JPH0728085A - Optical address type spatial optical modulation device - Google Patents

Abstract

PURPOSE:To provide an optical address type spatial optical modulation device capable of effectively cutting the zero order light component of light Fourier transformation and effectively taking signal light components into a light address part even if the result of this transformation is inputted to the eight address part.. CONSTITUTION:A photoconductive layer 13 and a liquid crystal layer 16 are laminated between transparent electrodes 12 and 18. A voltage is impressed to the photoconductive layer 13 and the liquid crystal layer 16 by the transparent electrode 12. The photoconductive layer 13 receives writing light and changes its resistance according to the light intensity thereof, thereby changing the optical characteristics of the liquid crystal layer 16. The liquid crystal layer 16 receives reading light and modulates the light. A partial region 12a of the transparent electrode 12 is etched and the voltage is not impressed to the corresponding regions 13a, 16a of the photoconductive layer 13 and the liquid crystal layer 16. Then, the region 13a does not change the optical characteristics of the region 16a even if the writing light is made incident thereon.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical address type spatial light modulator, and more particularly to an optical address type spatial light modulator which is particularly suitable for a spatial light modulator in the subsequent stage of a congruential conversion correlator.

[0002]

2. Description of the Related Art Conventionally, as a photo-address type spatial light modulator, a pair of glass face plates on which a transparent conductive film is formed as shown in FIG. A structure having a liquid crystal layer sandwiched therebetween is known.

FIG. 13 shows a Joint Transform Correlation (JTC) using such a spatial light modulator.
Shown in. The congruential conversion type correlator is configured by using two spatial light modulators (first and second spatial light modulators). The first pattern P _i and the second pattern P _r are simultaneously written in the first spatial light modulator, and these are read out and spatially Fourier transformed by the first Fourier transform lens to obtain a joint Fourier transform pattern. To form. Since the second spatial light modulator is arranged such that its photoconductive layer is located on the Fourier transform plane (focal plane) of the first Fourier transform lens, the intensity pattern of the joint Fourier transform pattern (that is, The power spectra of the first and second patterns) are written in the second spatial light modulator. This is read and spatially Fourier transformed again to form a correlation signal pattern light corresponding to the correlation between the first pattern and the second pattern. The detector detects the light intensity and outputs it as a correlation signal.

[0004]

Here, since the optical Fourier transform result is input as a writing pattern to the optical address section of the second spatial light modulator, the 0th-order optical component thereof becomes noise. There is. For this reason, as shown in FIG. 14, a mask for blocking the 0th-order light is arranged immediately before the address side glass face plate of the second spatial light modulator.

However, in such an arrangement method, the 0th-order light-shielding mask is displaced from the Fourier transform surface by at least the thickness of the glass face plate, so that the 0th-order light component cannot be effectively cut and necessary information is combined. There is a possibility that even the signal light component of the Fourier transform pattern may be cut.

Therefore, an object of the present invention is to effectively cut the 0th-order light component when the optical Fourier transform result is used as a writing pattern and is input, and
It is an object of the present invention to provide an optical address type spatial light modulator which can effectively take in a signal light component.

[0007]

In order to achieve the above object, in the photo-address type spatial light modulator of the present invention, as shown in FIG. It was decided to eliminate the sensitivity of the part where the light component enters.

That is, the photo-addressable spatial light modulator of the present invention comprises a photo-conductive layer as a photo-addressing part and a liquid crystal layer as a photo-modulating part, the photo-conductive layer receiving writing light and receiving the writing light. In the optical address type spatial light modulator in which the optical characteristic of the liquid crystal layer is changed according to the optical characteristic, the liquid crystal layer receives the read light and modulates the light according to the optical characteristic, the optical address section writes It is characterized by having an insensitive part to light. here,
It is preferable that the insensitive portion is provided substantially at the center of the optical address portion. Further, the shape and area of the insensitive portion may be determined in consideration of the frequency component to be cut.

It is preferable to provide an input / output separation section for separating the optical address section and the optical modulation section from each other. Here, the input / output separation unit includes a mirror layer and / or a light shielding layer.

The optical address type spatial light modulator of the present invention comprises:
Furthermore, it is preferable to provide a pair of transparent electrodes for applying a voltage to the optical address section and the optical modulation section, which are provided so as to sandwich the optical address section and the optical modulation section. When the input / output separation unit is provided between the optical address unit and the optical modulation unit, the pair of transparent electrodes,
It is provided so as to sandwich the optical address section, the input / output separation section, and the optical modulation section.

[0011]

Function: A voltage is applied to the photoconductive layer, which is an optical address section, and the liquid crystal layer, which is an optical modulation section. The photoconductive layer receives the writing light and changes the optical characteristics (eg, refractive index) of the liquid crystal layer in response to the writing light. The liquid crystal layer receives the read light and modulates it according to its optical properties. here,
An insensitive portion is formed on a part of the optical address portion. The insensitive portion does not change the optical characteristics of the corresponding portion of the liquid crystal layer even when the writing light is incident. Therefore, the read light that has entered the liquid crystal layer is not modulated according to the light intensity of the write light that has entered the insensitive portion. In other words, according to the spatial light modulator of the present invention, the read light can be modulated according to only the write light that has entered the area of the optical address portion excluding the insensitive portion.

Here, when an input / output separation section is provided between the optical address section and the optical modulation section, the input / output separation section effectively makes the read light incident on the optical address section. The optical address section and the optical modulation section are separated.

Further, when a pair of transparent electrodes is provided, these apply a voltage to the photoconductive layer which is an optical address section and the liquid crystal layer which is an optical modulation section.

When the spatial light modulator of the present invention is provided in the subsequent stage of the Fourier transform lens and the Fourier transform pattern is made incident on the optical address portion as the writing light, the 0th order light component of the Fourier transform pattern is the optical axis of the Fourier transform lens. Image as the center. Therefore, it is preferable to provide an insensitive portion in the approximate center of the optical address portion and arrange the spatial light modulator with respect to the Fourier transform lens so that the insensitive portion is located on the optical axis of the Fourier transform lens. In this case,
In the Fourier transform pattern, the 0th-order light component is incident on the insensitive portion, and the signal light component is incident on the optical address portion other than the insensitive portion. As a result, the reading light that has entered the liquid crystal layer can be modulated by only the signal light component of the Fourier transform pattern.

As described above, according to the present invention, since the insensitive portion is directly formed on the photoconductive layer which is the optical address portion of the spatial light modulator, it is formed on the Fourier transform surface regardless of the thickness of the glass face plate. It is possible to effectively cut off the 0th-order light component and also effectively take in the signal light component.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is applied to a photo-address type spatial light modulating device which employs a parallel alignment type nematic liquid crystal layer in a light modulating portion will be described below with reference to the drawings.

First, a first embodiment of the present invention will be described with reference to FIGS.
Will be described in detail with reference to. As shown in FIG. 2, in this parallel alignment type nematic liquid crystal spatial light modulator 1, a parallel alignment nematic liquid crystal layer 16 as a light modulator is provided between a pair of alignment layers 15 and 17. On the side of the alignment layer 15 opposite to the liquid crystal layer 16, the mirror layer 14 and the light shielding layer 1 are provided.
4 ', a photoconductive layer 13 as an optical address portion, a transparent conductive film 12, and an address side glass substrate 11 are provided in this order. A transparent conductive film 18 and a read side glass substrate 19 are provided on the side of the alignment layer 17 opposite to the nematic liquid crystal layer 16. The rubbing directions of the alignment layers 15 and 17 are the same, and the liquid crystal molecules of the nematic liquid crystal layer 16 are arranged in parallel with the substrates 11 and 19 without being twisted as shown in FIG. (Parallel orientation or homogeneous orientation). An alternating drive voltage (amplitude V) is applied from the drive power supply 2 between the pair of conductive films 12 and 18. The light shielding layer 14 'may or may not be provided as needed.

Here, as shown in FIGS. 2 and 3, the substantially central portion of the transparent conductive film 12 is etched and removed in a circular shape (hereinafter, this etching region is referred to as "etching region 12a", The region of the transparent conductive film 12 left unetched is referred to as "electrode region 12b". Therefore, the photoconductive layer 13 corresponding to the etching region 12a is
No voltage is applied to the region 13a of FIG. 3 and the region 16a of the liquid crystal layer 16. (In other words, the region 13b of the photoconductive layer 13 and the region 16 of the liquid crystal layer 16 corresponding to the electrode region 12b.
The voltage is applied only to b. )

The photoconductive layer 13 is preferably made of hydrogenated amorphous silicon (a-Si: H),
Amorphous silicon (a-Si), CdS, Bi ₁₂ S
It may be made of iO ₂₀ , an organic photoconductor (PVK), or the like. The transparent conductive films 12 and 18 are made of, for example, ITO (Indium).
-Tin-Oxide). The mirror layer 14 is made of, for example, a dielectric mirror. The light shielding layer 14 ′ is, for example,
It consists of CdTe. The alignment layers 15 and 17 may be formed by coating the mirror layer 14 and the transparent conductive film 18 with PVA or polyimide and then rubbing them, or Si.
It may be produced by oblique vapor deposition of O, formation of an LB film, or the like.

The operation of the spatial light modulator 1 having such a configuration will be described below. When writing light is incident on the photoconductive layer 13 through the address side glass substrate 11, the resistance at that portion decreases according to the writing light intensity, and a voltage according to the writing light intensity is applied to the liquid crystal layer 16. The liquid crystal molecules move so as to rise with respect to the conductive films 12 and 18 according to the voltage. As a result, the refractive index of the light polarized in the length direction of the liquid crystal molecules (the light having the plane of polarization indicated by the arrow a in FIG. 4) changes. Therefore, when coherent read light polarized in the length direction of the liquid crystal molecules is incident on the liquid crystal layer 16 via the read side glass substrate 19, the light undergoes phase modulation according to the change in the refractive index. The read light is reflected by the mirror layer 14, undergoes phase modulation again in the liquid crystal layer 16, and then is emitted through the glass substrate 19.

Details of the parallel alignment type nematic liquid crystal spatial light modulator 1 are described in the specification of Japanese Patent Application No. 4-203505 already filed by the present applicant.

In the spatial light modulator 1 of this embodiment,
No voltage is applied to the region 13a of the photoconductive layer 13. Therefore, even if the writing light enters the region 13a through the etching region 12a, the refractive index of the region 16a of the liquid crystal layer 16 corresponding to the region 13a does not change. Therefore, the reading light is not modulated by the writing light applied to the area 13a. That is,
The area 13a functions as an insensitive portion to the writing light. (In addition, the region 16a functions as a non-modulation portion for the reading light.) In other words, according to the spatial light modulator 1, the reading is performed only by the writing light irradiated to the region 13b corresponding to the electrode region 12b. Dashi light is modulated.

When the spatial light modulator 1 for performing such an operation is arranged, for example, at the subsequent stage of the Fourier transform lens and the Fourier transform pattern is inputted as the writing light, as shown in FIG. The spatial light modulator 1 is arranged so that the center of the circular etching region 12a is substantially located on 3X so that the etching region 12a is irradiated with the 0th-order light component. In view of the above points, it is preferable that the circular etching region 12a be formed in the substantially central portion of the transparent conductive film 12 as shown in FIG.

On the other hand, the radius r of the circular etching region 12a
With regard to the above, an appropriate value can be obtained by the following formula 1 from the relationship between the Fourier transform lens 3 to be combined and the maximum spatial frequency to be cut.

## EQU1 ## where r is the wavelength of the writing light [mm], f is the focal length of the Fourier transform lens 3 [mm], and u is the maximum spatial frequency to be cut [cycles / mm] ]. Specifically, when it is desired to cut the 0th-order light component of the spatial frequency u ₁ or less,
The high-pass filter may be constructed by etching the circular region 12a having the radius r ₁ (= λ · f · u ₁ ) as shown in (A).

When it is desired to cut the 0th-order light component having the spatial frequency u ₂ or more, the radius r ₂ as shown in FIG.
So that the circular electrode region 12b of (= λ · f · u ₂ ) remains,
The low pass filter may be formed by etching all regions 12a of the transparent conductive film 12 except the circular region 12b.

When it is desired to cut the 0th-order light component having a spatial frequency of u ₃ or more and u ₄ or less, the radius r as shown in FIG. 6C is r ₃ (= λ · f · u ₃ ) or more r ₄ (= λ · f · u ₄ )
A bandpass filter may be formed by etching the following concentric region 12a.

An application example in which the spatial light modulator 1 of the present embodiment is applied to a joint conversion correlator will be described below with reference to FIG.

This congruential conversion type correlator 100 comprises a first parallel alignment type nematic liquid crystal spatial light modulator 1A for simultaneously recording a first pattern and a second pattern, a drive power source 2A thereof, and a subsequent stage. a first Fourier transform lens 22 disposed on the spatial light modulator with light Y ₁ read 1
A half mirror 21 for guiding the reading light Y ₁ which is guided to A and modulated by the spatial light modulator 1A to the first Fourier transform lens 22, and the first Fourier transform lens 2
Second parallel alignment type nematic liquid crystal spatial light modulator 1B for recording the intensity distribution of the congruent Fourier transform pattern obtained by 2, the driving power supply 2B, and the second Fourier transform lens arranged in the subsequent stage. 24 and a half mirror 23 for guiding the reading light Y ₂ to the spatial light modulator 1B and for guiding the reading light Y ₂ modulated by the spatial light modulator 1B to the second Fourier transform lens 24. , And a light intensity detector 25 for detecting the light intensity of the correlation signal light obtained by the second Fourier transform lens 24.

Here, as the first spatial light modulator 1A, an ordinary parallel alignment type nematic liquid crystal spatial light modulator in which the etching region 12a is not formed is used. Further, as the second spatial light modulator 1B, the parallel alignment type nematic liquid crystal spatial light modulator 1 in which the etching region 12a of the present embodiment is formed is used. Further, as described in detail with reference to FIG. 5, the spatial light modulator 1B is arranged so that the center of the circular etching region 12a is substantially located on the optical axis 22X of the Fourier transform lens 22. The radius r of the circular etching region 12a is, for example, when the spatial frequency u or less is desired to be cut, the mathematical formula r = λ · f ·
given by u. Here, f is the focal length of the Fourier transform lens 22, and λ is the wavelength of the reading light Y ₁ .

The operation of the congruential conversion type correlator 100 will be described below.

The photoconductive layer 13 of the spatial light modulation device 1A, simultaneously enters first pattern P _i and the second pattern P _r through the address side glass substrate 11, and the pattern P _i in the liquid crystal layer 16 Record P _r (specifically its intensity distribution). The reading light (coherent light) Y ₁ in a linearly polarized state polarized in the length direction of the liquid crystal molecules of the liquid crystal layer 16 is applied to the reading side glass substrate 19 of the spatial light modulator 1A via the half mirror 21. In the liquid crystal layer 16, the pattern P _i
・ Reading light Y emitted after undergoing phase modulation according to P _r
1 is spatially Fourier-transformed by the first Fourier transform lens 22 after passing through the half mirror 21, and the concatenated Fourier transform pattern (hereinafter, referred to as “first Fourier transform”) of the patterns P _i and P _r is formed on the Fourier transform surface. "Pattern") P
_{Image f} . Spatial light modulator 1 on the Fourier transform plane
B photoconductive layer 13 is disposed. Therefore, the first Fourier pattern P _f is incident on the photoconductive layer 13 of the spatial light modulator 1B. More specifically, the 0th-order light component of the spatial frequency u or less of the first Fourier pattern P _f enters the corresponding circular region 13a of the photoconductive layer 13 via the circular etching region 12a. A 0th-order light component higher than the spatial frequency u and a component of 1st-order light or higher (that is, a signal light component) are incident on the remaining region (that is, the region 13b corresponding to the electrode region 12b) other than the circular region 13a. Here, the drive voltage is not applied to the region 16a of the liquid crystal layer 16 corresponding to the circular region 13a. Therefore, even if the 0th-order light component enters the circular region 13a,
The refractive index of the corresponding region 16a of the liquid crystal layer 16 does not change. On the other hand, since the drive voltage is effectively applied to the area other than the area 16a in the liquid crystal layer 16 (that is, the area 16b corresponding to the area 13b), the 0th-order light component and the signal light component higher than the spatial frequency u are generated. The intensity distribution is recorded. That is, the power spectra of the patterns P _i and P _r are recorded in the liquid crystal layer in a form with less noise. The reading light (coherent light) Y ₂ in a linearly polarized state polarized in the length direction of the liquid crystal molecules of the liquid crystal layer 16 is applied to the reading glass substrate 19 of the spatial light modulator 1B via the half mirror 23. This read light Y ₂ undergoes phase modulation by the power spectrum distribution of the patterns P _i and P _{r in} the liquid crystal layer 16 and then exits, passes through the half mirror 23, and is spatially Fourier transformed by the Fourier transform lens 24. Then, the Fourier pattern (hereinafter referred to as the second Fourier pattern) P _f ′ of the power spectra of the patterns P _i and P _r is imaged on the Fourier transform plane. Here, the second Fourier pattern P _f 'is the 0th-order light corresponding to the intensities of the patterns P _i and P _r , and the + first-order light and −, which are arranged in point symmetry with respect to the zero-order light.
It consists of primary light. The image formation positions of the + 1st order light and the −1st order light correspond to the relative positions of the patterns P _i and P _r , and their light intensities are equal to each other and correspond to the correlation of the patterns P _i and P _r . That is, the + 1st order light and the −1st order light are the patterns P _i and P _r.
Is a signal light correlated with. A light intensity detector 25 including, for example, a photodiode is arranged at a position on the Fourier transform surface where the + 1st order light is imaged. Detector 25
Detects the + 1st order light intensity and outputs a correlation signal indicating the correlation between the patterns P _i and P _r . Here, the + 1st-order light is obtained based on the signal light component of the power spectra of the patterns P _i and P _r and the 0th-order light component of the desired spatial frequency. Therefore, the light intensity has a high S / S correlation between the patterns P _i and P _r.
N ratio is shown. That is, this congruential conversion type correlator 10
According to 0, the correlation between the patterns P _i and P _r can be detected with a high S / N ratio.

A second embodiment of the present invention will be described below with reference to FIGS. As shown in FIGS. 8 and 9, in the spatial light modulator 1 ′ of this embodiment, instead of etching the transparent conductive film 12, the photoconductive layer 13 of the transparent conductive film 12 is used.
A reflective or absorption type circular mask 20 is provided on the surface in contact with
a is formed. For example, when the photoconductive layer 13 is composed of hydrogenated amorphous silicon (a-Si: H), after forming a reflective or absorption type mask 20a on the transparent conductive film 12 in advance, a-Si: H light is used. A conductive layer may be formed.

Here, as the material of the reflection type mask,
Metals such as aluminum (Al), chromium (Cr), titanium (Ti) and the like are preferable. As the material of the absorption mask, for example, cadmium tellurium (CdTe),
preferable.

According to the spatial light modulator 1'of this embodiment,
The writing light incident on the circular mask 20a receives the photoconductive layer 1
It does not enter the corresponding region 13a of No. 3. Therefore, the region 16a of the liquid crystal layer 16 corresponding to the region 13a
The index of refraction does not change. That is, the area 13a
Functions as an insensitive portion to the writing light.
(In addition, the region 16a functions as a non-modulation portion for the reading light.) As described above, according to the spatial light modulator 1 ′ of the present embodiment, the writing light intensity incident on the position of the mask 20a is changed. It does not modulate the reading light.
The read light can be modulated according to only the writing light intensity incident on the region 13b of the photoconductive layer 13 excluding the region 13a.

When the spatial light modulator 1'having such a structure is used in combination with a Fourier transform lens, as shown in FIG. 10, the optical axis 3 of the lens 3 is used, as in the first embodiment.
The relative position between the lens and the spatial light modulator 1 ′ is selected so that X penetrates the approximate center of the circular mask 20a. Therefore, as in the first embodiment, the mask 20a is also preferably formed on the surface of the transparent conductive film 12 at a substantially central portion, as in the first embodiment.

The radius r of the circular mask 20a is also given as shown in FIG. 6A, as in the first embodiment.

The shape and size of the mask 20a depend on the spatial frequency of the 0th order light component to be cut, and the etching region 1 shown in FIG. 6B or 6C of the first embodiment.
It is preferable to be the same as 2a.

When the spatial light modulator 1'of the present embodiment is applied to the spatial light modulator 1B of the latter stage of the congruential conversion correlator, it may be the same as the spatial light modulator 1 of the first embodiment. . An example of this application is shown in FIG.

The present invention is not limited to the spatial light modulators of the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention.

For example, although the above-mentioned embodiments relate to the photo-address type spatial light modulator using the parallel alignment type nematic liquid crystal as the light modulator, the present invention is not limited to this.
INDUSTRIAL APPLICABILITY The present invention can be applied to an optically addressed spatial light modulator that uses various liquid crystals as the light modulator. For example, twisted nematic (TN) liquid crystal, surface-stabilized ferroelectric liquid crystal (SSFLC), antiferroelectric liquid crystal (AFLC), field effect birefringence mode (ECB) liquid crystal, super twisted nematic (STN) liquid crystal, etc. It can be applied to all general spatial light modulators using liquid crystals. The spatial light modulator in this case is similar to the parallel alignment type nematic liquid crystal spatial light modulator of the above-mentioned embodiment, and the mirror layer 14 and the light shielding layer 14 '.
Both may be provided, only one of the mirror layer and the light shielding layer may be provided, or both may not be provided.

The application of the spatial light modulator of the present invention is not limited to the one used for writing the joint Fourier transform pattern in the joint transform type correlation processing. It can be widely used in various optical systems using the Fourier transform to write the result of the filtering performed on the Fourier transform plane. According to the spatial light modulator of the present invention, since it is not necessary to separately provide a light-shielding mask between the filter and the spatial light modulator, the filter can be provided closest to the address portion of the spatial light modulator.

[0042]

As is apparent from the above detailed description, in the optical address type spatial light modulator of the present invention, the insensitive portion to the writing light is directly formed in the optical address portion. Therefore, when the optical Fourier transform result is input as the writing pattern, the 0th-order light component is effectively cut by the insensitive portion, and the signal light component is effectively taken in.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view showing the structure of an optically addressed spatial light modulator of the present invention.

FIG. 2 is a schematic cross-sectional view showing the structure of a parallel alignment type nematic liquid crystal spatial light modulator according to the first embodiment of the present invention.

FIG. 3 is a sectional view taken along line III-III in FIG.

FIG. 4 is an explanatory diagram showing a state of alignment of liquid crystals in a parallel alignment nematic liquid crystal layer.

5 is an explanatory side view showing the positional relationship between the spatial light modulator and the Fourier transform lens when the spatial light modulator of FIG. 2 is used in combination with the Fourier transform lens.

FIG. 6A shows an etching region 12a when it is desired to cut a 0th-order light component having a spatial frequency u ₁ or less, FIG.
Sectional view corresponding to, (B), the spatial frequency u ₂ or more 0
The cross-sectional view corresponding to FIG. 3, showing the etching region 12a when it is desired to cut the next light component, (C) is a spatial frequency u
FIG. 4 is a cross-sectional view corresponding to FIG. 3, showing an etching region 12a when it is desired to cut off a 0th-order light component of ₃ or more and u ₄ or less.

7 is an optical system plan view showing a congruential conversion type correlator that employs the spatial light modulator of FIG.

FIG. 8 is a schematic cross-sectional view showing the structure of a parallel alignment nematic liquid crystal spatial light modulator according to a second embodiment of the present invention.

9 is a sectional view taken along line IX-IX in FIG.

FIG. 10 is a side view showing the positional relationship between the spatial light modulator and the Fourier transform lens when the spatial light modulator of FIG. 8 is used in combination with the Fourier transform lens.

11 is an optical system plan view showing a congruential conversion type correlator that employs the spatial light modulator of FIG.

FIG. 12 is a schematic cross-sectional view showing the structure of an optically addressed spatial light modulator.

FIG. 13 is a plan view of an optical system showing a congruential conversion type correlator that employs an optical address type spatial light modulator.

14 is a schematic cross-sectional view showing a state in which a 0th-order shielding mask is arranged in the second photo-address type spatial light modulator of the congruential conversion type correlator shown in FIG.

[Explanation of symbols]

 1, 1 ′ Photo-addressable spatial light modulator 12 Transparent conductive film 12a Etching region 12b Electrode region 13 Photoconductive layer 13a Writing light insensitive portion 16 Liquid crystal layer 16a Read light non-modulation portion 20a Reflective or absorption mask 100 Joint conversion Correlator 22 First Fourier transform lens

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[Procedure amendment]

[Submission date] August 5, 1993

[Procedure Amendment 1]

[Document name to be corrected] Drawing

[Correction target item name] All drawings

[Correction method] Change

[Correction content]

[Figure 3]

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[Figure 1]

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[Figure 6]

[Figure 10]

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[Figure 8]

FIG. 11

[Fig. 12]

[Fig. 13]

FIG. 14

Claims (2)

[Claims] 1. A photoconductive layer as a photo-addressing portion and a liquid crystal layer as a light modulating portion, wherein the photoconductive layer receives writing light and changes the optical characteristics of the liquid crystal layer according to the received writing light. In the optical address type spatial light modulator in which the liquid crystal layer receives the read light and modulates the read light according to the optical characteristics, the optical address section is provided with an insensitive section for writing light. Optical address type spatial light modulator. 2. The optical address type spatial light modulator according to claim 1, wherein the insensitive portion is provided substantially in the center of the optical address portion.