JP4014396B2 - Optical path switching element and spatial light modulator using the element - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an optical path switching element, and a spatial light modulator using the element, more specifically, an optical path switching element that is an optical switching device that changes an optical path by changing a reflection direction of incident light, and The present invention relates to a spatial light modulator using an optical path switching element.
[0002]
[Prior art]
As a device for switching light by changing the reflection direction of incident light and a spatial light modulator using the device, for example, a large number of minute rotating mirrors as disclosed in Japanese Patent Laid-Open No. 5-196880 are arrayed two-dimensionally. Is known.
[0003]
FIG. 22 is a plan view of the spatial light modulator described in the above-mentioned Japanese Patent Laid-Open No. 5-196880. On the plane, only the rectangular torsion beam reflecting surface 71 and the beam support post 72 are observed as shown in FIG. Is done. 23 is a cross-sectional view of one rotating mirror of the spatial light modulator shown in FIG. 22, FIG. 23 (A) is a cross-sectional view along the hinge, and FIG. 23 (B) is a cross-sectional view in a direction perpendicular thereto. is there. The beam support post 72 enables the beam 71 to rotate toward the ground electrode 74 by twisting of a hinge 73 connected to the post 75. The driving force is given by a voltage applied to the address electrode 77 supported by the post 76. A voltage is applied to the address electrode 77 by transmitting a signal of a CMOS circuit (not shown) provided on the substrate layer 79 through the metal layer 78. By changing the rotation state of the beam 71 for each rotary mirror, the incident light can be spatially modulated two-dimensionally.
In the above system, the structure of the rotary mirror is complicated in order to obtain a large rotation angle, and there is a problem that the manufacturing cost increases.
[0004]
As another optical switching element, for example, there is an optical switching element disclosed in JP-A-11-202222. FIG. 24 is a diagram for explaining the operation of the optical switching element proposed in Japanese Patent Laid-Open No. 11-202222. This optical switching element captures evanescent light by reflecting the light guide member 81 having a total reflection surface 82 capable of transmitting the light by totally reflecting the light, and the extraction surface 92 close to the total reflection surface 82. And a driving unit 100 that drives the prism 91 to approach or move away from the light guide member 81 in this order in the light emission direction. Yes. The cell on the right side of FIG. 24 shows a state in which the prism 91 is located more than the extraction distance at which evanescent light leaks by operating the driving unit 100. At this time, the light beam 101 propagating through the light guide member 81 is totally reflected by the total reflection surface 82 and is emitted in the right direction in the figure as shown in FIG. When the driving unit 100 is not operated, the prism 91 is close to the extraction distance or less where the evanescent light leaks as shown in the left cell of FIG. As shown in the left cell of 24, the light enters the prism 91 without being reflected by the total reflection surface 82. The light beam that has entered the prism 91 is reflected by the reflecting surface 91a of the prism, and is transmitted through the light guide member 81 and emitted as the light beam 103 shown in FIG.
[0005]
In the above system, a relatively simple drive mechanism can be employed to switch between the two states of extraction and non-extraction of evanescent light, since a minute displacement less than or equal to the wavelength of light may be used. Since the prism 91 as shown in FIG. 3 is complicated in structure, it is difficult to uniformly form a plurality of prisms 91 on a substrate with a minute size, resulting in a decrease in manufacturing yield and an increase in cost. There's a problem. Further, when the prism 91 is brought close to the light guide member 81 and the total reflection surface 82, there is also a problem that the van der Waals force or the liquid bridging force acts to make it difficult to peel off.
[0006]
Furthermore, as another optical switching element, there is an optical switching element disclosed in Japanese Patent Laid-Open No. 2000-171813. FIG. 25 is a diagram showing a schematic configuration of an optical switching element proposed in Japanese Patent Laid-Open No. 2000-171813. The orientation of the liquid crystal molecules is controlled by applying a voltage to the liquid crystal 120 that is brought into contact with the light guide 110 that transmits light by total reflection, whereby the effective refractive index is set to a value for extraordinary light and a value for ordinary light. Vary between. As a result, it is possible to switch between a state in which incident light (linearly polarized light) 112 is emitted as total reflected light 113 and a state in which the incident light (linearly polarized light) 112 is changed in direction by the reflective film 121 and then emitted as reflected light 114 after becoming transmitted light. it can. In FIG. 25, 111 is a transparent electrode, 130 is a liquid crystal driving IC substrate, and 131 is an electrode terminal.
[0007]
In this method, since there is no mechanical drive unit, the above-mentioned problems do not occur, but the light guide is made of a material having a high refractive index in order to totally reflect it at the interface between the light guide and the liquid crystal. There are restrictions that need to be produced or that the incident angle of light has to be increased, which raises material costs, complicates the optical system, and lowers the light utilization efficiency. May occur.
In order to solve the above problems, the present inventors have proposed an optical path switching element shown in FIG. 26, a spatial light modulator using the same, and an image display device in Japanese Patent Application No. 2001-187577.
[0008]
The optical path switching element proposed in Japanese Patent Application No. 2001-187777 is refracted between the light incident part 3 via the light guide member 1 and the light reflecting part 6 that reflects incident light entering from the light incident part 3. The optical switching is performed by enclosing the refractive index variable material 5, changing the refractive index of the refractive index variable material 5 by applying a signal, and switching between the total reflection state and the non-total reflection state in the light emitting unit 4.
In general, since the refractive index varies depending on the wavelength of incident light, the type of material, temperature, and the like, there is a problem that the refraction angle varies depending on the wavelength and temperature. For this reason, there is a problem that the light transmission efficiency is lowered due to the optical path deviation, the pixel deviation or the color deviation occurs, and sufficient performance cannot be obtained as the optical path switching element, the spatial light modulator, and the display device.
[0009]
[Problems to be solved by the invention]
SUMMARY OF THE INVENTION An object of the present invention is to solve the above problems and to provide an optical path switching element having a large S / N ratio that prevents optical path and pixel shift or color shift and a spatial light modulator using the optical path switching element. . More specifically,
(1) To provide an optical path switching element with a simple structure, high durability, reduced member cost, high light utilization efficiency, and high S / N ratio that does not cause optical path shift depending on the wavelength of incident light. 1),
(2) To provide an optical path switching element capable of preventing an optical path shift without requiring a complicated control mechanism (claim 2),
(3) To provide an optical path switching element capable of preventing optical path deviation without requiring a complicated control mechanism (claim 3);
(4) to provide an optical path switching element capable of increasing the S / N ratio (claim 4);
(5) To provide an optical path switching element capable of further increasing the S / N ratio (claim 5),
[0010]
(6) to provide an optical path switching element capable of increasing the S / N ratio (Claim 6);
(7) In addition to the above, providing an optical path switching element that is easy to manufacture (claim 7),
(8) In addition to the above, to provide an optical path switching element capable of reducing drive energy (claim 8),
(9) Furthermore, providing an optical path switching element capable of reducing drive energy (claim 9),
(10) Further, an optical path switching element that is easy to manufacture and that can increase the S / N ratio is provided (claim 10).
[0011]
(11) In addition to the above, providing an optical path switching element with a high response speed (claim 11),
(12) In addition to the above, providing an optical path switching element with small optical loss (claim 12),
(13) In addition to the above, further provides an optical path switching element capable of increasing the S / N ratio (claim 13),
(14) To provide a spatial light modulator having a simple structure, high durability, reduced member cost, high light utilization efficiency, and high S / N ratio (claim 14);
Is the purpose.
[0012]
  According to a first aspect of the present invention, there is provided a light incident portion that causes light incident through the light guide member to be incident on the refractive index variable material, and a reflective portion that reflects incident light that has entered the refractive index variable material from the light incident portion. A light emitting part that emits light as outgoing light through the light guide member, encapsulating the refractive index variable substance in an optical path including the reflecting part, and sending a signal according to information to the refractive index variable substance In an optical path switching element having a signal input means for causing a change in refractive index, a change in refractive index of the refractive index variable substance due to the signal is caused by the incident light at an interface between the light guide member and the refractive index variable substance. Provided means for controlling the direction of the outgoing light in accordance with the wavelength of the incident light so that the optical path of the outgoing light does not deviate depending on the wavelength of the incident light.The means for controlling the direction of the emitted light according to the wavelength of the incident light is an incident light adjusting mechanism that adjusts the incident angle and the incident position of the incident light to the light guide member according to the wavelength of the incident light.It is characterized by that.
[0014]
  Claim2The invention ofA light incident part for allowing light incident through the light guide member to enter the refractive index variable substance, a reflection part for reflecting incident light that has entered the refractive index variable substance from the light incident part, and the light guide member. And a light emitting part that emits the light as an outgoing light. The refractive index variable substance is enclosed in an optical path including the reflecting part, and a signal is given to the refractive index variable substance according to information to cause a refractive index change. In the optical path switching element comprising a signal input means, the refractive index change of the refractive index variable substance due to the signal is performed in a range in which the incident light is not totally reflected at the interface between the light guide member and the refractive index variable substance, And a means for controlling the direction of the outgoing light according to the wavelength of the incident light is provided so that the optical path of the outgoing light does not shift depending on the wavelength of the incident light,The means for controlling the direction of the emitted light according to the wavelength of the incident light is a bias applying mechanism that applies a bias signal to the refractive index variable substance according to the wavelength of the incident light.
[0015]
  Claim3The invention of claim 1Or 2In the first aspect of the present invention, the light reflected by the reflecting part is totally reflected at the interface between the light guide member and the external substance in contact with the light reflecting part by the change in the refractive index of the refractive index variable substance due to the signal. And a second state in which total reflection is not possible.
[0016]
  Claim4The invention of claim 1 to claim 13In the invention according to any one of the above, the light incident portion and the light emitting portion are configured by surfaces that are not parallel to each other.
[0017]
  Claim5The invention of claim 1 to claim 14The invention according to any one of the above, is characterized in that a second light emitting portion is provided that can emit the emitted light to the outside via the second light guide member.
[0018]
  Claim6The invention of claim 1 to claim 15In the invention according to any one of the above, a flat light guide body that is optically joined to the light incident portion and has a refractive index substantially equal to that of the light guide member is provided.
[0019]
  Claim7The invention of claim 1 to claim 16In the invention according to any one of the above, an angle formed by incident light that has entered the refractive index variable material and a normal of the surface that constitutes the light incident portion, the reflective portion being configured by two surfaces sharing one side The maximum value in the operating range of_2maxThen, the angle formed by the normal line of at least one surface constituting the reflection part and the normal line of the surface constituting the light incident part is 90 ° −θ._2maxIt is characterized by the following.
[0020]
  Claim8The invention of claim 1 to claim 17In the invention according to any one of the above, the reflecting portion has a plurality of sets of surfaces with respect to a unit element that applies a signal to the refractive index variable substance.
[0021]
  Claim9The invention of claim 1 to claim 18In the invention according to any one of the above, the refractive index variable substance is made of liquid crystal.
[0022]
  Claim10The invention of claim 1 to claim 18In the invention according to any one of the above, the refractive index variable substance is made of a liquid crystal / polymer composite in which a liquid crystal material is dispersed and held in a polymer matrix.
[0023]
  Claim11The invention of claim10In the invention, the liquid crystal material is a droplet having a particle size of 1/5 or less of the wavelength of incident light.
[0024]
  Claim12The invention of claim9 to 11In the invention according to any one of the above, all liquid crystal molecules are arranged in approximately one direction when no voltage is applied.
[0025]
  Claim13The invention of claim 1 to claim 112The optical path switching elements according to any one of the above are arranged in a one-dimensional array or a two-dimensional array.
[0026]
DETAILED DESCRIPTION OF THE INVENTION
(Configuration / Operation)
A feature of the present invention is that a light incident portion via a light guide member, a reflection portion that reflects incident light that has entered from the light incident portion, and light reflected by the reflection portion is emitted through the light guide member. And a signal input means for enclosing a refractive index variable substance in an optical path including the reflection part and providing a signal according to information to the refractive index variable substance to cause a refractive index change. And an optical path switching element that changes the refractive index of the refractive index variable material by the signal in a range in which the incident light is not totally reflected at the interface between the light guide member and the refractive index variable material. According to the present invention, there is provided an optical path switching element characterized in that means for controlling the direction of outgoing light is provided.
[0027]
Here, the refractive index of the light guide member is n₁, The refractive index of the refractive index variable substance is n₂And the angle (incident angle) between the light transmitted through the light guide member and the normal of the surface constituting the light incident part is θ₁When the incident light enters the refractive index variable material, the angle (refractive angle) formed with the normal of the surface constituting the light incident part is θ₂Then, the following equation holds according to Snell's law.
sinθ₂/ Sinθ₁= N₁/ N₂... (1)
[0028]
N by external signal₂Changes to θ according to equation (1)₂As a result, the reflection angle at the reflecting portion changes, and the incident angle to the light emitting portion changes. The angle change is approximately θ₂The refractive index n of the light guide member₁Is the refractive index n of the external material in contact with the light guide member_a(Usually the external material is air and n_a= 1) If larger, refraction occurs when the light exits from the light exit, and the amount of change in the angle (exit angle) between the exit light and the normal of the surface constituting the light exit is θ₂It becomes larger than the amount of change. Thus, if the light output is detected at a predetermined position, n₂With this change, the optical output changes, and optical switching by applying a signal becomes possible. In the optical path switching element of the present invention, in principle, the refractive index n of the light guide member₁And incident angle θ₁Therefore, a device and a system using inexpensive members can be realized.
[0029]
At this time, since the means for controlling the direction of the emitted light according to the wavelength of the incident light is provided, the deviation of the optical path can be prevented even if the wavelength of the incident light changes. As a result, it is possible to provide an optical path switching element with a simple structure, high durability, reduced member cost, high light utilization efficiency, and high S / N ratio that does not cause an optical path shift depending on the wavelength of incident light ( Claim 1).
Further, the means for controlling the direction of the emitted light according to the wavelength of the incident light is an incident light adjusting mechanism for adjusting the incident angle and the incident position of the incident light to the light guide member according to the wavelength of the incident light. It is said. Accordingly, it is possible to provide an optical path switching element that can prevent an optical path shift without requiring a complicated control mechanism (claim 2).
[0030]
Further, the means for controlling the direction of the emitted light according to the wavelength of the incident light is a bias applying mechanism that applies a bias signal to the refractive index variable material according to the wavelength of the incident light. Thus, it is possible to provide an optical path switching element that can prevent an optical path shift without requiring a complicated control mechanism. Since the refractive index of the refractive index variable substance depends on the wavelength of the incident light, and the amount of change in the refractive index varies depending on the material, the refractive index of the light guide member and the refractive index variable substance changes in the same way for light of a certain wavelength. Not always. Therefore, even if light is incident at a constant incident angle, the refraction angle changes depending on the wavelength, and as a result, the emission direction changes depending on the wavelength. Therefore, in the present invention, as shown in FIG. 4, in addition to the drive signal generator 22 that applies a signal to the metal film 7 according to an external signal, a bias for applying a constant bias signal according to the wavelength of incident light. A signal generator 23 is provided to control the refractive index of the refractive index variable substance by superimposing a bias signal in accordance with the wavelength of the incident light source, so that the angle of the emitted light becomes constant. Thus, by changing the bias signal to be applied, the direction of the outgoing light can be kept constant for incident light of any wavelength.
[0031]
In addition, the refractive index change of the refractive index variable substance due to the signal is not totally reflected in the first state where the light reflected by the reflecting part is totally reflected at the interface between the light guide member and the external substance in contact with the light emitting part. It is preferable to carry out within a range that can be taken with the second state. In this case, θ₂The amount of change in the emission angle becomes very large compared to the amount of change in (3), and a higher S / N ratio can be obtained.
[0032]
In the above, it is preferable that the light incidence part and the light emission part are configured by surfaces that are not parallel to each other. By doing so, the amount of change in the emission angle can be increased, so that a higher S / N ratio can be obtained.
It is preferable to provide a second light emitting portion that can emit the emitted light to the outside via the second light guide member. Since the light emitted from the light emitting part again enters the second light guide member and is emitted from the second light emitting part, an optical path switching element having a high S / N ratio can be provided.
[0033]
Further, in the above, it is preferable from the viewpoint of ease of manufacture to provide a flat light guide optically joined to the light incident portion and having a refractive index substantially equal to that of the light guide member. In this case, it is only necessary to optically contact the light guide member after manufacturing a device composed of the flat plate light guide, the reflective member, and the refractive index variable material sandwiched therebetween, Manufacture is much easier than manufacturing a device using a light guide member.
[0034]
The reflection part is composed of two surfaces sharing one side, and the maximum value in the operating range of the angle between the incident light that has entered the refractive index variable material from the light incident part and the normal of the surface that constitutes the light incident part is θ_2maxThen, the angle formed by the normal of at least one surface constituting the reflecting portion and the normal of the surface constituting the light incident portion is 90 ° −θ._2maxThe following is preferable. By doing so, the distance from the reflecting portion to the light incident portion can be reduced, so that the energy (driving energy) given to the refractive index variable substance can be reduced.
[0035]
Furthermore, it is preferable that the reflecting portion has a plurality of sets of surfaces for the unit element that applies a signal to the refractive index variable substance. By doing so, the distance from the reflecting portion to the light incident portion can be further reduced, so that the driving energy can be further reduced.
[0036]
As the refractive index variable substance, any substance can be used as long as the refractive index is changed by applying energy from the outside, but a so-called electro-optical material in which the refractive index is changed by an electric field is preferable for ease of control. Can be used. As an electro-optic material, LiNbO exhibiting the Pockels effect_ThreeBaTiO which shows the car effect_ThreeAmong them, solid crystals such as PLZT and liquid crystals are known. Among them, liquid crystals are preferable because of a large amount of change in refractive index per electric field strength and fluidity. Since the amount of change in refractive index is large, θ₂Can be increased, and as a result, the angle φ incident on the light emitting portion₁Since the amount of change of can be increased, the state of total reflection and the state of not total reflection can be switched reliably, so that a high S / N ratio can be obtained. Further, due to the fluidity, optical contact with the light guide member (or the flat light guide) and the reflection member can be easily realized (claim 10).
[0037]
A liquid crystal / polymer composite is preferably used as the refractive index variable substance from the viewpoint of response speed. As such a liquid crystal / polymer composite, a so-called polymer dispersed liquid crystal in which liquid crystal droplets are dispersed in a polymer matrix can be suitably used. It has been experimentally found that the response speed of polymer-dispersed liquid crystals increases as the particle size of the liquid crystal droplets decreases, and in particular, the scattering can be reduced by setting the particle size to 1/5 or less of the wavelength of incident light. This is preferable because the light transmittance is decreased and the light transmittance is increased, that is, the light loss is remarkably reduced. The particle size referred to here is a particle size representative of a structure, and usually an average particle size measured by an electron micrograph or the like is suitably used (claims 11 and 12).
[0038]
In the above liquid crystal, it is preferable that all liquid crystal molecules are arranged in approximately one direction when no voltage is applied. Since a large refractive index difference can be obtained by making this direction substantially orthogonal to the direction in which liquid crystal molecules are aligned when a voltage is applied (electric field direction), θ₂Can be increased, and as a result, the angle φ incident on the light emitting portion₁Therefore, it is possible to reliably switch between the state of total reflection and the state of not total reflection, thereby obtaining a high S / N ratio.
[0039]
A spatial light modulator can be configured by arranging the optical path switching elements according to the present invention one-dimensionally or two-dimensionally. Such a spatial light modulator is simple in structure and has few restrictions on members to be used, so that it is highly durable and inexpensive. A spatial light modulator arranged in one dimension can perform two-dimensional spatial light modulation by using a scanning mechanism that scans in a direction perpendicular to the arrangement direction of the optical path switching elements, but a one-dimensional spatial light modulator is a two-dimensional spatial light modulator. Since it is cheaper than the spatial light modulator, the cost is lower. That is, it is possible to provide a spatial light modulator that is simple in structure, high in durability, can reduce member costs, and has high light utilization efficiency.
[0040]
In addition, by providing the spatial light modulator, a light beam incident means, and a means for enlarging and projecting an image formed by the spatial light modulator on the screen, a highly durable and inexpensive image display apparatus can be configured.
[0041]
(Embodiment 1)
FIG. 1 is a diagram for explaining a first embodiment of the present invention, in which 1 is an optically transparent light guide member made of glass, plastic or the like, and the light guide member 1 is from a light source. A light incident part 3 for making the light beam incident on the refractive index variable substance 5, and a light emitting part 4 for emitting the light ray reflected by the reflecting part 6 to the outside of the light guide member 1. In this example, the surface constituting the light incident part 3 and the surface constituting the light emitting part 4 are parallel. The reflecting member 15 including the reflecting portion 6 is formed on a substrate 9 made of Si, glass or the like by forming an inclined surface with an insulator 8 made of ceramic such as glass, plastic, silicon oxide, silicon nitride, or aluminum oxide. Further, a highly reflective metal film 7 made of Al, Ag or the like can be formed by a known method such as vacuum deposition or sputtering. Further, if necessary, patterning may be performed by photolithography etching. This metal film 7 also functions as an electrode. It is desirable to form a driving element or the like for applying a signal voltage to the metal film 7 on the substrate 9.
[0042]
The reflecting member 15 may have a configuration in which the insulator 8 also serves as the substrate 9 or a configuration in which an inclined surface is directly formed using a metal plate as a substrate. As an example of a suitable inclined surface forming method, there is an anisotropic etching method in which dry etching is performed by patterning using a photomask in which a pattern of area gradation or density gradation is formed. As the refractive index variable material 5, liquid crystal can be preferably used. As the liquid crystal material, nematic liquid crystal, smectic liquid crystal, cholesteric liquid crystal, or the like can be used, and a single or two or more kinds of liquid crystal compounds or a mixture containing substances other than liquid crystal compounds may be used.
[0043]
The light incident part 3 is provided with a transparent electrode 10 made of ITO or the like for applying a voltage to the refractive index variable substance 5. When the refractive index variable substance 5 is made of a fluid material such as liquid crystal, a sealing material 11 made of an epoxy resin or the like is preferably formed and held. If an example of a manufacturing process is shown, after printing the thermosetting epoxy resin in the peripheral part of the light guide member 1 (or the reflection member 15) leaving a part of the opening (injection hole), the reflection member 15 (or The light guide member 1) is bonded and heat cured. After the liquid crystal is injected from the injection hole, the hole is closed with an adhesive to complete.
[0044]
FIG. 1A shows the refractive index n of the refractive index variable material 5.₂Is the refractive index n of the light guide member 1₁If larger, refraction angle θ₂Is the incident angle θ according to equation (1)₁Smaller. The angle formed between the normal of the surface constituting the reflecting portion 6 and the normal of the surface constituting the light incident portion 3 = the inclination angle α of the surface constituting the reflecting portion is α = θ₂If set to / 2, the reflected light enters the light incident portion 3 perpendicularly and exits.
[0045]
FIG. 1 (B) shows n₂Is n₁Is roughly the same as₂Is θ₁Therefore, the reflection angle becomes larger than that in FIG. 1A, and the reflected light is approximately φ with respect to the light emitting portion 4.₁= Θ₁−θ₂The external substance 2 that is incident at an angle of and is in contact with the light guide member 1 is air (n_a= 1) In case of emission angle φ₂= Sin^-1(N₁sinφ₁). When the photodetector 13 is installed so that the emitted light in FIG. 1A is incident perpendicularly to the detection surface, the detection (ON state) in the case of FIG. 1A is detected in FIG. 1B. In some cases, it is hardly detected (OFF state), and a good S / N ratio is obtained.
Here, when the wavelength of the incident light changes, the incident angle and the incident position of the incident light to the light guide member 1 are incident so that the position and direction of the emitted light from the light emitting unit 4 are the same regardless of the wavelength. An incident light adjustment mechanism that adjusts according to the wavelength of light is used.
[0046]
The refractive index of the refractive index variable material 5 depends on the wavelength of the incident light, and the refractive index change amount differs depending on the material. Therefore, the refractive index of the light guide member 1 and the refractive index variable material 5 is the same for light of a certain wavelength. It does not always change. Therefore, as shown in FIG. 2, when light of different wavelengths is incident at the same incident angle, the refraction angle changes depending on the wavelength, and as a result, λ₁, Λ₂, Λ_ThreeAs shown, the emission direction changes depending on the wavelength. Therefore, the incident light incident on the light guide member 1 according to the wavelength of the incident light so that the reflected light enters the photodetector 13 regardless of the wavelength of the incident light as shown in FIG. The incident position and angle of incidence are changed. Thereby, it is possible to prevent the optical path shift of the emitted light due to the wavelength. Also in the off state, the position and angle of the incident light may be adjusted so that the outgoing light does not cause an optical path shift depending on the wavelength, or the off-state outgoing light that has caused the optical path shift as shown in FIG. If the light does not enter the detector 13, it is not necessary to adjust the position and angle of the incident light in the off state. However, when used as a spatial light modulator or display device as will be described later, both the on-state and off-state are output by a single incident light, so the incident light position and angle are prevented so as to prevent the optical path deviation in the on-state. And the optical path deviation is not adjusted in the off state.
[0047]
The incident light adjusting mechanism for adjusting the position and angle of incident light can be realized by changing the position and angle for each light source when providing a light source for each wavelength. When the wavelength is switched by using a filter or the like with one light source, a reflection element 31 such as a mirror or a prism whose reflection angle and position can be varied between the light source 33 and the optical path switching element 30 as shown in FIG. This can be realized.
[0048]
As a specific example, the light guide member 1 is made of crown glass BK7 (nd = 1.517), and the refractive index variable material 5 is nematic liquid crystal E7 (normal light refractive index no = 1.522, extraordinary light refractive index ne = 1.746), the liquid crystal molecules 12 are aligned in advance in a direction that is horizontal to the light incident portion 3 and perpendicular to the paper surface, as shown in FIG. As the alignment film, a known material such as SiO or polyimide can be used, and it is preferably formed at least on the surface of the transparent electrode 10 and the metal film 7. An angle ψ formed by the incident light capturing unit 16 and the light incident unit 3 is set to 60 °. Laser light having three wavelengths (633 nm, 532 nm, and 488 nm) was used as the light source, and the incident angle and the incident position on the light guide member 1 could be changed.
[0049]
In the state of FIG. 1A, the laser beam (wavelength 633 nm) is converted to S-polarized light and perpendicular to the incident light capturing unit 16, that is, θ₁= 60 °, the refractive index of the liquid crystal in the refractive index variable material 5 is n for this light.₂= Ne = 1.746, so θ according to equation (1)₂= 49 °. When α = 24.5 ° is set, the reflected light is emitted perpendicularly to the light emitting portion 4 and enters the photodetector 13. The laser beam having a wavelength of 532 nm is incident on the incident light capturing unit 16 at an incident angle of 0.5 °, so that the reflected light is emitted vertically from the light emitting unit 4 and enters the photodetector 13. The laser beam having a wavelength of 488 nm is incident on the incident light capturing unit 16 at an incident angle of 1 °, so that the reflected light is emitted vertically from the light emitting unit 4 and enters the photodetector 13.
[0050]
In the case of FIG. 1 (B), the outgoing optical paths of the three laser beams deviate, but the deviation is slight, and φ₁Is about 11 ° and the output angle φ₂Exits at approximately 17 °.
As described above, it is possible to prevent the optical path shift due to the wavelength and to obtain a high S / N ratio.
In the above description, the incident light is S-polarized light, but may be P-polarized light. In this case, the behavior of light when a voltage is applied and when no voltage is applied is reversed. When P-polarized light is used, the interface reflection loss is reduced, which is more preferable in terms of light utilization efficiency.
[0051]
(Embodiment 2)
A second embodiment of the present invention will be described with reference to FIG. Unlike the first embodiment, this embodiment differs from the first embodiment in that the position and angle of incident light are the same as in the case of the 633 nm laser light in the first embodiment, that is, perpendicular to the incident light capturing unit 16. Keep it as A bias signal generator 23 for applying a bias signal according to the wavelength of incident light is provided in addition to the drive signal generator 22 for driving the refractive index variable material 5 according to an external signal. In addition, since the refractive index variable material 5 in the present embodiment is a liquid crystal, the applied signal is a voltage, and the bias signal is hereinafter referred to as a bias voltage. A bias voltage is not applied when the wavelength of incident light is 633 nm, and a bias of 0.5 V is applied when the wavelength is 532 nm. In the case of 488 nm, a bias voltage of 1 V is applied. This can prevent the optical path shift due to the wavelength.
[0052]
(Embodiment 3)
A third embodiment of the present invention will be described with reference to FIG. In the present embodiment, unlike the first embodiment, the surface constituting the light incident portion 3 and the surface constituting the light emitting portion 4 are not parallel. Other settings are the same as in the first embodiment. An angle β formed by the surface constituting the light emitting portion 4 and the surface constituting the light incident portion 3 is set to β = 40 °. The rest is the same as in the first embodiment.
[0053]
A laser beam having a wavelength of 633 nm is incident on the incident light capturing unit 16 perpendicularly, a laser beam having a wavelength of 532 nm has an incident angle of 0.5 °, and a laser beam having a wavelength of 488 nm has an incident angle of 1 °. The output angle of all is φ₂= 47 °, and the optical path can be prevented from being shifted in the ON state as shown in FIG. In FIG. 5A, the emission angle φ₂Varies depending on the wavelength of the laser beam, but the difference is small and the light is emitted at about 77 °.
In this case, the difference in emission angle between FIG. 5A and FIG. 5B is 30 °, which is larger than that in the first embodiment, so that even when the emission area is large, leaked light can be detected. It is possible to reduce the decrease in the S / N ratio.
[0054]
(Embodiment 4)
A fourth embodiment of the present invention will be described with reference to FIG. Although the basic configuration is the same as that of the third embodiment, the angle β formed by the surface constituting the light emitting portion 4 and the surface constituting the light incident portion 3 is increased to β = 45 °. Laser light with a wavelength of 633 nm is incident on the incident light capturing section 16 at an incident angle of 48 °, laser light with 532 nm is incident at an angle of 47.5 °, and laser light at 488 nm is at an incident angle of 46.5 °. Thus, the emission angles of the emitted light in the on state are all φ2 = 58 °, and the optical path can be prevented from being shifted in the on state as shown in FIG. 6B. In the case of FIG. 6A, the incident angle φ of the reflected light with respect to the light emitting portion 4₁Is different depending on the wavelength, but the difference is small and is about 45 °. At this time, the external substance 2 is air (n_aIn the case of = 1), the following expression (3) is satisfied, so that the reflected light is totally reflected by the light emitting portion 4.
sinφ₁≧ n_a/ N₁  ... (3)
In this case, the difference in emission angle is 180 ° − (45 ° + 58 °) = 77 °, so that almost no leakage light is detected and a high S / N ratio can be obtained.
[0055]
(Embodiment 5)
FIG. 7 is a diagram for explaining a fifth embodiment of the present invention. In FIG. 7, 17 is a second light guide member made of the same material as the light guide member 1, and 18 is a second light emitting unit that can emit emitted light to the outside via the second light guide member. is there. In this example, the light emitting part 4 and the second light guide member 17 (both finished with smoothness of the order of the wavelength of the incident light) are brought into close contact with each other, thereby creating a gap (air layer) of the wavelength of the incident light. I have it. Further, the surface constituting the second light emitting portion 18 is made substantially parallel to the surface constituting the light incident portion 3. Further, the angle β formed by the light incident surface and the light emitting surface is β = 34 °, and the inclination angle α of the surface constituting the reflecting portion 6 is α = 30 °. Other settings are the same as in the fourth embodiment.
[0056]
In the case of FIG. 7B, the light emitted from the light emitting section 4 travels substantially straight (actually translates by a wavelength), and enters the second light guide member 17 again, and the second light emitting section. The light exits vertically from 18 without any deviation of the optical path due to wavelength. In the case of FIG. 7A, the light reflected by the reflecting member 15 is totally reflected at the interface between the light emitting part 4 and the air layer in the gap as in the fourth embodiment. In this case, since the difference in emission angle between FIG. 7A and FIG. 7B exceeds 90 °, leakage light is not detected, and a very high S / N ratio can be obtained.
[0057]
(Embodiment 6)
FIG. 8 is a view for explaining a sixth embodiment of the present invention, in which 19 is a flat light guide having a refractive index substantially equal to that of the light guide member 1, and the light guide member 1 is optical. Joined. Other configurations are the same as those in the fourth embodiment, and the operation principle is also the same. Optical bonding is a state in which the gap between the two members is close enough to be smaller than the wavelength of the light used. Specifically, a fluid object is interposed between the two members. Can be obtained. A fluid object may be solidified after ensuring close contact with both members. More specifically, it is preferable to use a low-volatile liquid or a photocurable adhesive having a refractive index substantially equal to that of the light guide member 1 and the flat light guide 19 as a fluid object. In this embodiment, the flat light guide 19 is in contact with the refractive index variable material 5, so the transparent electrode 10 is formed on the flat light guide 19. In this case, since the light guide member 1 may be joined lastly, the main part of the device can be manufactured without using the light guide member 1 having a complicated shape, so that the yield is improved and the cost is reduced. be able to.
[0058]
(Embodiment 7)
FIG. 9 is a diagram for explaining the seventh embodiment of the present invention. In this case, the reflecting portion 6 is constituted by two surfaces (the reflecting surface 24 and the reverse inclined surface 25) sharing one side, and is refracted. Angle (refraction angle) θ formed between incident light that has entered the rate variable material 5 and a normal line of the surface that constitutes the light incident portion 3₂The maximum value in the operating range of_2maxThen, the angle formed by the normal of at least one surface constituting the reflecting portion 6 (in this example, the reverse inclined surface 25) and the normal of the surface forming the light incident portion 3 = the inclination angle γ of the reverse inclined surface. 90 ° -θ_2maxIt is as follows. Other configurations are the same as those of the third embodiment. In this case, θ_2max= Θ₁= 60 °, and when γ is set to 30 ° or less, the incident area A of the incident light in the light incident portion 3 is the same as that in the first embodiment, so that the light guide member 1 is exposed from the bottom of the reflecting surface 24. The distance to the light incident part 3, that is, the maximum layer thickness t of the refractive index variable material 5_maxThe driving voltage can be lowered.
[0059]
(Embodiment 8)
FIG. 10 is a diagram for explaining an eighth embodiment of the present invention. In this case, a plurality of sets of reflecting surfaces 24 and reverse inclined surfaces 25 are provided in a region facing the irradiation area A in the embodiment of FIG. In FIG. 10, two sets) are provided. As is clear from FIG. 10, when the irradiation area A is equal to FIG._maxCan be further reduced, and the drive voltage can be further reduced.
[0060]
In the present invention, since the refractive index of the light guide member 1 may be equal to or smaller than the minimum refractive index (no) of the refractive index variable substance (liquid crystal) 5, the most typical optical glass in the above embodiment. An example using BK7 is given. However, the above embodiment is described using a conventional technique using total reflection at the interface between the light guide member and the liquid crystal as disclosed in Japanese Patent Application Laid-Open No. 2000-171814. When the same liquid crystal (E7) and incident angle (60 °) are applied, a light guide member having a refractive index of 1.76 or more must be used, leading to an increase in cost.
[0061]
(Embodiment 9)
FIG. 11 is a diagram for explaining a ninth embodiment of the present invention. This embodiment has the same configuration as that of the fifth embodiment except that a polymer dispersed liquid crystal is used as the refractive index variable material 5. The polymer dispersed liquid crystal is formed by dispersing liquid crystal droplets 26 in a polymer matrix 27. As the liquid crystal material, nematic liquid crystal, smectic liquid crystal, cholesteric liquid crystal, or the like can be used, and a single or two or more kinds of liquid crystal compounds or a mixture containing substances other than liquid crystal compounds may be used. The polymer matrix material is preferably a transparent polymer, and may be any of a thermoplastic resin, a thermosetting resin, and a photocurable resin.
[0062]
As a manufacturing method of polymer dispersed liquid crystal,
(1) A polymerization phase separation method in which a solution is made of liquid crystal and heat or photo-curing (polymerization) monomer, oligomer or prepolymer, and phase separation is performed by polymerization.
(2) Solvent evaporation phase separation method in which a solution is made with liquid crystal, polymer and solvent, and phase separation is performed by evaporating the solvent.
(3) A thermal phase separation method in which a liquid crystal and a thermoplastic polymer are dissolved by heating and then phase-separated by cooling.
Can be used.
[0063]
As the polymer, it is preferable to use an ultraviolet curable resin from the viewpoints of the ease of the production process and the separability from the liquid crystal phase. Specific examples include ultraviolet curable acrylic resins, and those containing an acrylic monomer and an acrylic oligomer that are polymerized and cured by ultraviolet irradiation are particularly preferable. Examples of such a monomer or oligomer include (poly) ester acrylate, (poly) urethane acrylate, epoxy acrylate, polybutadiene acrylate, silicone acrylate, melamine acrylate, and (poly) phosphazene methacrylate. As another example, a thiol-ene system can be suitably used because of its high photocuring speed.
[0064]
Photopolymerization initiators may be used for rapid polymerization, and examples include acetophenones such as dichloroacetophenone and trichloroacetophenone, 1-hydroxycyclohexyl phenyl ketone, benzophenone, Michler ketone, benzoyl, benzoin alkyl ether, benzyldimethyl ketal. And monosulfide, thioxanthones, azo compounds, diallyl iodonium salts, triallyl sulfonium salts, bis (trichloromethyl) triazine compounds, and the like.
[0065]
A liquid material in which a liquid crystal material is uniformly dissolved in the ultraviolet curable compound is injected between the reflecting member 15 and the light guide member 1 or the flat light guide 19, and then the ultraviolet curable compound is cured by irradiating with ultraviolet rays. At the same time, the liquid crystal material is phase-separated to form a polymer-dispersed liquid crystal layer.
[0066]
As an example of a specific polymer-dispersed liquid crystal, nematic liquid crystal BL24 (no = 1.513, ne = 1.717, Merck) is dissolved in UV curable prepolymer NOA81 (Norland) (liquid crystal weight concentration 45%). UV (400 mW / cm²) (The average particle diameter of the liquid crystal droplets is about 60 nm), the orientation of the droplets 26 in which the liquid crystal molecules are aligned is random in the case of FIG. The refractive index is approximately the volume of the average refractive index of liquid crystal (≈ (2no + ne) /3≈1.58) and the refractive index of polymer matrix 27 (≈1.56). It can be regarded as an average (≈1.57). In this case, the alignment treatment is not performed in advance. If the light guide member 1 is crown glass BK7 (nd = 1.517) and the incident angle is set to 75 °, the refraction angle is 69 °. Therefore, if α = 34.5 ° is set, the reflected light is incident on the light. The light enters the portion 3 almost perpendicularly. When β = 43 ° is set, the reflected light is φ with respect to the light emitting portion 4.₁Incident at 43 °. At this time, since Expression (2) is satisfied, the reflected light is totally reflected by the light emitting unit 4.
[0067]
In FIG. 11B, the liquid crystal molecules are arranged in the electric field direction, and the refractive index of the polymer dispersed liquid crystal layer with respect to S-polarized light is the refractive index of liquid crystal (≈no = 1.513) and the refractive index of the polymer matrix 27 ( ≈1.56) and volume average (≈1.54). At this time, the refraction angle is 72 °, and the reflected light is φ with respect to the light emitting portion 4.₁= 40 ° incident and outgoing angle φ₂Output at = 77 °.
[0068]
As above₂The angle φ incident on the light emitting portion 4 by increasing the amount of change₁Since the amount of change of can be increased, the state of total reflection and the state of not total reflection can be switched reliably, and a high S / N ratio can be obtained.
Further, the switching time between the state of FIG. 11A and the state of FIG. 11B is on the order of several tens of μs, and this value is about two orders of magnitude faster than the bulk liquid crystal.
The result of examining the relationship between the liquid crystal droplet size and the response speed in more detail is shown below. The size of the liquid crystal droplets in the polymer-dispersed liquid crystal can be changed by changing the composition of the prepolymer, the mixed concentration of the liquid crystal, the ultraviolet intensity during curing, and the like.
[0069]
FIG. 12 is a diagram showing the relationship between the liquid crystal droplet size and the response speed. E7 and BL24 (Merck) were used as the liquid crystal material, and NOA 60, 65 and 81 (Noland) were used as the prepolymer as appropriate.
FIG. 13 is a diagram showing an example of a response speed measuring device, in which 41 is a laser light source, 42 is a polarizer, 43 and 44 are lenses, 45 is an analyzer, 46 is a power meter, 47 is a sample, and 48 is a sample. An Au electrode, 49 is a polymer dispersed liquid crystal layer, and 50 is a Si substrate. In this measurement, the total of the rise time (Ton) and fall time (Toff) of the light output when a pulse voltage (200 V) was applied to the sample 47 was measured. In the sample 47, the thickness of the polymer dispersed liquid crystal layer 49 was 20 μm, and the optical path length was 1 mm.
[0070]
FIG. 14 is a diagram schematically showing a state in which an electric field is not applied to the polymer-dispersed liquid crystal and a state in which it is applied. When no electric field is applied, the orientation of the liquid crystal droplets 26 is random as shown in FIG. 14A, so that the refractive indexes in the x-axis, y-axis, and z-axis directions are all equal, and the entire layer is It is an optically isotropic medium. When an electric field 28 is applied in the z direction, as shown in FIG. 14B, the molecular axes of the liquid crystal molecules in the liquid crystal droplet 26 are aligned in this direction, so that the refractive index in the z axis direction increases, and the x axis and y The magnitudes of the axial refractive indexes remain small while remaining equal to each other.
[0071]
As shown in FIG. 13, when the light from the laser light source 41 is incident from the x direction perpendicular to the electric field direction, the polarization state can be changed because birefringence occurs in the yz plane. The light output passed through changes. In the present invention, such a birefringence phenomenon is not used, but the response speed of FIG. 12 can be similarly applied to the present invention because the behavior of the liquid crystal molecules at the time of applying an electric field and the accompanying change in the refractive index are used. FIG. 12 shows that the response speed increases as the liquid crystal droplet size decreases.
[0072]
Furthermore, it is preferable from the viewpoint of light transmittance that the particle size of the liquid crystal droplets is 1/5 or less of the wavelength of incident light, more preferably 1/10 or less. The result of calculating the light transmittance from the Rayleigh scattering theory is shown below. When a spherical scatterer with a volume V exists at a number density N, the light transmittance T of a medium with a thickness L is expressed by the following equation (3). T = exp (−NRL), R = 24π^Three((M²-1) / (m²+2))²V²/ Λ^Four
... (3)
In Equation (3), R is the scattering cross section, m is the ratio of the refractive index of the scatterer to the refractive index of the medium, and λ is the wavelength of the light used. The transmittance T when m = 1.07 and L = 100 μm was calculated using the particle size d, volume fraction (= NV) and wavelength λ of the scatterer, ie, liquid crystal droplets, as parameters. As can be seen from Equation (3), T decreases as d increases (that is, V increases) and λ decreases. The transmittance is preferably 90% (T = 0.9) or more from the viewpoint of light utilization efficiency.
[0073]
FIG. 15 shows that the particle size at which T = 0.9 is 10% (d (0.1)), 30% (d (0.3)) and 50% (d (0.5)). Is a graph plotted with respect to wavelength. If the volume fraction is small, the amount of change in refractive index is small and the S / N ratio cannot be obtained. Therefore, the volume fraction is preferably 10% or more, more preferably about 50%. If the volume fraction is higher than this, the production becomes extremely difficult. From this point of view, as shown in FIG. 15, d is preferably λ / 5 or less and more preferably λ / 10 or less with respect to the wavelength in the visible to infrared region applied as the optical path switching element. In this calculation, m and L are fixed, but it is considered that the actual device has a value smaller than this, so there is no problem as long as the particle size is in the above range.
[0074]
(Embodiment 10)
FIG. 16 is a diagram for explaining a tenth embodiment of the present invention. This embodiment has the same configuration as that of the seventh embodiment except that all the liquid crystal molecules in the liquid crystal droplet 26 are aligned in approximately one direction when no voltage is applied (in FIG. 16A). Have This arrangement direction is substantially orthogonal to the direction (electric field direction) in which liquid crystal molecules are aligned when a voltage is applied (in FIG. 16B), and is a direction that is horizontal to the light incident portion 3 of the light guide member 1 and perpendicular to the paper surface. It is good to make it. By doing this, a large refractive index difference is obtained, so θ₂Can be increased, and a high S / N ratio can be obtained. Specifically, when a polymer-dispersed liquid crystal having the same material and formulation as in the sixth embodiment is used, the refractive index of the polymer-dispersed liquid crystal layer is the refractive index of the liquid crystal (≈ne) as shown in FIG. = 1.717) and the refractive index (≈1.56) of the polymer matrix 27 can be regarded as a volume average (≈1.61). When the incident angle is set to 75 ° as in the sixth embodiment, the refraction angle is 66 °. Therefore, when α = 33 ° is set, the reflected light enters the light incident portion 3 almost perpendicularly. When β = 43 ° is set, the reflected light is φ with respect to the light emitting portion 4.₁Incident at 43 °. At this time, since Expression (2) is satisfied, the reflected light is totally reflected by the light emitting unit 4.
[0075]
In the case of FIG. 16B, the liquid crystal molecules are arranged in the electric field direction, and the refractive index of the polymer dispersed liquid crystal layer with respect to S-polarized light is the refractive index of liquid crystal (≈no = 1.513) and the refractive index of the polymer matrix 27 ( ≈1.56) and volume average (≈1.54). At this time, the refractive index is 72 °, and the reflected light is φ with respect to the light emitting portion 4.₁= Incident at 37 °, outgoing angle φ₂Output at = 66 °.
[0076]
θ₂The angle φ incident on the light emitting portion 4 by increasing the amount of change₁Since the amount of change of can be increased, the state of total reflection and the state of not total reflection can be switched reliably, and a high S / N ratio can be obtained.
When the incident angle is set to 60 °, the refraction angle θ is as shown in FIG.₂Is 55 °. At this time, if α = 27.5 ° and β = 43 ° are set, φ in FIG.₁= 39 °, φ₂= 73 °. In particular, when applied to a two-dimensional spatial light modulator and an image display apparatus using the same as described later, a smaller incident angle (preferably 60 ° or less) is desirable because the design of the illumination optical system becomes easier. .
[0077]
As a method for aligning liquid crystal molecules in one direction in advance, it is also possible to use the following method in addition to the method using the alignment film as described above. The liquid crystal can be aligned in one direction by applying an electric field when polymerizing the polymer matrix material. At this time, the prepolymer in contact with the liquid crystal is dragged by the alignment of the liquid crystal and is aligned in the same direction. When the prepolymer is polymerized in this state, the interface with the liquid crystal is fixed in a form following the alignment of the liquid crystal. Since this interface structure functions as an alignment film for the liquid crystal, even if the electric field is released after the polymer matrix material is cured, the liquid crystal is aligned in the direction of the electric field applied during polymerization.
[0078]
(Embodiment 11)
FIG. 17 is a diagram for explaining an eleventh embodiment of the present invention, in which 60 is a one-dimensional spatial light modulator, and FIG. 17A is a schematic perspective view of the one-dimensional spatial light modulator 60. FIG. 17B is a schematic configuration diagram when FIG. 17A is viewed from the B direction, and FIG. 17C is a schematic configuration diagram when FIG. 17A is viewed from the C direction. The basic configuration of this embodiment is the same as that of the seventh embodiment, but the metal films 7 also serving as individual electrodes are arranged in a one-dimensional array. The substrate 9 is preferably provided with driving elements connected to the individual electrodes and selectively supplying signals to them. By selectively applying a voltage signal to each individual electrode arranged in an array, only the reflected light from the selected individual electrode (metal film 7) is emitted from the light emitting unit 4, and the line-shaped light is turned on. / OFF (spatial light modulation) is possible. Two-dimensional spatial light modulation can be performed by combining with a scanning device that scans in a direction perpendicular to the direction in which the individual electrodes are arranged.
[0079]
In addition, as shown in FIG. 18, driving signal supply to the individual electrodes (metal film 7) of the one-dimensional spatial light modulator 60 and driving of the scanning mechanism 63 including a galvano mirror are controlled based on the image signal. By projecting the two-dimensional spatial light modulated light beam onto the screen 65 by the projection lens 64, an image display device can be formed. In FIG. 18, a laser, LED, lamp, or the like can be used as the light source 61. Further, the collimator lens 62 may be an optical integrator, and a polarization conversion optical system (not shown) may be provided at the subsequent stage.
[0080]
(Embodiment 12)
FIG. 19 is a diagram for explaining a twelfth embodiment of the present invention, and FIG. 19 is a schematic perspective view of a two-dimensional spatial light modulator 70. The basic configuration of this embodiment is the same as that of FIG. 17, but the metal films 7 also serving as individual electrodes are arranged in a two-dimensional array. The reflecting member 15 is preferably provided with a driving element that is connected to each individual electrode and selectively supplies signals thereto. By selectively applying a voltage signal to the individual electrodes arranged in an array, only the reflected light from the selected individual electrode (metal film 7) is emitted from the light emitting unit 4, and the planar light is turned on. / OFF (spatial light modulation) is possible. In this case, since the two-dimensional spatial light modulation can be performed only by the spatial light modulator, the scanning mechanism 63 as shown in FIG. 18 is unnecessary, and the projection lens 64 is installed outside the light emitting unit 4 and the screen 65 is provided. By projecting, an image display device can be formed.
[0081]
In the example shown in FIGS. 17 and 19, the light guide member 1 is shared and formed as one, but the light guide member 1 may be divided for each optical path switching element. In addition, in the image display device using the one-dimensional array-shaped spatial light modulator or the two-dimensional array-shaped spatial light modulator, incident light of a plurality of wavelengths such as red, green, and blue is used, and each color is divided in a time division manner. A full color image can also be displayed by displaying an image (field sequential method) or by providing a plurality of spatial light modulators and simultaneously projecting images of each color.
[0082]
Example 1
FIG. 20 is a diagram for explaining an example of the manufacturing process of the two-dimensional spatial light modulator. The two-dimensional spatial light modulator was manufactured as follows.
(1) Production of reflecting member (FIG. 20A)
A plurality of MOSFET drive elements 51 were formed on the surface of the Si substrate 9, and an oxide film (insulator 8) of 5 μm thick silicon oxide was deposited thereon by CVD. Next, the inclined surface and the contact hole 52 were formed by performing patterning and dry etching using a photomask in which an area gradation pattern was formed. After filling the hole by metal CVD, aluminum was deposited to a thickness of 0.1 μm by sputtering and patterned to be a reflective film and individual electrode (metal film 7). A polyimide film having a thickness of 0.1 μm was formed thereon by spin coating, and an alignment film 53 was formed by rubbing.
[0083]
(2) Production of cell (FIG. 20B)
A transparent light guide 10 made of ITO having a thickness of 50 nm and an alignment film 54 made of polyimide are formed on one surface of a flat light guide 19 made of crown glass (BK7), and the reflecting member shown in FIG. An empty cell was produced by bonding using a sealing material 11 made of resin. An injection hole was provided in a part of the sealing material.
[0084]
(3) Injection of liquid crystal (FIG. 20C)
After evacuating the empty cell shown in FIG. 20 (C), the refractive index variable material 5 made of liquid crystal (E7) was injected to seal the injection hole.
[0085]
(4) Joining of light guide members (FIG. 20D)
The light guide member 1 and the second light guide member 17 were joined to the upper surface of the flat light guide 19 using a photocurable adhesive.
Using the spatial light modulator manufactured as described above, image display was performed as follows.
Laser light (wavelengths of 633 nm, 532 nm, and 488 nm) shaped so that the cross section is substantially rectangular was incident as S-polarized light from the light incident portion 3. The incident angles of the respective lasers with respect to the incident light capturing unit 16 were 0 °, 0.5 °, and 1 °, respectively. When a voltage (5 V) is selectively applied to the individual electrode (metal film 7) according to the image data by the driving element 51, the spatially modulated output light is extracted from the second light emitting unit 18 (not shown) ) An enlarged projection image (binary) having no color shift at each wavelength could be obtained on the screen by the projection lens.
[0086]
(Example 2)
FIG. 21 is a diagram for explaining another example of the manufacturing process of the two-dimensional spatial light modulator. The two-dimensional spatial modulator was manufactured as follows.
(1) Production of reflecting member (FIG. 21A)
A plurality of MOSFET drive elements 51 were formed on the surface of the Si substrate 9, and an oxide film (insulator 8) of 5 μm thick silicon oxide was deposited thereon by CVD. Next, the inclined surface and the contact hole 52 were formed by performing patterning and dry etching using a photomask in which an area gradation pattern was formed. After filling the hole by metal CVD, aluminum was deposited to a thickness of 0.1 μm by sputtering and patterned to be a reflective film and individual electrode (metal film 7). A polyimide film having a thickness of 0.1 μm was formed thereon by spin coating, and an alignment film 53 was formed by rubbing.
[0087]
(2) Cell fabrication (FIG. 21B)
A transparent light source 10 made of ITO having a thickness of 50 nm and an alignment film 54 made of polyimide are formed on one surface of a flat light guide 19 made of crown glass (BK7), and the reflecting member shown in FIG. An empty cell was produced by bonding using a sealing material 11 made of resin. An injection hole was provided in a part of the sealing material.
[0088]
(3) Injection (FIG. 21C)
After evacuating the empty cell shown in FIG. 21B, a mixture (liquid crystal concentration 45 wt%) 55 of liquid crystal (BL24) and an ultraviolet curable compound (NOA81) was injected to seal the injection hole.
(4) Curing (FIG. 21D)
UV light (400mW / cm by high pressure mercury lamp²) 56 was irradiated to form a refractive index variable substance 5 made of polymer dispersed liquid crystal.
[0089]
(5) Joining of light guide members (FIG. 21E)
The light guide member 1 and the second light guide member 17 were joined to the upper surface of the flat light guide 19 using a photocurable adhesive.
Using the spatial light modulator manufactured as described above, image display was performed as follows.
Laser light (wavelengths of 633 nm, 532 nm, and 488 nm) shaped so that the cross section is substantially rectangular was incident as S-polarized light from the light incident portion 3. The incident angles of the respective lasers with respect to the incident light capturing unit 16 were 0 °, 0.5 °, and 1 °, respectively. When a voltage (5 V) is selectively applied to the individual electrode (metal film 7) according to the image data by the driving element 51, the spatially modulated output light is extracted from the second light emitting unit 18 (not shown) ) An enlarged projection image (64 tone) having no color shift at each wavelength could be obtained on the screen by the projection lens.
[0090]
【The invention's effect】
As is apparent from the above description, according to the optical path switching element of the present invention, the light incident part through the light guide member, the reflection part that reflects the incident light entering from the light incident part, and the reflection part is reflected. A light emitting part that emits the emitted light as outgoing light through the light guide member, encapsulating a refractive index variable substance in an optical path including the reflecting part, and depending on the information on the refractive index variable substance A signal input means for providing a signal and causing a change in refractive index, and a change in the refractive index of the refractive index variable material due to the signal, the incident light is totally reflected at the interface between the light guide member and the refractive index variable material. By providing a means for controlling the direction of the outgoing light according to the wavelength of the incident light in the optical path switching element that is not in the range, the structure is simple and durable, the member cost can be reduced, the light utilization efficiency is high, the incident light Depending on the wavelength of light It is possible to provide a high optical path switching element without S / N ratio.
[0091]
In addition, the means for controlling the direction of the emitted light according to the wavelength of the incident light is an incident light adjusting mechanism that adjusts the incident angle and the incident position of the incident light to the light guide member according to the wavelength of the incident light. It is possible to provide an optical path switching element that can prevent an optical path shift without requiring a complicated control mechanism.
[0092]
In addition, since the means for controlling the direction of the emitted light according to the wavelength of the incident light is a bias applying mechanism for applying a bias voltage to the refractive index variable substance according to the wavelength of the incident light, a complicated control mechanism is required. Therefore, it is possible to provide an optical path switching element that can prevent an optical path shift without being caused.
[0093]
In addition, the refractive index change of the refractive index variable substance due to the signal is not totally reflected in the first state where the light reflected by the reflecting part is totally reflected at the interface between the light guide member and the external substance in contact with the light emitting part. By performing in the range which can take a 2nd state, the optical path switching element which can raise S / N ratio more can be provided. Further, by configuring the light incident part and the light emitting part with surfaces that are not parallel to each other, it is possible to provide an optical path switching element that can further increase the S / N ratio. In addition, by providing a second light emitting portion that can emit the emitted light to the outside through the second light guide member, an optical path switching element having a high S / N ratio can be provided.
[0094]
In addition to the above, an optical path switching element that is easy to manufacture can be provided by optically joining the light guide member and providing a flat light guide having substantially the same refractive index as the light guide member. Further, the reflection part is configured by two surfaces sharing one side, and the maximum value in the operating range of the angle formed by the incident light that has entered the refractive index variable material and the normal of the surface that constitutes the light incident part is θ_2maxThe angle between the normal of at least one surface constituting the reflecting portion and the normal of the surface constituting the light incident portion is 90 ° −θ._2maxBy making it below, the optical path switching element which can make drive energy small can be provided. In addition, it is possible to provide an optical path switching element capable of further reducing driving energy by configuring the reflecting section to have a plurality of sets of surfaces for the unit element that applies a signal to the refractive index variable substance.
[0095]
In addition, by using a liquid crystal as the refractive index variable substance, it is possible to provide an optical path switching element that is easier to manufacture and that can increase the S / N ratio. In addition to the above, by providing a liquid crystal / polymer composite (polymer dispersed liquid crystal) in which the refractive index variable substance is a liquid crystal material dispersed and held in a polymer matrix, an optical path switching element having a high response speed is provided. Can do. In addition to the above, an optical path switching element with a small optical loss is provided by configuring the refractive index variable material with a polymer dispersed liquid crystal and making the liquid crystal a droplet having a particle size of 1/5 or less of the wavelength of incident light. can do.
[0096]
In addition to the above, the S / N ratio can be further increased by configuring the refractive index variable substance with polymer dispersed liquid crystal so that all liquid crystal molecules are arranged in approximately one direction when no voltage is applied. An optical path switching element can be provided.
[0097]
Furthermore, by arranging the optical path switching elements of the present invention in a one-dimensional or two-dimensional array, a spatial light modulator having a simple structure, high durability, reduced member cost, and high light utilization efficiency is provided. Can do.
[Brief description of the drawings]
FIG. 1 is a diagram for explaining a first embodiment of the present invention.
FIG. 2 is a diagram for explaining an example in which the emission direction of light of different wavelengths changes.
FIG. 3 is a diagram for explaining an example of an incident light adjusting mechanism.
FIG. 4 is a diagram for explaining a second embodiment of the present invention.
FIG. 5 is a diagram for explaining a third embodiment of the present invention.
FIG. 6 is a diagram for explaining a fourth embodiment of the present invention.
FIG. 7 is a diagram for explaining a fifth embodiment of the present invention.
FIG. 8 is a diagram for explaining a sixth embodiment of the present invention.
FIG. 9 is a diagram for explaining a seventh embodiment of the present invention.
FIG. 10 is a diagram for explaining an eighth embodiment of the present invention.
FIG. 11 is a diagram for explaining a ninth embodiment of the present invention.
FIG. 12 is a diagram showing a relationship between a liquid crystal droplet size and a response speed.
FIG. 13 is a diagram showing an example of a response speed measuring device.
FIG. 14 is a diagram schematically showing a state where an electric field is not applied to a polymer-dispersed liquid crystal and a state where it is applied.
FIG. 15 is a graph in which the particle diameter at which T = 0.9 is plotted with respect to wavelength when the volume fraction is 10%, 30%, and 50%.
FIG. 16 is a diagram for explaining a tenth embodiment of the present invention.
FIG. 17 is a diagram for explaining an eleventh embodiment of the present invention;
FIG. 18 is a schematic diagram illustrating a configuration example of an image display device of the present invention.
FIG. 19 is a diagram for explaining a twelfth embodiment of the present invention.
FIG. 20 is a diagram for explaining an example of a manufacturing process of a two-dimensional spatial light modulator.
FIG. 21 is a diagram for explaining another example of the manufacturing process of the two-dimensional spatial light modulator.
FIG. 22 is a plan view of a spatial light modulator described in Japanese Patent Laid-Open No. 5-196880.
23 is a cross-sectional view of one rotating mirror of the spatial light modulator shown in FIG.
FIG. 24 is an explanatory diagram of the operation of the optical switching element proposed in Japanese Patent Laid-Open No. 11-202222.
FIG. 25 is a diagram showing a schematic configuration of an optical switching element proposed in Japanese Patent Application Laid-Open No. 2000-171813.
FIG. 26 is a diagram showing an example of an optical path switching element described in Japanese Patent Application No. 2001-187577.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Light guide member, 2 ... External substance, 3 ... Light incident part, 4 ... Light emitting part, 5 ... Refractive index variable substance, 6 ... Reflection part, 7 ... Metal film, 8 ... Insulator, 9 ... Substrate, 10 DESCRIPTION OF SYMBOLS ... Transparent electrode, 11 ... Sealing material, 12 ... Liquid crystal molecule, 13 ... Photodetector, 15 ... Reflecting member, 16 ... Incident light taking-in part, 17 ... Second light guide member, 18 ... Second light emitting part , 19 ... Flat light guide, 22 ... Drive signal generator, 23 ... Bias signal generator, 24 ... Reflecting surface, 25 ... Reversely inclined surface, 26 ... Liquid crystal droplet, 27 ... Polymer matrix, 28 ... Electric field, 30 DESCRIPTION OF SYMBOLS ... Optical path switching element, 31 ... Reflective element, 33 ... Light source, 41 ... Laser light source, 42 ... Polarizer, 43, 44 ... Lens, 45 ... Analyzer, 46 ... Power meter, 47 ... Sample, 48 ... Au electrode, 49 ... polymer dispersed liquid crystal layer, 50 ... Si substrate, 51 ... drive element, 52 ... contact photo 53, 54 ... alignment film, 55 ... mixture, 56 ... UV light, 60 ... one-dimensional spatial light modulator, 61 ... light source, 62 ... collimating lens, 63 ... scanning mechanism, 64 ... projection lens, 65 ... screen, 70 ... Two-dimensional spatial light modulator, 71 ... Square torsion beam reflecting surface, 72 ... Beam support post, 73 ... Hinge, 74 ... Ground electrode, 75 ... Post, 76 ... Post, 77 ... Address electrode, 78 ... Metal layer, 79 DESCRIPTION OF SYMBOLS ... Board | substrate layer, 81 ... Light guide member, 82 ... Total reflection surface, 91 ... Prism, 91a ... Reflection surface of prism, 92 ... Extraction surface, 100 ... Drive part, 101 ... Light beam, 102 ... Total reflection light, 103 ... Light beam 110 ... light guide, 111 ... transparent electrode, 112 ... incident light (linearly polarized light), 113 ... total reflected light, 114 ... reflected light, 120 ... liquid crystal, 121 ... reflective film, 130 ... IC substrate for driving liquid crystal, 1 1 ... electrode terminal.

Claims (13)

A light incident part for allowing light incident through the light guide member to enter the refractive index variable material;
A reflecting portion for reflecting incident light that has entered the refractive index variable material from the light incident portion;
It consists of a light emitting part that emits to the outside as emitted light through the light guide member,
Encapsulating the refractive index variable substance in an optical path including the reflective portion;
In the optical path switching element comprising signal input means for giving a signal to the refractive index variable substance according to information and causing a refractive index change,
The refractive index change of the refractive index variable substance due to the signal is performed in a range where the incident light is not totally reflected at the interface between the light guide member and the refractive index variable substance, and the emitted light depends on the wavelength of the incident light. of so that the optical path is not shifted, a means for controlling the emitted light direction depending on the wavelength of the incident light,
The means for controlling the outgoing light direction according to the wavelength of the incident light is an incident light adjusting mechanism for adjusting the incident angle and the incident position of the incident light to the light guide member according to the wavelength of the incident light. A characteristic optical path switching element. A light incident part for allowing light incident through the light guide member to enter the refractive index variable material;
A reflecting portion for reflecting incident light that has entered the refractive index variable material from the light incident portion;
It consists of a light emitting part that emits to the outside as emitted light through the light guide member,
Encapsulating the refractive index variable substance in an optical path including the reflective portion;
In the optical path switching element comprising signal input means for giving a signal to the refractive index variable substance according to information and causing a refractive index change,
The refractive index change of the refractive index variable substance due to the signal is performed in a range where the incident light is not totally reflected at the interface between the light guide member and the refractive index variable substance, and the emitted light depends on the wavelength of the incident light. Means for controlling the direction of the emitted light according to the wavelength of the incident light, so that the optical path of
Said means for controlling the emitted light direction depending on the wavelength of incident light, you being a biasing mechanism for applying a bias signal to the variable refractive index material according to the wavelength of the incident light optical path switching element . A first state in which the light reflected by the reflecting part is totally reflected at the interface between the light guide member and an external substance in contact with the light emitting part in the refractive index change of the refractive index variable substance due to the signal; 3. The optical path switching element according to claim 1, wherein the optical path switching element is performed within a range where the second state in which total reflection is not achieved can be taken. Optical path switching element according to any one of claims 1 to 3, characterized in that said light incident portion and the light emitting portion is constituted by a surface not parallel to each other. Optical path switching element according to any one of claims 1 to 4, characterized in that a second light emitting portion that can be issued to the outside the light emitted through the second light guide member. Optically bonded to the light incident portion, the light path switching device according to any one of claims 1 to 5 wherein the light guide member and the refractive index is characterized in that a approximately equal photoconductive member. The reflection part is constituted by two surfaces sharing one side, and the maximum value in the operating range of the angle formed by the incident light that has entered the refractive index variable material and the normal of the surface that constitutes the light incident part is θ _2max Then, an angle formed by a normal line of at least one surface constituting the reflection portion and a normal line of the surface constituting the light incident portion is 90 ° −θ _2max or less. optical path switching element according to any one of 6. The optical path switching according to any one of claims 1 to 7 , wherein the reflection unit has a plurality of sets of surfaces with respect to a unit element that applies a signal to the refractive index variable substance. element. Optical path switching device according to any one of claims 1 to 8 wherein the variable refractive index material is characterized by comprising the liquid crystal. Optical path switching device according to any one of claims 1 to 8 wherein the variable refractive index material is characterized by comprising a liquid crystal material from the liquid crystal / polymer composite dispersed held in a polymer matrix. The optical path switching element according to claim 10 , wherein the liquid crystal material is a droplet having a particle size equal to or less than 1/5 of a wavelength of incident light. The optical path switching element according to any one of claims 9 to 11 , wherein all liquid crystal molecules are arranged in approximately one direction when no voltage is applied. Spatial light modulator, wherein the optical path switching elements are arranged in a one-dimensional array or two-dimensional array according to any one of claims 1 to 12.

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