JP4370856B2 - Hologram imaging device - Google Patents

Description

  The present invention relates to a hologram imaging element using a photosensor.

  Conventionally, a holography technique using a hologram has been widely used as one of means for displaying a stereoscopic image. This holographic technique has an advantage that a very natural stereoscopic effect can be given to an observer as compared with a method of obtaining a stereoscopic image by changing the viewing angle using two or more cameras.

In the holography technique described above, for example, as shown in Patent Document 1, light emitted from the same light source is divided into two optical paths through a light separation means such as a half mirror, and one of the objects is imaged and irradiated. The reflected light is image signal light representing the target object (hereinafter referred to as object light), and the other is used as reference light including only wavefront information (phase information) of the light source. By recording the light intensity (amplitude) and phase information as hologram information, and irradiating the recording medium on which the hologram information is stored again with reference light, the hologram information is reproduced using the diffraction phenomenon. (See Patent Document 1).
JP 10-31147 A

  In the case of the above-described conventional holography technology, optical elements are adjusted by arranging optical elements such as various lenses and slits in order to form a desired interference fringe on the recording medium. Adjustment and setting are difficult.

  It is an object of the present invention to provide a hologram imaging device that has a simplified optical path configuration and can be easily adjusted and set.

  A hologram imaging element of the present invention includes a semiconductor layer that generates electron-hole pairs by incidence of light on a substantially transparent insulating substrate, and a source electrode and a drain that are electrically connected to both ends of the semiconductor layer. A plurality of photosensors each including an electrode and a gate electrode arranged to face at least a central portion of the semiconductor layer via an insulating layer are arranged in a predetermined arrangement with a substantially transparent insulating layer interposed therebetween. The photosensor array that forms the sensor array surface and coherent light are emitted, the emitted light is incident on the insulating substrate of the photosensor array, is transmitted between the photosensors, and is emitted from the sensor array surface. A light source unit to be opposed to the sensor array surface of the photosensor array, and a part of the light emitted from the sensor array surface is reflected toward the sensor array surface. The reference light and the irradiation light that transmits the other part of the emitted light and irradiates the imaging target, and the object light reflected by the imaging target of the irradiation light, and the reference And light separating and projecting means for forming interference fringes on the sensor array surface by light.

  According to the hologram imaging element of the present invention, a photosensor array that can partially transmit light is used as a recording medium, and light source light is incident from the surface (back surface) opposite to the sensor array surface and emitted to the surface side. The light separating and projecting means provided on the surface side separates the irradiation light on the object and the reference light, the reference light is reflected to the photosensor array, the irradiation light is irradiated on the object, and the reflected light is The object light is projected onto the photosensor array, and a hologram consisting of these reference light, object light, and interference fringes is formed on the sensor array surface, so the optical path configuration is extremely simplified, easy to operate and reliable. An excellent hologram imaging device can be provided at a lower cost.

  In the hologram image pickup device of the present invention, the light separating and projecting means includes a reflection polarizing plate having a transmission axis and a reflection axis orthogonal to each other, and an object light transmitted through the reflection polarizing plate and reflected by the imaging object in a vibration direction. Is laminated with an optical element such as a phase difference plate that is linearly polarized along the transmission axis of the reflective polarizing plate, and the reflective polarizing plate faces the sensor array surface of the photosensor array. It is preferable to dispose the object light so that the object light can be projected onto the photosensor without loss, and clear hologram information can be efficiently obtained.

  The light separating and projecting means includes a light diffusing layer laminated on a transflective plate that reflects a part of incident light and transmits another part, and the light diffusing layer is a sensor of a photo sensor array. It is preferable to arrange so as to face the array surface, and thereby the structure of the hologram imaging element is further simplified.

  Furthermore, it is preferable that the photosensor has a double gate type thin film transistor structure in which gate electrodes are arranged one by one with a semiconductor layer interposed therebetween, and this makes it possible to acquire hologram information with higher sensitivity.

  FIG. 1 is a conceptual diagram showing an overall configuration of a hologram imaging element as an embodiment of the present invention, and FIG. 2 is a partially enlarged sectional view showing a detailed configuration of a main part Q thereof.

  As shown in FIG. 1, the hologram imaging element of the present embodiment sandwiches a photosensor array plate Aps in which a plurality of photosensors 2 are arranged on one main surface of a transparent glass substrate 1 at a predetermined interval. On the sensor array surface side (hereinafter referred to as the front surface side), an optical laminated body Osp formed by laminating a reflective polarizing plate 3 and a λ / 2 phase difference plate 4 as a light separating and projecting means is disposed to face the glass substrate 1. A light source unit Ls including a light source 5 that emits coherent light, a condensing lens 6 that collects the emitted light, a pinhole 7, and a collimator lens 8 for obtaining a parallel light beam is disposed on the side, that is, the back side. Configured. When hologram information is picked up by this hologram image pickup element, the λ / 2 phase difference plate 4 side of the optical laminate Osp is made to face, for example, the doll f of the image pickup object.

First, the configuration of the photo sensor array plate Aps will be described based on the configuration explanatory diagrams of FIGS.
In the photosensor array plate Aps of this embodiment, each photosensor 2 on which hologram information is written is arranged on a substantially transparent glass substrate 1 that transmits visible light at a predetermined interval in a matrix as shown in FIG. The sensor array portion Sa is formed by being arranged so as to be arranged, and various drivers for operating the respective photosensors 2 are arranged around the sensor array portion Sa.

Each photosensor 2 is formed in a double gate type thin film transistor structure as shown in FIG.
That is, each photosensor 2 uses the semiconductor layer 20 that generates electron-hole pairs upon incidence of light as a common channel region, the semiconductor layer 20, the source electrode 22, the drain electrode 23, the top gate insulating film 25, and An upper MOS transistor formed by the top gate electrode 26 and a lower MOS transistor formed by the semiconductor layer 20, the source electrode 22, the drain electrode 23, the bottom gate insulating film 27, and the bottom gate electrode 28 are formed on the glass substrate 1. Formed. Reference numeral 21 denotes an ohmic contact layer that electrically connects the source electrode 22 and drain electrode 23 and the semiconductor layer 20, 24 denotes a blocking insulating layer that protects the semiconductor layer 20, and 29 denotes a sensor array portion Sa (see FIG. 3). It is a protective insulating film that covers and protects the whole.

  Thus, in the present embodiment, since the photosensor 2 is formed in a double gate type thin film transistor structure, the channel formation of the semiconductor layer 20 by the electric field of the bottom gate electrode 28 is controlled by the electric field from the top gate electrode 26, and the semiconductor The drain current flowing when the layer 20 is not irradiated with light (in the dark) becomes extremely small. As a result, a sufficiently large difference between the drain currents during the light irradiation (in the bright time) and in the dark can be ensured. It can be a photo sensor.

  Here, the protective insulating film 29, the top gate insulating film 25, the blocking insulating layer 24, and the bottom gate insulating film 27 are made of a light-transmitting insulating film such as silicon nitride, and the top gate electrode 26 and the top that is the lead wiring thereof. The gate lines are made of a light-transmitting conductive material such as ITO (Indium Tin Oxide), and both show high light transmittance. On the other hand, the source electrode 22, the drain electrode 23, the bottom gate electrode 28, and the source lines, drain lines, and bottom gate lines of the lead wires are made of a light-shielding material such as chromium, aluminum, or an alloy thereof. Therefore, light is not transmitted to the arrangement portion of each photosensor 2 from the back side by the bottom gate electrode 28, but light is transmitted between the photosensors 2 with high transmittance. .

  Returning to FIG. 3, the driver unit disposed around the sensor array unit Sa includes a bottom gate driver Dbg, a top gate driver Dtg, a drain driver Dd, and a controller Cd. The controller Cd outputs a control signal CNT to the bottom gate driver Dbg and the top gate driver Dtg, respectively, and causes each gate electrode 26, 28 to output a signal of a predetermined level at a predetermined timing for each row. The state of the sensor 2 is sequentially changed to a reset state, a photo sensing state, and a reading state for each row. Then, the drain driver Dd reads out the potential change of the drain line of the photosensor 2 in the readout state, and sequentially captures this as the hologram data signal DATA.

  Returning to FIG. 2, the reflective polarizing plate 3 facing the front side of the photosensor array plate Aps configured as described above is an optical element having a polarization axis and a reflection axis orthogonal to each other, and the incident light R The component light R1 oscillating in the direction along the transmission axis is transmitted, and the component light R2 oscillating in the direction along the reflection axis is reflected.

  On the surface opposite to the side facing the photo sensor array plate Aps of the reflective polarizing plate 3, that is, the front surface, the λ / 2 phase difference plate 4 is superposed. The λ / 2 phase difference plate 4 is an optical element that imparts a phase difference of ½ of its wavelength to transmitted light.

  On the other hand, on the glass substrate 1 side or back side of the photosensor array plate Aps, as shown in FIG. 1, a semiconductor laser as a light source 5 for emitting coherent light and a condenser lens 6 for condensing the emitted light, And a collimator lens 8 for obtaining a parallel beam is arranged with the optical axis aligned, and a pinhole 7 is arranged between the condenser lens 6 and the collimator lens 8 with the hole 7a positioned at the focal point of the collimator lens 8. Thus, the light source unit Ls is configured.

Next, a hologram imaging operation by the hologram imaging element configured as described above will be described.
The laser light emitted radially from the semiconductor laser 5 is focused by the condenser lens 6 toward the hole 7a of the pinhole 7, and the light passing through the hole 7a is diffused again and enters the collimator lens 8. The light incident on the collimator lens 8 is emitted as parallel light here, and irradiates the photo sensor array plate Aps from its back surface.

  Of the light irradiated on the back surface of the photosensor array plate Aps, the light incident between the photosensors 2 has a high light transmittance. The glass substrate 1 and the bottom gate insulating film 27, the top gate insulating film 25, and The protective insulating film 29 is sequentially transmitted and emitted to the opposite side. The emitted light R is incident on the reflective polarizing plate 3 disposed so as to face the light. Here, the linearly polarized light R1 of the component light that vibrates in the direction along the transmission axis of the incident light is transmitted and overlapped on the front side thereof. The linearly polarized light R2 of the component light that enters the provided λ / 2 phase difference 4 and vibrates in the direction along the reflection axis is reflected to the photosensor array plate Aps side.

  The linearly polarized light R2 reflected by the reflective polarizing plate 3 is projected as reference light on the sensor array surface (front surface) of the photosensor array plate Aps.

  On the other hand, the linearly polarized light that has been transmitted through the reflective polarizing plate 3 and incident on the λ / 2 phase difference plate 4 is given a phase difference of ½ of its wavelength when transmitted through the λ / 2 phase difference plate 4. Is emitted as linearly polarized light R1 that differs by 90 °, and is projected onto the kokeshi doll f to be imaged. The linearly polarized light R1 is reflected by the surface of the imaging object and becomes linearly polarized light R1 ′ as object light including the image signal of the imaging object, and is incident on the λ / 2 phase difference plate 4 again and transmitted therethrough. Further, a phase difference of ½ of the wavelength is given to the linearly polarized light whose vibration direction is along the transmission axis of the reflective polarizing plate 3. The linearly polarized light passes through the reflective polarizing plate 3 as it is and is projected as object light on the sensor array surface of the photosensor 2 on which the reference light is projected. In this case, since the vibration direction of the linearly polarized light R1 ′ that has become the object light is aligned with the transmission axis direction of the reflective polarizing plate 3 through the λ / 2 phase difference plate 4, the linearly polarized light R1 ′ of the object light is lost. The reflective polarizing plate 3 can be efficiently emitted and projected onto the sensor array surface.

  As described above, on the sensor array surface on which the reference light R2 and the object light R1 ′ are projected, these interfere with each other to form interference light and form interference fringes. This interference fringe information, that is, hologram data is acquired as light intensity distribution data of interference light detected by each photosensor 2. That is, a channel is formed by irradiating the semiconductor layer 20 of each photosensor 2 with interference light, the magnitude of the drain current changes according to the intensity of the irradiation interference light, and the potential change based on the change in the drain current Is read out as a hologram data signal DATA by the drain driver Dd.

Next, another embodiment of the present invention will be described with reference to FIG.
In the hologram imaging element of this embodiment, a light separating / projecting element Oe having a light diffusing film 31 attached to a semi-transmissive reflecting plate 30 is disposed as light separating / projecting means. Other configurations are the same as those in the above embodiment.

  The transflective plate 30 constituting the light separating / projecting element Oe of the present embodiment is made of a thin metal plate and reflects and transmits incident light at a predetermined ratio. A light diffusing film 31 is deposited on one main surface of the transflective plate 30 made of a thin metal plate, and the light diffusing film 31 is disposed so as to face the photosensor array plate Aps, thereby separating light. A projection element Oe is installed. In this case, the light diffusion film 31 is provided in order to prevent regular reflection of light that is transmitted through the photosensor array plate Aps and reflected by the transflective plate 30. In order to prevent regular reflection of light incident on the transflective plate 30, fine irregularities are simply formed on the surface of the transflective plate 30 facing the photo sensor array plate Aps by surface treatment such as embossing. Just be fine.

  According to the present embodiment, the light R emitted from the semiconductor laser light source 5 and transmitted through the photosensor array plate Aps enters the transflective plate 30 via the diffusion film 31, and a predetermined proportion of the light is reflected. Then, another predetermined ratio of light is transmitted and projected onto the kokeshi doll f of the imaging object.

  The reflected light R 2 is diffused through the diffusion film 31 and projected as a reference light to the corresponding photo sensor 2. On the other hand, the light R1 transmitted through the semi-transmissive reflector 30 and projected onto the kokeshi doll f of the object to be imaged is reflected on the surface thereof to become object light, and enters the semi-transmissive reflector 30 again and is transmitted therethrough. Since the object light transmitted through the transflective reflector 30 is diffused light reflected by the non-smooth surface of the object to be imaged, both the reference light and object light projected on the photosensor 2 are diffusely reflected. The lights have substantially the same intensity, and the interference action of both lights proceeds smoothly.

  Thereafter, interference light composed of reference light and object light, both of which are diffusely reflected light, is projected onto the corresponding photosensor 2, and similarly to the above embodiment, a hologram representing the light intensity distribution of interference light, that is, interference fringes. The data signal DATA is read by the drain driver Dd.

  As described above, according to the present embodiment, as the light separating and projecting means, the light separating layer in which the light scattering layer is laminated on the transflective reflector 30 that reflects a part of the incident light and transmits the other part. Since the projection element Oe is arranged, the structure of the hologram imaging element is further simplified.

The present invention is not limited to the specific embodiment described above.
For example, after separating incident light into reflected light and transmitted light, projecting the reflected light onto a photosensor as reference light, projecting the reflected light onto an object to be imaged, and reflecting it as object light 2, so long as it can be projected onto the same photosensor that has projected the reference light. Therefore, in the embodiment shown in FIG. Also good.

  Further, the light source light is not limited to laser light, and quasi-monochromatic light such as LED (Light-Emitting Diode) light can also be suitably used.

It is explanatory drawing which shows the whole concept of the hologram imaging element as one Embodiment of this invention. It is a principal part expanded sectional view which shows the detailed structure of the said hologram imaging element. It is a schematic block diagram which shows the whole structure of the said hologram imaging element. It is a principal part expanded sectional view which shows the hologram imaging element as other embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Glass substrate 2 Photosensor 3 Reflective polarizing plate 4 λ / 2 phase difference plate 5 Light source (semiconductor laser)
6 Condensing Lens 7 Pinhole 8 Collimator Lens 20 Semiconductor Layer 22 Source Electrode 23 Drain Electrode 26 Top Gate Electrode 28 Bottom Gate Electrode 29 Protective Insulating Film 30 Transflective Reflector 31 Diffusion Layer Aps Photosensor Array Plate Osp Optical Laminate Oe Light Separate projection element Dd Drain driver Cd controller

Claims (4)

On a substantially transparent insulating substrate, a semiconductor layer that generates electron-hole pairs by incidence of light, a source electrode and a drain electrode that are electrically connected to both ends of the semiconductor layer, and at least the semiconductor layer A photo in which a plurality of photosensors including gate electrodes arranged opposite to each other via an insulating layer with respect to the central portion are arranged in a predetermined arrangement with a substantially transparent insulating layer interposed therebetween to form a sensor array surface A sensor array;
A light source unit that emits coherent light, causes the emitted light to be incident on the insulating substrate of the photosensor array, transmits between the photosensors, and emits the light from the sensor array surface;
Reference light that is disposed opposite to the sensor array surface of the photosensor array and reflects part of the light emitted from the sensor array surface of the photosensor array toward the sensor array surface, and of the emitted light Is separated into irradiation light that transmits the other part of the image and irradiates the imaging target, and interference fringes are formed on the sensor array surface by the object light reflected by the imaging target of the irradiation light and the reference light. A light separating projection means to be formed;
A hologram imaging element comprising:   The light separating and projecting means includes a reflective polarizing plate having a transmission axis and a reflection axis orthogonal to each other, and the polarization direction of the object light transmitted through the reflective polarizing plate and projected and reflected by the imaging object. 2. The hologram imaging according to claim 1, wherein an optical element that is linearly polarized along a transmission axis is laminated, and the reflective polarizing plate is disposed to face a sensor array surface of the photosensor array. element.   The light separating and projecting unit is formed by laminating a diffuse reflection layer on a transflective plate that reflects a part of incident light and transmits another part, and the diffuse reflection layer is formed on the sensor array surface of the photosensor array. The hologram imaging element according to claim 1, wherein the hologram imaging element is disposed so as to face the surface. 4. The hologram imaging element according to claim 1, wherein the photosensor is formed in a double gate type thin film transistor structure in which the gate electrodes are arranged one by one with the semiconductor layer interposed therebetween. .

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