims 1 to 9 , wherein the first optical diffraction component is located between the substrate and the color-selective polarizer. The optical device further comprises an anti-reflective coating on the surface of the substrate and/or
The optical device further comprises a front and a back, and/or
The light of the first color and the light of the second color are incident on the front surface, and the optical device further comprises an anti-reflective coating on the back surface and/or
The optical device comprises a plurality of optical components, including the first optical diffraction component, the color-selective polarizer, and the second optical diffraction component, and/or
The optical device according to claim 10, wherein two adjacent optical components among the plurality of components are mounted together through a refractive index matching material. Each of the first optical diffraction component and the second optical diffraction component comprises a Bragg grating formed in the recording medium,
The optical device according to any one of claims 1 to 3, wherein each Bragg grid comprises a plurality of fringe planes, each having a fringe inclination angle θt and a fringe spacing Λ perpendicular to the fringe planes within the volume of the recording medium. When the angle of incidence to the recording medium is the on-Bragg angle, each Bragg grating satisfies Bragg's equation mλ = 2 n Λ sin(θm - θt).
It is configured such that, in the formula, λ represents the respective wavelengths of light of a certain color in a vacuum, n represents the refractive index in the recording medium, θm represents the m-th order Bragg angle of diffraction in the recording medium, θt represents the fringe slope in the recording medium, and/or
The first incident angle and the second incident angle are each the same as the On-Bragg angle, and the first diffraction angle and the second diffraction angle are each the same as the primary Bragg angle, and/or
The fringe inclination angle of each of the Bragg grids is the same as 45 degrees, and/or
The thickness of the recording medium is more than an order of magnitude greater than the fringe spacing, and/or
The thickness of the recording medium is 30 times greater than the fringe spacing, and/or
The first diffraction angle and the second diffraction angle are the same as each other, and/or
The first diffraction angle and the second diffraction angle are each in the range of -10 degrees to 10 degrees, and/or
The first diffraction angle and the second diffraction angle are both the same as 0 degrees, and/or
The first diffraction angle and the second diffraction angle are each in the range of -7 degrees to 7 degrees, and/or
The first diffraction angle and the second diffraction angle are both the same as 6 degrees, and/or
The first diffraction angle and the second diffraction angle are each in the range of 70 degrees to 90 degrees, and/or
The optical device according to claim 12, wherein the first diffraction angle and the second diffraction angle are the same as each other. The first polarization state is s-polarization, and the second polarization state is p-polarization.
The first optical diffraction component is configured to diffract the second color light incident in the second polarization state with a diffraction efficiency at least one order of magnitude smaller than the first diffraction efficiency, and the color-selective polarizer is configured not to rotate the polarization state of the first color light.
The optical device according to any one of claims 1 to 3, wherein the optical device is a second color-selective polarizer configured to rotate the polarization state of the first color of light from the second polarization state to the first polarization state without rotating the polarization state of the second color of light, and the first optical diffraction component further comprises a second color-selective polarizer located between the second color-selective polarizer and the color-selective polarizer. The first optical diffraction component comprises a first diffraction structure, and the second optical diffraction component comprises a second diffraction structure.
The optical device comprises a first reflective layer and a second reflective layer, wherein the first reflective layer is located between the first diffraction structure and the second diffraction structure, and the second diffraction structure is located between the first reflective layer and the second reflective layer.
The first diffraction structure is configured to: i) diffract primary and zero-order light of the first color incident at a first incidence angle, wherein the primary light is diffracted at the first diffraction angle and the zero-order light is transmitted at the first incidence angle; and ii) transmit second color light incident at a second incidence angle to the first diffraction structure.
The first reflective layer is configured to: i) completely reflect light of the first color incident on the first reflective layer at the first angle of incidence, and ii) transmit light of the second color incident on the first reflective layer at the second angle of incidence.
The optical device according to any one of claims 1 to 3, wherein the second diffraction structure is configured to diffract primary and zero-order light of the second color incident at a second incidence angle, the primary light is diffracted at a second diffraction angle, the zero-order light is transmitted at a second incidence angle, and the second reflective layer is configured to completely reflect the light of the second color incident at a second incidence angle. It is a system,
An irradiator configured to provide light of multiple different colors,
The optical device includes the one described in any one of claims 1 to 15 ,
A system in which the optical device is positioned adjacent to the irradiator and is configured to receive the plurality of different colored lights from the irradiator and to diffract the plurality of different colored lights. The system according to claim 16, wherein the optical device is configured to diffract the plurality of different colored lights at their respective diffraction angles, each of which is in the range of -10 degrees to 10 degrees. The system according to claim 16 or 17 , further comprising a controller coupled to the irradiator and configured to control the irradiator to provide each of the plurality of different colored lights. The system further includes a display comprising a plurality of display elements, the optical device is configured to diffract the plurality of colored lights toward the display, and/or
The controller is coupled to the display and is configured to transmit respective control signals to each of the plurality of display elements for modulation of at least one characteristic of the display elements, and/or
The controller acquires graphic data including primitive data for each of the multiple primitives corresponding to an object in three-dimensional space, determines the electromagnetic (EM) field contribution of the display to each of the multiple display elements for each of the multiple primitives, and for each of the multiple display elements
The system according to claim 18, configured to generate the sum of the EM field contributions to the display element from the plurality of primitives, and for each of the plurality of display elements, generate the respective control signals based on the sum of the EM field contributions to the display element. It is a system,
A display with multiple display elements,
The optical device includes the one described in any one of claims 1 to 15 ,
A system in which the optical device is configured to diffract light of multiple different colors toward the display. The system according to claim 20, wherein the optical device and the display are arranged along a certain direction, the optical device has a front and a back along the direction, the display has a front and a back along the direction, and the front of the display is spaced apart from the back of the optical device . The front surface of the display is separated from the back surface of the optical device by a gap, and/or
At least one of the front surface of the display or the back surface of the optical device is treated with an anti-reflective coating and/or
The system further includes a transparent protective layer on the back surface of the optical device and/or
The front of the display and the back of the optical device are attached together by an intermediate layer, and/or
The intermediate layer is configured to have a refractive index lower than that of the layer of the optical device, such that each of the plurality of colors of light transmitted in zero order by the optical device is completely reflected at the interface between the intermediate layer and the layer of the optical device, and/or
The system further includes a cover on the front surface of the display, the optical device is formed within the cover glass, and/or
The optical device is configured to receive the plurality of colors of light on the front surface of the optical device, and/or
The optical device is configured to diffract the plurality of different colored lights at their respective diffraction angles, and/or
Each of the aforementioned diffraction angles is in the range of -10 degrees to 10 degrees, and/or
The display is configured to diffract the diffracted color light backward through the optical device, and/or
A region of the optical device covers a region of the display and/or
The display comprises a spatial light modulator (SLM) including a digital micromirror device (DMD) or a liquid crystal on silicon (LCOS) device, and/or
The system according to claim 21, further comprising an optical polarizer disposed between the display and the optical device, wherein the optical polarizer is configured to change the polarization state of the plurality of different colored lights. The system according to claim 21 or 22 , wherein the optical device comprises a substrate in front of the optical device and is configured to receive the plurality of colored lights from at least one side of the substrate. The optical device is configured to have a substrate in front of it and to receive the plurality of colors of light from at least one side of the substrate, and/or
The optical device comprises at least one diffraction grating supported by the substrate and configured to diffract the plurality of different colored lights toward the display, and/or
The substrate comprises a container filled with a liquid having a refractive index smaller than that of the recording medium of the diffraction grating, and/or
The substrate is wedge-shaped and has an inclined front surface, and/or
The angle between the front surface and the side surface is less than 90 degrees, and/or
The optical device is configured to receive different portions of the multiple different colored lights along different optical paths within the substrate, and to diffract the different portions to illuminate different corresponding areas of the display, and/or
The aforementioned different regions comprise two or more of the lower region, upper region, left region, and right region of the display, and/or
The aforementioned different portions of light of multiple different colors are provided by different corresponding irradiators and/or,
The optical device is configured to receive different portions of the plurality of different colored lights from different corresponding sides of the substrate, and/or
The optical device is configured to receive a first portion of the plurality of different colored lights from a first side surface of the substrate to the back surface of the optical device, diffract the first portion to illuminate a first area of the display, and/or to receive a second portion of the plurality of different colored lights from a second side surface of the substrate to the front surface of the optical device, reflect the second portion backward against the back surface of the optical device, diffract the second portion to illuminate a second area of the display, and/or
The first side and the second side are the same side, and/or
The second portion of the plurality of different colored lights is reflected by total internal reflection or a reflection grating within the optical device, and/or
The system according to claim 23, wherein the substrate comprises a partially reflective surface configured to separate the input light into a first portion and a second portion. The system according to claim 21 or 22 , wherein the optical device comprises at least one diffraction grating disposed on the back surface of the optical device. The diffraction grating comprises different sub-regions having different corresponding diffraction efficiencies, and/or
The diffraction grating is configured to diffract a first portion of the plurality of different colored light incident on a first sub-region of the diffraction grating to illuminate a first region of the display, and further to reflect a second portion of the plurality of different colored light, which is reflected backward from the back surface of the optical device and incident on a second sub-region of the diffraction grating, back to the front surface of the optical device, and to diffract the second portion to illuminate a second different region of the display, and/or
The diffraction grating is configured such that the diffracted first portion and the diffracted second portion on the first and second regions of the display have the same optical power, and/or
The system according to claim 25, wherein the first region and the second region of the display have different reflectances associated with a first different diffraction efficiency and a second different diffraction efficiency of the first sub-region and the second sub-region of the diffraction grating. The system according to claim 25 or 26 , wherein the diffraction grating comprises a plurality of sub-regions tiled together. The diffraction grating comprises a plurality of sub-regions tiled together, and/or
The aforementioned sub-region is tiled along the horizontal direction and/or
The edges of the different sub-regions are configured to contact each other in an optically seamless manner, and/or
The distinct sub-regions are formed by including one or more edge-defining elements in at least one optical path of the recording beam or object beam when recording each sub-region on the recording medium, and the one or more edge-defining elements comprises a square aperture, a rectangular aperture, or a planar tile aperture, and/or
Two adjacent sub-regions of the diffraction grating are in contact with the gap, and/or
The display comprises a plurality of tile-like display devices, and the gap between adjacent sub-regions of the diffraction grating is aligned with the gap between adjacent tile-like display devices of the display, and/or
Two adjacent and distinct subregions have an overlap, and/or
The diffraction grating is mechanically formed by using an embossed structure, a nanoimprinted structure, or a self-assembled structure, and/or
The system according to claim 27, wherein the display has a width along the horizontal direction and a height along the vertical direction, both the horizontal and vertical directions being perpendicular to the direction, and the aspect ratio of the width to the height is greater than 16:9. The system according to any one of claims 24 to 28 , further comprising an irradiator positioned adjacent to the optical device and configured to provide the optical device with light of the plurality of colors. The irradiator comprises a plurality of light-emitting elements, each configured to emit light of a different color, and/or
The centers of the beams from the plurality of light-emitting elements are offset from each other, and/or
The irradiator is configured to provide a light beam having an elliptical beam profile or a rectangular beam profile, and/or
The irradiator is configured to provide a light beam with a specific polarization orientation, and/or
The irradiator comprises one or more optical components configured to independently control the ellipticity and polarization orientation of each of the plurality of different colored lights, and/or
The irradiator comprises one or more optical components configured to control the uniformity of the plurality of different colored lights, and/or
The one or more optical components include an apodizing optical element or a profile converter, and/or
The system according to claim 29, wherein the system includes one or more anamorphic optical elements or one or more cylindrical optical elements configured to increase the width of the plurality of different colored lights. A prism element between the irradiator and the optical device, configured to receive the plurality of different colored lights from the input surface of the prism element,
The system according to claim 29 or 30, comprising one or more expansion gratings adjacent to the exit surface of the prism element, each of which is configured to expand the beam profiles of light of different corresponding colors by a coefficient of at least one dimension. The system further includes one or more reflectors located downstream of the one or more expansion diffraction gratings, each of which reflects light of a particular color back to the optical device.
It is configured to fire, and/or,
The tilt angle of each of the one or more reflectors is independently adjustable to cause uniformity of diffraction from the optical device to the display, and/or
The system further includes at least one of a color sensor or a luminance sensor configured to detect one or more optical properties of the holographic light field formed by the system, wherein the tilt angle of the one or more reflectors is adjustable based on the detected optical properties of the holographic light field, and/or
The one or more optical properties include brightness uniformity, color uniformity, or a white point, and/or
The one or more reflectors are adjustable to compensate for changes in the alignment of the components of the system, and/or
The optical distance between the one or more reflectors and the optical device is configured such that each of the multiple different colored lights is reflected by the corresponding reflector without transmission through one or more other reflectors, and/or
The one or more reflectors are configured such that the light emitted from each of the one or more reflectors comes from different directions, and/or
The angle between the prism element and the substrate of the optical device is adjustable so as to tilt the position of the holographic light field formed by the system, and/or
The system according to claim 31, wherein one or more extended gratings are configured to collimate the plurality of different colored lights in one or two transverse directions, at least partially. The system according to any one of claims 29 to 32 , further comprising a controller coupled to the irradiator and configured to control the irradiator to provide each of the plurality of colors of light. The controller is coupled to the display and is configured to transmit respective control signals to each of the plurality of display elements for modulation of at least one characteristic of the display elements, and/or
The controller is configured to acquire graphic data including primitive data for each of a plurality of primitives corresponding to an object in three-dimensional space, determine the electromagnetic (EM) field contribution of each of the plurality of primitives to each of the plurality of display elements of the display, generate the sum of the EM field contributions from the plurality of primitives to each of the plurality of display elements, and/or generate the respective control signals for each of the plurality of display elements based on the sum of the EM field contributions to the display element, and/or
The controller is configured to sequentially modulate the display with information associated with the plurality of colors of light over a series of periods, and to control the irradiator to sequentially emit each of the plurality of colors of light to the optical device during each period of the series of periods, such that each of the plurality of colors of light is diffracted toward the display by the optical device and reflected by the modulated display elements of the display to form a three-dimensional light field of each color corresponding to the object within each period, and/or
The system according to claim 33, wherein the controller is configured to modulate the display such that each of the three-dimensional color light fields appears i) entirely in front of the display, ii) entirely behind the display, or iii) partially in front of the display and partially behind the display. The system according to any one of claims 20 to 34, wherein the optical device comprises an optical diffraction component configured to diffract light containing a plurality of different colors toward a display configured to diffract a portion of the light illuminating the display element. The optical device further comprises an optical redirection component configured to transmit a portion of the light to form a holographic scene and to redirect the zero-order display light away from the holographic scene in three-dimensional (3D) space, wherein the zero-order display light includes reflected light from the display and/or
The optical redirection component comprises a plurality of redirection holographic gratings for the display zero-order light of the plurality of different colored lights, and each of the plurality of redirection holographic gratings is configured to diffract the display zero-order light of each of the plurality of different colored lights in the 3D space in the respective direction and at the respective diffraction angle, and/or
The optical diffraction component is configured to diffract the plurality of different colored lights so as to redirect the zero-order light of the display reflected from the display away from the holographic scene, thereby illuminating the display at a 0° angle, and/or
The ratio of the amount of display zero-order light in the holographic scene with the suppression of the optical diffraction component and the optical redirection component to the amount of display zero-order light in the holographic scene without the suppression is less than 2%, and/or
The system according to claim 35, wherein the optical redirection component comprises a one-dimensional suppression grating, the holographic scene includes a band corresponding to the suppression of zero-order light of the display, and the system is configured such that the band is outside the viewer's field of view.