JPH05100244A - Spatial optical modulating element - Google Patents

Abstract

PURPOSE:To easily adjust the size of an input pattern by forming a photodetecting element by using a photoconductive layer and measuring the current which flows to the photodetecting element. CONSTITUTION:A transparent conductive electrode 102 is formed on a transparent insulating substrate 101, a photoconductive layer 103 is deposited thereupon, and a picture element electrode 104 for photodetecting and processing input light and a position detection electrode 105 which forms a photodetecting element for detecting the size of the input image are further laminated. Spacers 106 are used to sandwich a liquid crystal layer 109 with a transparent insulating substrate 108 where a transparent electrode 107 is formed. Here, oriented films 110 and 111 are formed on the liquid crystal layer 109. When a pattern is inputted to this element, a voltage is applied to the position detection electrode 105 to measures currents flowing to the individual electrodes.

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 in an optical arithmetic unit for pattern recognition or image processing.

[0002]

2. Description of the Related Art A spatial light modulator is an important element for realizing optical information processing such as optical logic operation and optical neurocomputing. In particular, the optical writing type spatial light modulator is different from the electric writing type in which line-sequential driving is performed, and information is written in two-dimensional parallel light so that the time required for writing can be shortened and high-speed operation is expected. it can.
Such a photo-writing type spatial light modulator generally has a structure in which a photoconductive layer and a modulation part such as liquid crystal are combined, and the modulation part is formed by inputting light into the photoconductive layer. It switches and modulates the intensity of the output light.

The optical computer is expected to exceed the conventional von Neumann type computer because it can realize high-speed computation by large-scale parallel processing by utilizing the parallelism of light. Among them, an optical neuro-computer that constructs a neural network with light is used to make intelligent information that humans have, such as judgment, recognition, association, and learning, because of the consistency with the parallelism of the neural network. Recently, it has been rapidly attracting attention as a means for realizing processing. The key device for constructing these optical computers is the spatial light modulator as described above. As an optical neurocomputer using a spatial light modulator, an example of performing character recognition by an associative function in a system as shown in Fig. 8 has been reported {Reference: Takimoto et al. IEICE Technical Committee Sample LAV-91. -10 (1991) 49.}. The optical neuron element used in this system is a spatial light modulator having optical summation and optical threshold processing functions.

Further, when obtaining the Fourier transform of an image,
Conventional computers require a considerable amount of computation time,
Optically, it can be easily obtained by using a lens. However, in order to measure the power spectrum of the Fourier transform pattern obtained optically, it is converted into an electric signal using a TV camera or a commercially available dedicated photodetector (provided with concentric circles and radial electrodes). Is being done.

[0005]

In a character recognition device using a computer, characters are cut out when a character is input. Similarly, the character recognition device shown in FIG. In the case of a computing system, the input pattern must be input at a fixed position and a fixed size. However, in practical use, for example, when performing character recognition,
Characters used in actual documents vary in size and must be aligned character by character. In other words, if you enter a character without adjusting the optical system so that the character will be the specified size or the character will be placed in the specified position, even if it is a perfect character, it will not be recognized correctly. Can not. Therefore, the optical system must be adjusted in order to always measure the character size and input the character so that the size is always constant. Usually, the size of a character is measured by capturing an input pattern using a television camera and electrically processing it. Therefore, there is a problem in that the image data having a large amount of data must be processed, the measurement takes time, and the meaning of high-speed calculation using the optical parallelism becomes meaningless. Further, since the television camera is provided separately from the calculation system, the device becomes large in size and the cost is high, so that it is not practical.

The Fourier transform can be easily executed by using an optical system. When used for character recognition, the size and rotation of characters can be recognized without any problems. Therefore, it is a very effective method in pattern recognition and image processing. However, for the analysis of the power spectrum of the Fourier transform pattern, since there is no element that can be processed in parallel by light, generally, the converted pattern is
However, there is a problem that the overall calculation speed becomes slow because the optical information is converted into an electric signal after all, because it is analyzed using a TV camera and a dedicated photodetector.

The present invention is to solve the above-mentioned conventional problems. In the first invention, the size of the input pattern to the optical operation system is easily adjusted with a simple structure. It is an object of the present invention to provide a spatial light modulation element that can be used.

It is an object of the second and third aspects of the present invention to provide a spatial light modulator capable of optically calculating a Fourier transform pattern.

[0009]

The spatial light modulator of the first invention has a structure in which a photoconductive layer and a portion where the amount of light transmission changes according to an electric field are sandwiched by conductive electrodes. To form a light receiving element and measure a current flowing through the light receiving element.

The spatial light modulator of the second invention has a structure in which a photoconductive layer sandwiched between opposing conductive electrodes is electrically connected to a portion where the amount of transmitted light changes by an electric field. In the device, concentric and radial electrode patterns are formed on one of the conductive electrodes sandwiching the photoconductive layer.

A third aspect of the present invention is a spatial light modulation element in which a photoconductive layer sandwiched by conductive electrodes and a light emitting layer which emits light by applying an electric field are electrically connected to each other. Concentric and radial electrode patterns are formed on one of the electrodes.

[0012]

In the spatial light modulation element for performing calculation, the light receiving element is formed just outside the area where the image or character pattern is input. Then, a voltage is applied to this light receiving element,
Adjusting the position of the input image while checking the magnitude of the flowing current,
In addition, the size of the input image can be easily kept constant by adjusting the optical system for forming the input image on the spatial light modulator. For example, consider the case of entering characters. The letters are usually written in black on a white background. Therefore,
When the image of the character pattern overlaps the light receiving element, the current decreases. That is, if the size of the input character pattern is determined so that the current flowing through the light receiving element is about to decrease,
Input to the spatial light modulator is always possible with a constant size. In addition, since the light receiving element is manufactured using part of the photoconductive layer of the spatial light modulator, it does not incur extra cost, and the current value to be measured is only a few points. The size of the input pattern can be adjusted faster than with a simpler system.

Since the power spectrum of the Fourier transform pattern obtained optically is point symmetric,
By making the light receiving region of the photoconductive layer of the spatial light modulator element concentric and radial, the frequency distribution and the angle distribution can be input in parallel at the same time, and the non-linear processed signal by the modulator or the light emitting element can be output optically. Therefore, the Fourier transform pattern can be processed at a higher speed than a television camera that can only output electricity or a conventional commercially available photodetector.
In addition, when such a Fourier-transformed pattern is used for input such as character recognition, it is possible to correctly recognize even if the size of the stored character is different or it is rotated. ..

[0014]

Embodiments of the present invention will be described with reference to the drawings.

FIG. 1 shows an embodiment of the spatial modulator of the first invention. (A) is a sectional view thereof, and (b) is a plan view of a substrate on which a photoconductive layer is formed.

The device is constructed such that a transparent conductive electrode (eg ITO or SnO _x ) 102 is formed on a transparent insulating substrate 101 (eg glass substrate), and a photoconductive layer 10 is formed thereon.
3 is deposited, and a pixel electrode 104 for receiving and calculating input light and a position detection electrode 105 forming a light receiving element for detecting the size of an input image are stacked. A liquid crystal layer 109 is sandwiched by a transparent insulating substrate 108 on which a transparent conductive electrode 107 is formed using a spacer 106. However, alignment films 110 and 111 are formed on the liquid crystal layer 109.

When a pattern is input to this element, a voltage is applied to the position detection electrode 105 and the current flowing through each electrode is measured. The reason why the pair of electrodes are arranged in four directions as shown in FIG. 1 is that the input pattern accurately aligns the photoconductive layer 103. The method of aligning the input image using these electrodes will be described below.

First, the current flowing through the electrode 105 when the ground of the input image is completely input into the position detection electrode 105 is used as a reference current. For example, consider the case where a character written in black on a white background is used as an input image. In this case, if a character overlaps the position detection electrode 105, the current flowing through the electrode becomes smaller than the reference current. Therefore, the reference current flows through the outer electrode,
So that a smaller current flows through the inner electrode,
If you satisfy the upper and lower or left and right electrode pairs at the same time,
The input image can be contained between the outer and inner electrodes. This state is shown in FIG. Also, if the characters are arranged in an orderly manner, the reference current should flow to the inner electrode and a smaller current to the outer electrode so that it can be input if the upper and lower or left and right electrode pairs are satisfied at the same time. It is possible to set the ruled line around the character or the state where the character is overlapped with the outer electrode. That is, the input image can be input to the spatial light modulator within the area surrounded by the inner electrodes. This state is shown in FIG. The shape of the position detection electrode 105 depends on the shape of the input image, and may be, for example, a fan-shaped curve.

In FIG. 1B, the pixel electrode 104 of the spatial light modulator is formed inside the position detection electrode 105, but as shown in FIG. 2, the pixel electrode 104 is formed separately and the same input is made by using a lens array. Images may be input to the position detection electrode 105 and the pixel electrode 104 to perform the alignment.

Next, the operation of the spatial light modulator will be described. Before light irradiation, the dark resistance of the photoconductive layer 103 is larger than the resistance of the liquid crystal layer 109. Therefore, when a voltage is applied to the element from the outside, most of the voltage is applied to the photoconductive layer 103. Therefore, the transmittance of the liquid crystal layer 109 does not change. However, when the photoconductive layer 103 is irradiated with light, the resistance of the photoconductive layer 103 decreases. Therefore, the voltage applied to the liquid crystal layer 109 increases, and the transmittance of the liquid crystal layer 109 changes. The readout method of the output light is the pixel electrode 104 when the transmission type readout is performed.
A transparent conductive electrode such as ITO is used, or the pixel electrode 104 is removed. At this time, although not shown in the figure, polarizing plates are arranged on both sides of the device. Further, in the case of reading by the reflection type, the reading light is incident from the transparent insulating substrate 108 side through the polarizing plate separately from the input light, and the reflected light is observed. When using the reflective type, Ag, A
A metal thin film having a high reflectance such as l, Cr, Ni, or Mo is used for the pixel electrode 104, or the pixel electrode 104 is removed and an alignment film 110 and a photoconductive layer 103 are alternately filled with a dielectric material having a different refractive index. Forming a dielectric mirror laminated on the substrate. Pixel electrode
Although 104 is a quadrangle in FIG. 1, it may have any shape in accordance with the shape of incident light. Further, when the input image is treated as spatially continuous information, the pixel electrode 104 may be omitted.

A thin film made of a material having a bandgap sufficiently smaller than that of the photoconductive layer 103 is inserted between the photoconductive layer 103 and the pixel electrode 104 as a light absorbing layer for preventing reflection of incident light in order to increase resolution. Is also good.

Here, as the liquid crystal material of the liquid crystal layer 109,
Examples thereof include nematic liquid crystals, ferroelectric liquid crystals of chiral smectic C phase, and dispersion type liquid crystals in which liquid crystals are dispersed in a polymer. When the dispersed liquid crystal is used, it is easy to manufacture, and since the alignment films 110 and 111 and the polarizing plate are unnecessary, the structure is simple. Further, when the ferroelectric liquid crystal is used, the thickness of the liquid crystal layer is reduced, so that the capacitance can be increased, and high-speed response is possible, and the memory function can be realized. Further, since the ferroelectric liquid crystal has a steep threshold characteristic, it is an optimum material for optical threshold processing.

The material used for the photoconductive layer 103 operates as a dielectric in the dark and loses the characteristics of the dielectric due to photoconductivity during light irradiation. Specifically, CdS, Cd
Te, CdSe, ZnS, ZnSe, GaAs, Ga
Compound semiconductors such as N, GaP, GaAlAs and InP,
Amorphous semiconductors such as Se, SeTe, AsSe, Si, G
e, Si _1-x C _x , Si _1-x Ge _x , Ge _1-x C _x (0 <x <1) polycrystalline or amorphous semiconductor, and (1) phthalocyanine pigment (abbreviated as Pc) For example, metal-free Pc, XPc (X =
Cu, Ni, Co, TiO, Mg, Si (OH) _2, etc.), AlClPcCl, TiOClPcCl, InC
lPcCl, InClPc, InBrPcBr, etc.
(2) Azo dyes such as monoazo dyes and disazo dyes,
(3) Penylene-based pigments such as penylene acid anhydrides and penylene acid imides, (4) indigoid dyes, (5) quinacridone pigments, (6) polycyclic quinones such as anthraquinones and pyrenequinones, (7) cyanine dyes, (8)
There are organic semiconductors such as xanthene dyes, (9) charge transfer complexes such as PVK / TNF, (10) eutectic complexes formed from pyrylium salt dyes and polycarbonate resins, and (11) azurenium salt compounds.

Amorphous Si, Ge, Si _1-x C _x ,
_{Si 1-x Ge x, Ge} 1-x C x ( hereinafter, a-Si, a-G
e, a-Si _1-x C _x , a-Si _1-x Ge _x , a-Ge _1-x
When using the abbreviated) as C _x in the photoconductive layer 103, may be included hydrogen or halogen, may include oxygen or nitrogen because of the increased and resistivity to reduce the dielectric constant. To control the resistivity, B, Al, and G which are p-type impurities
elements such as a, or P, As, S which are n-type impurities
An element such as b may be added. By stacking the amorphous materials to which impurities are added in this manner, p / n, p / i, i / n,
A dielectric such as p / i / n may be formed and a depletion layer may be formed in the photoconductive layer 103 to control the dielectric constant and dark resistance or the operating voltage polarity.

In addition to such an amorphous material, two or more kinds of the above materials may be laminated to form a heterojunction to form a depletion layer in the photoconductive layer 103.

FIG. 4 shows an embodiment of the spatial light modulator of the second invention. FIG. 4A is a sectional view and FIG. 4B is a plan view of a substrate on which a photoconductive layer is formed.

As for the structure of the device, a photoconductive layer 303 is deposited on a transparent insulating substrate 302 on which a transparent conductive electrode 301 is formed, as in the spatial light modulator of FIG. 1, and further concentric electrodes 304 and radial electrodes 305. And a transparent insulating substrate 307 on which a transparent conductive electrode 306 is formed, and a liquid crystal layer 309 in which a liquid crystal is sealed using a spacer 308. However, the liquid crystal layer 309 uses the alignment films 310 and 311 that have been subjected to the alignment treatment.

Since this device is basically used in a reflection type, the concentric electrodes 304, the radial electrodes 305 and the alignment film 310 are used.
A dielectric mirror in which dielectrics having different refractive indexes are alternately laminated, or Ag, Al, Cr, N
A metal thin film with high reflectance such as i or Mo is used as the concentric electrode 30.
4 and radial electrodes 305. The materials forming the photoconductive layer 303 and the liquid crystal layer 309 are the same as above.

An embodiment of the spatial light modulator of the third invention is shown in FIG. FIG. 5A is a sectional view of the device, and FIG. 5B is a plan view excluding the light emitting layer. A photoconductive layer 403 is laminated on a transparent insulating substrate 402 on which a transparent conductive electrode 401 is formed. Further, concentric electrodes 404 and radial electrodes 405 are formed,
A light emitting layer 406 and a transparent conductive electrode 407 are sequentially laminated. As the light emitting layer 406, a thin film electroluminescent (EL) element whose area can be easily increased is preferable. As the material of the EL element, for example, ZnS or E added with Mn or Tb, F is used.
CaS, Pr or Ce, Eu or P with u added
An inorganic EL material such as SrS to which r and Ce are added, an organic EL material such as 8-quinolinol Al complex, Al oxine complex, and perylene can be used. Organic EL materials emit light at a DC voltage, while inorganic EL materials are driven by an AC voltage.
Therefore, when an inorganic EL material is used, the photoconductive layer 403
Does not provide rectifying property only in one direction like a pn junction, but instead of pinp, nipn, pnp, pnpn, pi
It is necessary to have a rectifying property in both directions such as npin. Specific examples will be described below.

Example 1 A spatial light modulator having a structure as shown in the sectional view of FIG. 1A was produced. The manufacturing method of this element will be described below.

IT having a thickness of 0.05 to 0.5 μm is formed on the glass substrate 101.
O was deposited by sputtering to form the transparent conductive electrode 102. Next, a photoconductive layer 103 was formed by laminating an a-Si: H film having a p / i / n diode structure with a thickness of 0.5 to 2 μm by plasma CVD. Subsequently, a pixel electrode 104 array and a position detection electrode 105 made of aluminum and having a thickness of 0.03 to 0.3 μm were formed. Next, a polyimide alignment film 110 that had been subjected to a rubbing treatment was laminated. A ferroelectric liquid crystal layer 1 having a thickness of 0.5 to 3 μm is formed between this and a glass substrate 108 on which a transparent conductive electrode pattern 107 of ITO and a polyimide alignment film 111 are laminated.
09 was enclosed and a spatial light modulator was produced.

A character pattern was input to the spatial light modulator while measuring the current flowing through the position detection electrode 105 while applying a reverse bias of 0.1 to 10 V to the position detection electrode 105. However, the character pattern is a character written in black on a white background paper, which was irradiated with white light, and the reflected light was used as the input of the spatial light modulator. As a result, it was possible to align the character pattern with the spatial light modulator in about 1/10 of the time required when using a conventional TV camera.

Example 2 A spatial light modulator having a structure as shown in the sectional view of FIG. 4A was produced. The manufacturing method thereof will be described below.

IT of 0.05 to 0.5 μm thickness on the glass substrate 302
O was deposited by a sputtering method to form a transparent conductive electrode 301. Next, a photoconductive layer 303 was formed by laminating an a-Si: H film having a p / i / n diode structure with a thickness of 0.5 to 2 μm by plasma CVD. Then, a concentric electrode 304 and a radial electrode 3 made of aluminum with a thickness of 0.03 to 0.3 μm.
Formed 05. Next, a rubbing-treated polyimide alignment film 310 was laminated. A ferroelectric liquid crystal layer 309 having a thickness of 0.5 to 3 μm was enclosed between this and a glass substrate 307 on which a transparent conductive electrode pattern 306 of ITO and a polyimide alignment film 311 were laminated to manufacture a spatial light modulator.

Using this spatial light modulator 501, an apparatus for optically recognizing characters as shown in FIG. 6 was constructed. This device places an input image 503 perpendicular to the optical axis of the lens 502,
A spatial light modulator 501 is arranged on the side opposite to the input image 503 with the lens 502 interposed therebetween. Input image 503 and spatial light modulator 501
The distance from the lens 502 is equal to the focal length (f) of the lens 502. When the input image 503 is irradiated with the laser beam 504, the Fourier transform image of the input image 503 is input to the photoconductive layer 503 of the spatial light modulator 501. The output light 507 obtained by passing the read light 505 through the polarization beam splitter 506 is modulated according to the amount of light entering the concentric electrodes 304 and the radial electrodes 305. When a ferroelectric liquid crystal is used as in this example, only the electrode where a certain amount of light or more is incident is output light.
It is possible to obtain the result of performing the threshold processing such that 507 is obtained. The output light 507 is multiplexed and expanded by the lens array 508, further passes through the memory mask 509,
The light enters the spatial light modulation element 510 in which the pixel electrodes 104 are arranged in the same shape as the lens array 508. This spatial light modulator 510 is
In the spatial light modulator shown in FIG. 1, the position detection electrode 105
Is removed, and the result of performing threshold processing on the amount of light incident on the pixel electrode 104 is optically output. The memory mask 509 weights the transmittance of multiple images of concentric and radial light. In the present embodiment, as an example, the input image 503 uses the letters of the alphabet (A to Z) and the orthogonal learning method. What was produced by was used.
Therefore, the spatial light modulator 510 outputs the result of performing character recognition on the input image 503. Also, the recognition result
511 is obtained by using the polarization beam splitter 512 as in the case of the spatial light modulator 501.

It has been confirmed that the apparatus can correctly recognize the input characters 503 that are reduced or enlarged or rotated in the input image 503.

Example 3 As an example of the third invention, a spatial light modulator as shown in FIG. 5 was produced. The manufacturing method of this element will be described below.

IT of 0.05 to 0.5 μm thickness on the glass substrate 402
O was deposited by a sputtering method to form a transparent conductive electrode 401. Next, by a plasma CVD method, an a-Si _x C _1-x : H film (0 <x <having a thickness of 0.5 to 2 μm and a p / i / n / p structure is formed.
0.4) was laminated to form a photoconductive layer 403. continue,
A concentric electrode 404 and a radial electrode 405 made of a metal such as Au, Pt, or Pd having a thickness of 0.03 to 0.3 μm were formed. These metals are for forming an ohmic junction in the p layer. Next, 100-500 Å prepared by sputtering method
0.1 to 1 Mn-doped ZnS sandwiched by insulating thin films of SiN _x , SiO _x , AlO _x , TaO _x, etc.
Then, the light emitting layer 406 was formed with a thickness of μm. Electron beam evaporation, MOCVD, or sputtering was used to form the ZnS film.
Further, as a transparent conductive electrode 407 facing each of the concentric electrode 404 and the radial electrode 405, an IT of 0.05 to 0.3 μm is used.
O was formed to produce a spatial light modulator. When the transparent conductive electrode 407 is formed in a smaller area than the concentric electrodes 404 and the radial electrode 405 facing each other, the current density in the light emitting layer 406 can be increased, and the brightness can be increased, which is advantageous. It was target. Further, in FIG. 5, the transparent conductive electrode 407 has a square shape and a circular shape, but if the shape is within the area of the corresponding electrodes 404 and 405, the same operation is performed with any shape.

An apparatus for optically recognizing characters as shown in FIG. 7 was constructed using the spatial light modulator 601. This device used the same elements as in FIG. Lens 60
The input image 603 was placed perpendicularly to the optical axis of 2, and the spatial light modulator 601 was arranged on the side opposite to the input image 603 with the lens 602 interposed therebetween.
The distances of the input image 603 and the spatial light modulator 601 from the lens 602 are both equal to the focal length (f) of the lens 602.
When the input image 603 is irradiated with the laser beam 604, the Fourier transform image of the input image 603 is input to the photoconductive layer 403 of the spatial light modulator 601. The output light 605 emitted from the light emitting layer 406 is modulated according to the amount of light entering the concentric electrodes 404 and the radial electrodes 405. The output light 605 is multiply developed by the lens array 606, further passes through the memory mask 607, and enters the spatial light modulation element 608 in which the pixel electrodes 104 are arranged in the same shape as the lens array 606. Further, the recognition result 609 is obtained by making the reading light 610 incident on the polarization beam splitter 611.

It has been confirmed that this apparatus can correctly recognize the input image 603 even when inputting or reducing or enlarging the rotated input image 603.

Further, since this device uses the spatial light modulation element using the light emitting layer 406, it does not need read light and can be simplified as compared with FIG. However, this modulator does not have a memory function like a ferroelectric liquid crystal.

[0042]

According to the first invention, a spatial light modulator capable of adjusting the size of an input image at high speed and easily can be obtained. According to the second and third inventions, the Fourier transform pattern can be easily obtained. It is possible to obtain a spatial light modulator that can perform optical calculation processing.

[Brief description of drawings]

FIG. 1A is a sectional view of a spatial light modulator according to an embodiment of the present invention, and FIG. 1B is a plan view of the same.

FIG. 2 is a plan view of a spatial light modulator according to another embodiment of the present invention.

FIG. 3 is a diagram showing a state of an input image in one embodiment of the spatial light modulator of the present invention.

FIG. 4A is a sectional view of a spatial light modulator according to an embodiment of the present invention, and FIG.

FIG. 5A is a sectional view of a spatial light modulator according to an embodiment of the present invention, and FIG.

FIG. 6 is a sectional view showing an example of the configuration of a character recognition device using a spatial light modulator according to an embodiment of the present invention.

FIG. 7 is a cross-sectional view showing another example of the configuration of the character recognition device using the spatial light modulator in one embodiment of the present invention.

FIG. 8 is a sectional view showing a configuration of a conventional optical associative memory.

[Explanation of symbols]

 101, 108 Transparent Insulating Substrate 102, 107 Transparent Conductive Electrode 103 Photoconductive Layer 104 Pixel Electrode 105 Position Detection Electrode 106 Spacer 109 Liquid Crystal Layer 110, 111 Alignment Film 301, 306 Transparent Conductive Electrode 302, 307 Transparent Insulating Substrate 303 Photoconductive layer 304 Concentric electrode 305 Radial electrode 308 Spacer 309 Liquid crystal layer 310, 311 Alignment film 401 Transparent conductive electrode 402, 407 Transparent insulating substrate 403 Photoconductive layer 404 Concentric electrode 405 Radial electrode 406 Light emitting layer

Claims (7)

[Claims] 1. In a spatial light modulator having a structure in which a photoconductive layer and a liquid crystal layer are sandwiched by conductive electrodes facing each other, a light receiving element is formed using the photoconductive layer, and a current flowing through the light receiving element is measured. A spatial light modulation element characterized by the above. 2. A spatial light modulator having a structure in which a photoconductive layer sandwiched by opposing conductive electrodes and a liquid crystal layer are electrically connected to each other, wherein one of the conductive electrodes sandwiching the photoconductive layer has a concentric shape. And a radial electrode pattern, which is a spatial light modulator. 3. A spatial light modulator in which a photoconductive layer sandwiched between opposing conductive electrodes and a light emitting layer which emits light when an electric field is applied are electrically connected to each other. On the other hand, a spatial light modulation element characterized in that concentric and radial electrode patterns are formed. 4. The spatial light modulator according to claim 3, wherein the areas of the conductive electrodes sandwiching the light emitting layer are different. 5. The spatial light modulator according to claim 1, wherein the photoconductive layer has a rectifying property. 6. The spatial light modulator according to claim 1, wherein the liquid crystal layer is made of a ferroelectric liquid crystal. 7. The spatial light modulator according to claim 1, wherein the photoconductive layer is formed of an amorphous semiconductor containing at least one element selected from the elements of carbon, silicon and germanium. ..