JPH06332003A - Spatial optical modulating element - Google Patents

Abstract

PURPOSE:To provide the spatial optical modulation element which does not generate unnecessary interference fringes and unnecessary diffraction patterns. CONSTITUTION:The part to serve as a passage for reading out light of the spatial optical modulation element SLM is provided with laminating a random phase shift layer RPSL for randomly changing the phase of the reading out light in the cross sectional direction of the passage in tight contact with other constituting members. As a result, the unnecessary interference fringes by the light reflected from the front and rear surfaces of the respective constituting members of the spatial optical modulation element SLM does not appear in the image read out and reproduced from the spatial optical modulation element SLM. The unnecessary diffraction patterns of the random phase shift layer RPSL do not appear either.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spatial light modulator used as a component in an image pickup device, a display device, a signal processing device in an optical computer, a hologram recording / reproducing device and the like.

[0002]

2. Description of the Related Art A video signal obtained by picking up an optical image of a subject with an image pickup device is easy to edit, trim, and other image signal processing, and a reversible recording member capable of erasing a recorded signal is used. Although it has the feature that recording and reproduction can be performed easily by using it, the image pickup device that has been generally used conventionally for generating a video signal has a photoelectric conversion unit in the image pickup element by an image pickup lens. The formed optical image of the subject is converted into electrical image information corresponding to the optical image of the subject by the photoelectric conversion unit of the image sensor, and the electrical image information is converted into a serial video signal on the time axis. It is well known that various image pickup tubes and various solid-state image pickup devices have been conventionally used as the above-mentioned image pickup device in the configuration of an image pickup apparatus in which the image pickup device can be output.

It is well known that, in recent years, new demands for television systems such as so-called EDTV and HDTV have been proposed in response to a growing demand for reproduced images of high image quality and high resolution. As described above, in order to obtain a reproduced image with high image quality and high resolution, an image pickup device capable of generating an image signal capable of reproducing the reproduced image with high resolution is required. In the conventional image pickup apparatus using an image pickup device such as a pickup tube or a two-dimensional solid-state image pickup device, however, a video signal capable of reproducing a high-resolution reproduced image due to the existence of various problems that the image pickup device has. Could not be generated well,
The applicant company has proposed an imaging device using a light-light conversion element (spatial light modulation element) as a constituent element as an imaging apparatus capable of solving the above-mentioned problems, and also configured a spatial light modulation element. When used as an element, a display device that can display a high-definition display image, or a signal processing device that uses a spatial light modulator as a constituent element so that it can also be used in an optical computer, or a spatial light A hologram recording device or the like has been proposed in which a modulator is used as a constituent element.

[0004]

By the way, as a spatial light modulation element for processing image information with high resolution, since each of the laminated constituent members is constructed to be extremely thin, a reading light is used. When coherent light is used as the above, there is a problem that unnecessary interference fringes appear due to the reflected light on the front and back surfaces of the above-mentioned constituent member. In order to solve the above problems, the spatial light modulator,
I tried adding a phase plate (random phase shifter) that was configured as an individual component, but since the above two are separate components, the phase plate (random phase shifter) was added to the read image. It was not possible to adopt such a solution because of the appearance of unwanted diffraction patterns by the shifter. Therefore, a solution that does not cause the above-mentioned problems was sought.

[0005]

According to the present invention, a portion serving as a passage of read-out light in a spatial light modulation element constituted by at least a photoconductive layer member and a light modulation material layer member between two transparent electrodes. Provided is a spatial light modulator in which a random phase shift layer that randomly changes the phase of read light in the transverse direction of a passage is laminated in close contact with other constituent members.

[0006]

When the optical image of the subject is formed on the photoconductive layer member of the spatial light modulator with the driving voltage being supplied between the transparent electrodes by the imaging lens, an electric field corresponding to the optical image of the subject is generated. It is added to the light modulation material layer member in the spatial light modulation element described above. The read light that has entered the light modulation material layer member in the spatial light modulation element from the light source of the read light has its light state changed by the electric field corresponding to the optical image of the subject while reciprocating through the light modulation material layer member. Light is emitted from the spatial light modulator as a light, but a random phase shift layer that randomly changes the phase of the reading light in the cross-sectional direction of the passage is provided in the portion that serves as the passage of the reading light. Since they are provided in close contact, unnecessary interference fringes do not appear in the read image due to the reflected light from the front and back surfaces of each of the above-mentioned constituent members, and the unnecessary diffraction pattern of the random phase shifter layer. Does not appear.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The specific contents of the spatial light modulator of the present invention will be described in detail below with reference to the accompanying drawings. 1 to 5 are longitudinal side views showing a schematic configuration of an embodiment of the spatial light modulation element of the present invention, and FIG. 6 is a random type used in one embodiment of the spatial light modulation element of the present invention. Phase
It is a perspective view for explaining an example of composition of a shifter layer. In the spatial light modulator SLM shown in FIGS. 1 to 5, BP1,
BP2 is a transparent substrate (eg glass substrate), and Et
1, Et2 are transparent electrodes (for example, electrodes of ITO film),
The electrode Et1 is transparent to the writing light WL, and the electrode Et2 is transparent to the reading light RL. PCL is a photoconductive layer member, DML is a dielectric mirror that reflects the readout light RL, and PML is a light modulation material layer member that is composed of a light modulation material that can change the light state according to the intensity distribution of the electric field.
(For example, a liquid crystal layer, a light modulating material such as a lithium niobate single crystal, or a light modulating material layer member configured by using another light modulating material), ALL1 and ALL2 are light modulating material layer members PML. The alignment film used when liquid crystal is used, RPSL, is a random phase phase filter formed in a portion of the spatial light modulator SLM through which read light passes.
It is a shifter layer. Further, E is a power source connected between the transparent electrodes Et1 and Et2 during operation. In the figure, WL
Is writing light for writing an optical image as a charge image on the reflective spatial light modulator SLM, and RL is read light used for reading the charge image formed on the reflective spatial light modulator SLM.

The spatial light modulator SLM shown in FIGS. 1 and 2.
The random phase shifter layer RPSL in is provided between the transparent substrate BP2 and the transparent electrode Et2,
The random phase shifter layer RPSL in the spatial light modulator SLM shown in FIG. 3 is formed on the transparent electrode Et2 itself provided on the transparent substrate BP2, and the spatial light modulation shown in FIG. The random phase shifter layer RPSL in the element SLM is a spatial light modulation element S configured by using liquid crystal as a light modulation material layer member.
The random film shifter layer RPSL in the spatial light modulator SLM shown in FIG. 4B is formed by using liquid crystal as a light modulator material layer member. The random film shifter layer RPSL of the spatial light modulator SLM shown in FIG. 5 is formed on the alignment film ALL1 itself of the spatial light modulator SLM. Is configured. And the above-mentioned random phase shifter layer RPSL
Is configured such that the phase of the reading light can be randomly changed in the cross-sectional direction of the passage in the portion of the spatial light modulator SLM that serves as the passage of the reading light.

In the spatial light modulator SLM shown in FIG. 1, the transparent substrate BP2 and the transparent electrode Et2 on the incident side of the reading light.
The random phase shifter layer RPSL provided between and can be formed on the transparent substrate BP2 on the incident side of the reading light, for example, as follows. That is,
First, a silicon nitride (Si3N4) film 1 is adhered and formed on the transparent substrate BP2 on the read light side by, for example, a plasma CVD method, and then a photolithography technique is applied on the silicon nitride film 1 to make it several microns. ~ A mask having a predetermined pattern is sequentially formed a plurality of times at a pitch of several tens of microns. Then, every time the mask of each type is formed on the silicon nitride film 1, the holes having different predetermined depths are formed by dry etching, thereby crossing the passage of the read light. A silicon nitride (Si3N4) film 1 having two-dimensionally distributed holes 1a, 1a, 1a, ... Of which the depth is randomly changed in the plane direction is formed (FIG. 6).
reference). The area of the individual holes 1a, 1a, 1a ...
It is much larger than the pixel size. The hole 1 described above
a, 1a, 1a ... with 4 kinds of depth are prepared,
Using four masks as described above, the depths are randomly changed in the cross-sectional direction of the passage of the readout light so that the above-mentioned four kinds of holes having different depths are randomly arranged on a plane. By forming the silicon nitride (Si3N4) film 1 in which the formed holes 1a, 1a, 1a ... Are two-dimensionally distributed, a random phase shifter layer RPSL having sufficient performance in practical use can be formed. .

Next, as shown in FIG. 6, the silicon nitride (Si3N) deposited and formed on the transparent substrate BP2 on the incident side of the reading light.
4) A solution of a silicon dioxide-based substance was applied to the uneven surface side where the holes in the film 1 in which the depths were randomly changed were two-dimensionally distributed, by the SOG method (Spin On Glass).
By spin coating with s), the layer 2 is formed so that the uneven surface side becomes a flat surface, and
The phase shifter layer RPSL is configured, and the random phase shifter layer RPSL configured as described above is a portion of the holes 1a, 1a, 1a ... In which the depth randomly changes as described above. Each time, the phase of the read light passing through that portion is changed randomly, but the random phase shifter layer RPSL described above is used.
Must be configured so that the phase difference between the read lights is at most 2π radians. A transparent electrode Et2 is attached on the above-mentioned random phase shifter layer RPSL, and further, an alignment film ALL2, a liquid crystal layer PML, an alignment film ALL1, a dielectric mirror DML, a photoelectric layer member PCL, a transparent electrode Et1, a transparent substrate BP1. Thus, the spatial light modulator SLM is configured as a state in which is sequentially stacked.

Next, the random phase shifter layer RPSL in the spatial light modulator SLM shown in FIG. 2 is a transparent material layer 3 adhered and formed on the transparent substrate BP2 and has a small area having different refractive indexes. 3a, 3a, 3a
, Are arranged randomly in the surface direction. The area of each of the small areas 3a, 3a, 3a ... Is sufficiently larger than the size of the pixel. In addition, the individual minute area portions 3 described above
As a, 3a, 3a ..., four kinds of materials having different refractive indexes are prepared, and the above-mentioned four kinds of minute area portions having different refractive indexes are randomly arranged on a plane. Random phase with sufficient performance
The shifter layer RPSL can be configured. The random phase shifter layer RPSL needs to be configured such that the phase difference between the read lights is within 2π radians at the maximum. Since the surface of the random phase shifter layer RPSL is flat, the transparent electrode Et2 is attached to the surface, and the alignment film ALL2, the liquid crystal layer PML, the alignment film ALL1, the dielectric mirror DML, the photoelectric layer. The spatial light modulator SLM is configured in a state where the member PCL, the transparent electrode Et1, and the transparent substrate BP1 are sequentially laminated.

The random phase shifter layer RPSL in the spatial light modulator SLM shown in FIG.
With the transparent electrode Et2 itself attached and formed on P2,
In order to form the phase shifter layer RPSL, the transparent electrode Et2 has a configuration in which minute areas 4a, 4a, 4a ... Having different refractive indexes are randomly arranged in the plane direction. ing. The area of each of the small areas 4a, 4a, 4a ...
It is much larger than the pixel size. It should be noted that as the individual small area portions 4a, 4a, 4a ..., four kinds of states having different refractive indexes are prepared, and the above-mentioned four kinds of minute area portions 4a, 4a, 4a having different refractive indexes are prepared. The random phase shifter layer RPSL having sufficient performance in practical use if the ... Are randomly arranged on the plane.
Can be configured. And the random phase
The shifter layer RPSL needs to be configured so that the phase difference between the read lights is within 2π radians at the maximum. Since the random phase shifter layer RPSL composed of the transparent electrode Et2 itself has a flat surface, the alignment film ALL2, the liquid crystal layer PML, the alignment film ALL1, the dielectric mirror DML, the photoelectric layer is formed on the surface. The spatial light modulator SLM is configured in a state where the member PCL, the transparent electrode Et1, and the transparent substrate BP1 are sequentially laminated.

Next, the spatial light modulator S shown in FIG.
The random phase shifter layer RPSL in LM is
The alignment film ALL2 itself in the spatial light modulator SLM configured by using liquid crystal as the light modulation material layer member is configured so that the alignment film ALL2 functions as the random phase shifter layer RPSL. In order to achieve the above, as the alignment film ALL2, there is used a configuration in which minute areas 5a, 5a, 5a ... Having different refractive indexes are randomly arranged in the plane direction. Then, the individual minute area portions 5a, 5a,
The area of 5a ... Is sufficiently larger than the size of the pixel. As the individual small area portions 5a, 5a, 5a ..., four kinds of states having different refractive indexes are prepared, and the above-mentioned four kinds of minute area portions 5a, 5 having different refractive indexes are prepared.
When a, 5a ... Are randomly arranged on a plane, a random phase
The shifter layer RPSL can be configured. The random phase shifter layer RPSL needs to be configured such that the phase difference between the read lights is within 2π radians at the maximum. Since the surface of the random phase shifter layer RPSL composed of the alignment film ALL2 itself is flat, the liquid crystal layer PML, the alignment film ALL1, the dielectric mirror DML, the photoelectric layer member PCL, and the transparent layer are formed on the surface of the random phase shifter layer RPSL. The spatial light modulator SLM is configured in a state where the electrode Et1 and the transparent substrate BP1 are sequentially stacked.

Next, the spatial light modulator S shown in FIG. 4B.
The random phase shifter layer RPSL in LM is
The liquid crystal is used as the light modulation material layer member in the alignment film ALL1 itself in the spatial light modulation element SLM, and the alignment film ALL1 functions as a random phase shifter layer RPSL. In order to achieve the above, as the alignment film ALL1, there is used a configuration in which minute areas 6a, 6a, 6a ... Having different refractive indexes are randomly arranged in the plane direction. Then, the individual small area portions 6a, 6a,
The area of 6a is sufficiently larger than the size of the pixel. It should be noted that as the individual minute area portions 6a, 6a, 6a ..., four kinds of states having different refractive indexes are prepared, and the above-mentioned four kinds of minute area portions 6a, 6 having different refractive indexes are prepared.
When a, 6a ... Are randomly arranged on a plane, a random phase
The shifter layer RPSL can be configured. The random phase shifter layer RPSL needs to be configured such that the phase difference between the read lights is within 2π radians at the maximum. Since the surface of the random phase shifter layer RPSL composed of the alignment film ALL1 itself is flat, the dielectric mirror DML, the photoelectric layer member PCL, the transparent electrode Et are formed on the surface.
1, the spatial light modulator SLM is configured in a state where the transparent substrate BP1 is sequentially laminated.

The random phase shifter layer RPSL in the spatial light modulator SLM shown in FIG.
P2 itself is a structure in which small area portions 7a, 7a, 7a ... Having different refractive indexes are randomly arranged in the plane direction as the transparent substrate BP2 so as to form the random phase shifter layer RPSL. Embodiments are used. Then, the individual minute area portions 7a,
The area of 7a, 7a ... Is sufficiently larger than the size of the pixel. In addition, the individual minute area portions 7a, 7a, 7
As a ..., four kinds of materials having different refractive indexes are prepared, and the four kinds of minute area portions 7 having different refractive indexes are provided.
By randomly arranging a, 7a, 7a ... On a plane, a random phase shifter layer RPSL having practically sufficient performance can be constructed. The random phase shifter layer RPSL needs to be configured such that the phase difference between the read lights is within 2π radians at the maximum. The above-mentioned transparent substrate BP2 itself constitutes the random phase shifter layer RPSL, and the surface of the random phase shifter layer RPSL is flat. Therefore, the transparent electrode Et2, the alignment film ALL2, and the liquid crystal layer are formed on the transparent substrate BP2. PML, alignment film ALL1, dielectric mirror DML, photoelectric layer member PCL,
The spatial light modulator SLM is configured in a state where the transparent electrode Et1 and the transparent substrate BP1 are sequentially stacked.

In the spatial light modulator SLM of the present invention having the above-mentioned structure, the power source E is connected to the electrodes Et1 and Et2 of the spatial light modulator SLM so that an electric field is applied between both ends of the photoconductive layer member PCL, and the reflection type spatial light is produced. When the writing light WL is incident from the electrode Et1 side of the modulation element SLM, the writing light WL incident on the reflective spatial light modulation element SLM passes through the electrode Et1 and reaches the photoconductive layer member PCL. Since the electric resistance value of the photoconductive layer member PCL changes corresponding to the intensity distribution of the writing light WL that has reached it, the intensity of the writing light WL is provided at both ends of the light modulation material layer member PML in the spatial light modulator SLM. A field strength distribution corresponding to the distribution is produced.

As described above, the electric field intensity distribution corresponding to the intensity distribution of the writing light WL is generated at both ends of the light modulation material layer member PML, and the reading light RL having a constant intensity from the electrode Et2 side in the spatial light modulation element SLM. When the light is incident, the read light RL passes through the light modulation material layer member PML, is reflected by the dielectric mirror DML, passes through the light modulation material layer member PML again, and is emitted from the electrode Et2 in the spatial light modulation element SLM. Therefore, if the light modulation material layer member PML in the spatial light modulator SLM operates in, for example, a birefringence mode, the read light RL corresponds to the charge image and the read light ( Since the readout light RLr in the state where the polarization plane of (linearly polarized light) is changed is emitted from the electrode Et2 side of the spatial light modulation element SLM, the spatial light modulation element SLM described above is The reading light RLr emitted from the side of the electrode Et2 that changes the state of the reading light changes corresponding to the intensity distribution of the writing light WL. However, in the spatial light modulator SLM of the present invention, the reading light RL is read. Since the random phase shift layer RPSL having a function of randomly changing the phase of the reading light with respect to the cross-sectional direction of the passage of the reading light is provided as one of the constituent members of the position where the light passes, The readout light emitted from the spatial light modulator SLM is the random phase shift layer RP described above.
With SL, the phase is randomly changed for each region having a small area in the cross-sectional direction of the reading light.

[0018]

As is clear from the above description, the spatial light modulation element of the present invention comprises the photoconductive layer member of the spatial light modulation element in which the driving voltage is supplied between the transparent electrodes. When an optical image of the subject is formed by the imaging lens, an electric field corresponding to the optical image of the subject is applied to the light modulation material layer member in the spatial light modulation element, and the spatial light modulation element is read from the light source of the reading light. The read light that has entered the light modulation material layer member at is emitted from the spatial light modulation element as light whose light state is changed by the electric field corresponding to the optical image of the subject while reciprocating through the light modulation material layer member. But,
Since a random phase shift layer that randomly changes the phase of the reading light in the cross-sectional direction of the passage is provided in the portion which becomes the passage of the reading light in close contact with other constituent members. In addition, in the image read and reproduced from the spatial light modulator of the present invention, unnecessary interference fringes do not appear due to the reflected light on the front and back surfaces of each component of the spatial light modulator, and the random phase shifter is used. No unnecessary diffraction pattern of the layer appears,
According to the present invention, the above-mentioned problems can be solved well.

[Brief description of drawings]

FIG. 1 is a vertical sectional side view showing a schematic configuration of an embodiment of a spatial light modulator of the invention.

FIG. 2 is a vertical sectional side view showing a schematic configuration of an embodiment of the spatial light modulator of the invention.

FIG. 3 is a vertical sectional side view showing a schematic configuration of an embodiment of the spatial light modulator of the present invention.

FIG. 4 is a vertical sectional side view showing a schematic configuration of an embodiment of the spatial light modulation element of the present invention.

FIG. 5 is a vertical sectional side view showing a schematic configuration of an embodiment of the spatial light modulator of the invention.

FIG. 6 is a perspective view for explaining a configuration example of a random phase shifter layer used in an embodiment of the spatial light modulator of the present invention.

[Explanation of symbols]

SLM ... Spatial light modulator, BP1, BP2 ... Transparent substrate, E
t1, Et2 ... Transparent electrode, PCL ... Photoconductive layer member, DML ...
Dielectric mirror, PML ... Light modulation material layer member, ALL1, A
LL2 ... Alignment film, RPSL ... Random phase shifter layer formed in the portion of the spatial light modulator SLM through which the reading light passes,

Front page continuation (72) Masato Furuya, 3-12 Moriya-cho, Kanagawa-ku, Yokohama, Japan Victor Company of Japan, Ltd. (72) Minae Terai 3--12, Moriya-cho, Kanagawa-ku, Yokohama Japan Victor Co., Ltd. (72) Inventor Tetsuhiro Yamazaki 3-12 Moriya-cho, Kanagawa-ku, Yokohama-shi, Kanagawa Japan Victor Co., Ltd.

Claims (1)

[Claims] 1. A phase of read-out light is provided in a portion which becomes a passage of read-out light in a spatial light modulator including at least a photoconductive layer member and a light-modulating material layer member between two transparent electrodes. A spatial light modulation element in which a random phase shift layer that randomly changes in the cross-sectional direction of a passage is laminated in close contact with other constituent members.