JPH1068968A - Spatial optical modulation element and picture projecting device using the element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the spatial optical modulation element in which the photoconductive layer is reset from a signal takeout side, and the picture projecting device using the elements. SOLUTION: An optical modulating section 100 provided between transparent substrates 101 and 107 is formed by a photoconductive layer 103, a dielectric mirror layer 104 and an optical modulating layer 105. Then, the reflecting wavelength range of the layer 104 is set to the range which passes the light beams having a prescribed sensitivity wavelength among the light beams having sensitivity wavelengths that vary the photoconductivity of the layer 103 included in a signal takeout light beams 200 made incident from the layer 107 of the signal takeout side. Thus, the layer 103 is reset from the signal takeout side.

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 for a projector, a display, and the like, and an image projection apparatus using the same, and more particularly, to a device for miniaturizing an image writing unit and eliminating adjustment.

[0002]

2. Description of the Related Art Conventionally, a spatial light modulator (SLM) has a transparent electrode on a first transparent substrate, a photoconductive layer (hereinafter referred to as a PC layer) whose photoconductivity changes with incident light, a light shielding layer, A dielectric mirror layer (reflection layer), a light modulation layer (for example, a liquid crystal layer),
It is composed of a second transparent electrode or a second transparent substrate having a second transparent electrode, and applies a voltage applied between the first and second transparent electrodes to the light modulation layer via the PC layer. Structure.

In this configuration, since the voltage applied to the light modulation layer changes according to the amount of signal light incident on the PC layer, the change in the amount of light incident on the PC layer is extracted through the light modulation layer. Output light modulated by the signal light is obtained.

By the way, from the first output light modulated by the first signal light continuously incident on the spatial light modulator,
When changing to the second output light modulated by the second signal light, the voltage applied to the light modulation layer by the first signal light is:
To stabilize the voltage applied by the second signal light,
It is necessary to return to the initial value (constant value) once. Therefore, between the incidence of the first signal light and the second signal light, light (reset light) for returning the photoconductivity of the photoconductive layer to the initial value so as to set the applied voltage to the initial value may be incident. It is configured.

[0005]

Incidentally, in such a conventional spatial light modulator, it is necessary to provide a sufficient amount of reset light to the entire surface of the PC layer so that the entire light modulation layer is initialized to the same state. is there. Therefore, in a conventional image projection apparatus using such a spatial light modulator, it is necessary to provide a light source 20 for reset light on the PC layer side of the spatial light modulator 1A as shown in FIG. In order to install the light source 20, it is necessary to install a CRT 6, an LCD, or the like used as a means for writing signal light away from the writing surface of the spatial light modulator 1A.

Here, when the CRT 6, LCD, etc. are set apart from the writing surface of the spatial light modulator 1A, an image formed on the CRT / LCD is placed on the PC layer of the spatial light modulator 1A. An optical system 21 for forming an image is required. Although there is an optical system 21 suitable for downsizing such as a fiber plate, the optical system 21 requires a space for introducing reset light and cannot be used in the conventional example. In addition, complicated operations such as optical adjustments that occur due to the use of the signal light imaging system are required.

As described above, when the reset light is made to enter from the PC layer side, the configuration of the spatial light modulation element on the writing side of the incident image is restricted, and miniaturization and non-adjustment are hindered. There was a problem that it was done.

Accordingly, the present invention has been made to solve such a problem, and provides a spatial light modulator capable of resetting a photoconductive layer from a signal extraction side and an image projection apparatus using the same. The purpose is to do so.

[0009]

According to the present invention, there is provided a photoconductive layer provided between a pair of transparent substrates on a signal input side and a signal extraction side on which transparent electrodes are respectively formed, a dielectric mirror layer,
A spatial light modulating element having a light modulating layer, the light having a sensitivity wavelength that changes the photoconductivity of the photoconductive layer contained in light incident from the transparent substrate on the signal extraction side, a predetermined sensitivity wavelength The reflection wavelength range of the dielectric mirror layer is set so that the light having the following is transmitted through the dielectric mirror layer.

Further, the present invention provides a photoconductive layer, a light shielding layer, a dielectric mirror layer, a light modulating layer, and a photoconductive layer provided between a pair of transparent substrates on a signal input side and a signal extraction side each having a transparent electrode formed thereon. In the spatial light modulation element having, the light having a predetermined sensitivity wavelength among the light having a sensitivity wavelength that changes the photoconductivity of the photoconductive layer included in the light incident from the transparent substrate on the signal extraction side is light having a predetermined sensitivity wavelength. A reflection wavelength range of the dielectric mirror layer and a light shielding wavelength range of the light shielding layer are set so as to transmit through the dielectric mirror layer and the light shielding layer.

Further, the present invention is characterized in that a liquid crystal layer is used as the light modulation layer.

Further, the present invention is characterized in that the transparent electrode and the transparent substrate are transparent to visible light and also transparent to light incident from each of the transparent substrates.

The present invention also provides a spatial light modulator, a writing section provided on the signal input side of the spatial light modulator so that the signal light is incident on the spatial light modulator, and a writing section for extracting the signal light. 5. An image projection apparatus comprising: a light source provided on a signal extraction side of the spatial light modulation element so that signal extraction light is incident on the spatial light modulation element. On the other hand, between the spatial light modulation element and the light source, the photoconductivity of the photoconductive layer changed by the signal light is returned to an initial value before the next signal light is incident. It is characterized in that a conversion means is provided.

Further, in the invention, it is preferable that the initialization means causes the light having a predetermined sensitivity wavelength out of the light having the sensitivity wavelength for changing the photoconductivity of the photoconductive layer to be incident on the spatial light modulation element, and The method is characterized by being configured to initialize a layer.

Further, the present invention is characterized in that the initialization means has initialization signal formation means for forming light of a predetermined sensitivity wavelength for initializing the light modulation layer from the signal extraction light. Is what you do.

Further, in the invention, it is preferable that the initialization means superimposes the light having the predetermined sensitivity wavelength on the signal extraction light and enters the spatial light modulation element.

Further, in the invention, it is preferable that the initialization means forms the light having the predetermined sensitivity wavelength by using a light source different from a light source into which the signal extraction light is incident.

Further, as in the present invention, a photoconductive layer, a dielectric mirror layer, and a light modulation layer are provided between a pair of transparent substrates on a signal input side and a signal extraction side, and a reflection wavelength range of the dielectric mirror is provided. Out of the light having the sensitivity wavelength that changes the photoconductivity of the photoconductive layer included in the light incident from the transparent substrate on the signal extraction side, so as to transmit light having a predetermined sensitivity wavelength. Thus, the photoconductive layer can be reset from the signal extraction side.

A photoconductive layer, a light-shielding layer, a dielectric mirror layer, and a light modulation layer are provided between a pair of transparent substrates on the signal input side and the signal extraction side. The light having a predetermined sensitivity wavelength among the light having the sensitivity wavelength that changes the photoconductivity of the photoconductive layer included in the light incident from the transparent substrate on the signal extraction side is transmitted through the light shielding wavelength range of the light shielding layer. By setting such a range, the photoconductive layer can be reset from the signal extraction side.

A light source for injecting the spatial light modulation element with signal extraction light for extracting the signal light incident on the spatial light modulation element from the writing section is provided on the signal extraction side of the spatial light modulation element. By providing initialization means between the spatial light modulator and the initialization means, by returning the photoconductivity of the photoconductive layer changed by the signal light to the initial value before the next signal light is incident. , So that the next signal light is not affected by the previous signal light.

[0021]

Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a sectional view showing the structure of a spatial light modulator according to a first embodiment of the present invention. In FIG. 1, reference numeral 1 denotes a reflective spatial light modulator, and 101 denotes a signal input side. Reference numeral 107 denotes a second transparent substrate which is a transparent substrate on the signal extraction side.

Here, on the first transparent substrate 101, a transparent electrode 102 which is an ITO film (indium tin oxide film) formed by a sputtering method, and a PC layer 103 formed of hydrogenated amorphous silicon are provided. , SiO ₂ layer and T
Dielectric mirror layer 10 formed by alternately overlapping iO ₂ layers
4 are sequentially stacked, and a transparent electrode 106 which is an ITO film is formed on the second transparent substrate 107.

Further, these two transparent substrates 101, 10
7, a liquid crystal layer 105 is interposed as a light modulation layer whose state changes according to the signal light 202 incident from the first transparent substrate 101. The light modulation section 100 is formed by the PC layer 103, the dielectric mirror layer 104, and the liquid crystal layer 105 formed in order from the first transparent substrate 101.

The signal extraction light 200 for extracting the signal light 202 is incident from the second transparent substrate 107 side and then reflected by the dielectric mirror 104. At this time, the first transparent substrate 101 The light is modulated by the liquid crystal layer 105 which changes in accordance with the signal light 202 incident on the PC layer 103 from the light, and is output as output light 201.

The spatial light modulator 1 having such a configuration is
Is manufactured as follows.

First, an ITO film (indium tin oxide film) is formed as a transparent electrode 102 on the first transparent substrate 101 by a sputtering method. Next, the first transparent substrate 102 is set in a low-pressure plasma device, and about 2
00 introducing a mixed gas of SiH ₄ / H ₂ into the apparatus while heated to ° C., the substrate 1 to excite the mixed plasma of SiH ₄ / H ₂ by the high frequency power to this after the low-pressure plasma apparatus
01 to form a hydrogenated amorphous silicon film on PC
The layer 103 is formed. After that, the PC layer 10
The dielectric mirror layer 104 is formed as a reflective layer by alternately stacking 27 SiO ₂ layers and TiO ₂ layers on 3.

Next, the transparent substrate 1 is placed on the second transparent substrate 107.
01, an ITO film to be a transparent electrode 106 is formed by a sputtering method.
The liquid crystal layer 105 is sandwiched between the transparent substrates 107 to manufacture the spatial light modulator 1.

FIG. 2 shows the spectral sensitivity of the PC layer 103 (hydrogenated amorphous silicon) to light incidence.
FIG. 3 shows the spectral characteristics of the reflectance of the dielectric mirror layer 104. As can be seen from FIGS. 2 and 3,
The reflection wavelength range of the dielectric mirror 104 does not include a predetermined sensitivity wavelength among the sensitivity wavelengths at which the photoconductivity of the PC layer 103 changes.

By setting the reflection wavelength range so as not to include the predetermined sensitivity wavelength, the light having the predetermined sensitivity wavelength included in the signal extraction light 200 passes through the dielectric mirror 104. Become a PC
The layer 103 changes so that the PC layer 103 can be controlled (reset) by light from the signal extraction side.

Next, a spatial light modulator according to a second embodiment of the present invention will be described.

FIG. 4 is a sectional view showing the structure of the spatial light modulator according to the second embodiment, in which a glass substrate is used as the first transparent substrate 101 in the same manner as in the first embodiment. It is. In the figure, 1 'is a reflective spatial light modulator, 108 is a light-shielding layer made of an amorphous silicon germanium film, and the light-shielding wavelength range of this light-shielding layer 108 is a range not including a predetermined sensitivity wavelength of the PC layer 103. I have. Note that 100 ′ is the PC layer 103, the light shielding layer 10
8, a light modulation unit having a dielectric mirror layer 104 and a liquid crystal layer 105.

By setting the light blocking wavelength range of the light blocking layer 108 so as not to include the predetermined sensitivity wavelength of the PC layer 103, the light of the PC layer 103 is included in the light transmitted through the dielectric mirror 104. Light having sensitivity is included, so that the PC layer 103 can be controlled (reset) by light from the signal extraction side.

In the fabrication of the spatial light modulator according to this embodiment, an ITO film (indium tin oxide film) is first formed as a transparent electrode 102 on a first transparent substrate 101 by a sputtering method, and then a high frequency Hydrogenated amorphous silicon is formed by a plasma method. Then, SiH
_An amorphous silicon germanium film is formed with a mixed gas obtained by adding GeH ₄ in addition to the mixed gas of ₄ / H ₂ , and the light-shielding layer 108 is formed. Furthermore, a dielectric mirror layer 104 stacked 27 layers alternately Sio ₂ layer and a TiO ₂ layer on the light-shielding layer 108.

Next, the transparent electrode 1 is formed on the second transparent substrate 107.
In the step 06, an ITO film is formed, and the liquid crystal forming the liquid crystal layer 105 is sandwiched between the first transparent substrate 101 and the second transparent substrate 107 to manufacture the spatial light modulator 1 '.

Next, a description will be given of a video projection apparatus according to a third embodiment of the present invention using the spatial light modulator having the above-described configuration.

FIG. 5 is a diagram showing a configuration of an image projection apparatus according to the present embodiment using the spatial light modulator 1 according to the first embodiment. The case where a signal light is written to the element 1 using a CRT 6 and a fiber plate as an optical system 7 for image formation is shown.

In FIG. 1, reference numeral 2 denotes a light source provided on the signal extraction side of the spatial light modulator 1 and using a metal halide lamp 2b with a condenser mirror 2a. The signal extraction light 200 from the light source 2 is a reflection mirror. After being reflected at 11, only the S-polarized light is reflected by the polarization beam splitter 3 and enters the spatial light modulator 1. The light incident on the spatial light modulator 1 is transmitted to a CR, which is a writing unit provided on the signal input side of the spatial light modulator 1.
The liquid crystal layer corresponding to the signal light incident from T6 (see FIGS. 1 and 4)
), The degree of polarization is modulated and emitted.

Further, the modulated light is separated into transmitted light and reflected light by the polarization beam splitter 3, and only the transmitted light passes through the projection lens 4 as output light 201, and is thereafter projected on the screen 5. The output corresponding to the signal light from the CRT 6 is displayed.

On the other hand, reference numeral 10 denotes a rotary filter as initialization means provided between the light source 2 and the reflection mirror 11, and the rotary filter 10 outputs a signal output light 200 from the light source 2.
For example, the filter is realized by forming a multilayer film that reflects infrared light on a rotary filter so as to remove a wavelength at which the PC layer (see FIG. 1) of the spatial light modulator 1 has sensitivity. . In addition, 10A is a rotation axis of the rotary filter 10.

As shown in FIG. 6, a portion of the rotary filter 10 having no filtering function is formed, for example, by partially cutting the rotary filter 10 into a fan shape. The notch 10a is provided between the light source 2 and the reflection mirror 11 during the same synchronization as the rewriting synchronization of the signal light, that is, during the time when the first signal light enters and the next signal light enters. It rotates at the timing when it passes on the optical path formed between them.

Here, by providing the rotary filter 10 having the notch 10a as initialization signal forming means for forming light of a predetermined sensitivity wavelength for initializing such a light modulation layer from signal extraction light, Normally, this rotary filter 10
While the infrared light of the signal extraction light 200 is shielded, the notch 10a of the rotary filter 10 passes on the optical path between the first signal light and the subsequent second signal light, so that the PC Infrared light having sensitivity to the layer (see FIG. 1) passes through the dielectric mirror (see FIG. 1) and is irradiated on the PC layer.

The rotary filter 10 is provided and the infrared light, which is the reset light, is formed from the signal extraction light 200, and the spatial light is interposed between the first signal light and the subsequent second signal light. Take-out side (output side) of modulation element 1
Irradiates the PC layer with a reset light, which is infrared light having sensitivity, to form a PC formed by the first signal light.
The state of the layer can be reset, so that the second signal light is not affected.

Next, an image projection apparatus according to a fourth embodiment will be described.

FIG. 7 is a diagram showing a configuration of an image projection apparatus according to the present embodiment. This image projection apparatus includes a spatial light modulator 1, a light source 2, a polarizing beam splitter 3, a writing CRT 6, a writing optical system. The apparatus comprises a fiber plate 7, a projection lens 4, and a screen 5, while a rotating reflector 12 is provided in place of the rotating filter 10 as initialization means. In addition, 12A is a rotation axis of the rotary reflection plate 12.

As shown in FIG. 8, the rotary reflecting plate 12 has a so-called cold mirror portion 12a for reflecting visible light and passing infrared light, and a reflective mirror for reflecting infrared light by depositing Ag or the like. And an infrared light reflecting portion 12b as initialization signal forming means.

Here, by providing such a rotary reflector 12, the infrared light L of the light from the light source 2 usually passes through the rotary reflector 12 as shown by a broken line in FIG. Although it does not reach the light modulation element 3, the infrared light reflection part 12b
When light comes on the optical path, the extracted light including infrared light enters the spatial light modulator 1.

Then, the rotary reflecting plate 12 is synchronized with the input of the writing CRT 6 in the same manner as in the first embodiment described above, and at the same time as the timing between the first signal light and the second signal light. By rotating the external light reflecting portion 12b so as to pass on the optical path, the signal extraction light 200 can include reset light for preventing the influence of the first signal light from affecting the second signal light. Become.

In the above description, the rotation filter 1
Although the notch 10a is provided at 0 and the infrared light reflecting portion 12b is provided at one position on the rotary reflection plate 12, the present invention is not limited to this, and the rotation speed is adjusted in accordance with the input switching timing. If it is changed, two or more places can be provided.

Next, a video projector according to a fifth embodiment will be described.

FIG. 9 is a diagram showing the configuration of an image projection apparatus according to the present embodiment, which includes a spatial light modulator 1, a light source 2, a polarization beam splitter 3, a projection lens 4, a screen 5,
It has a writing CRT 6 and a writing optical system fiber plate 7, and has an initialization means composed of a synchronous shutter 15, a cold mirror 16 and a reflecting mirror 17 instead of the rotary filter 10 and the rotary reflecting plate 12 described above. It is a thing.

The cold mirror 16 transmits infrared light, and the synchronous shutter 15 opens at a timing between the first signal light and the second signal light. The reflection mirror 17 has a convex surface, and reflects the infrared light L transmitted through the cold mirror 16 as shown in FIG.

With such a configuration, the signal extraction light 200 from the light source 2 is reflected by the cold mirror 16, and the light other than the infrared light is reflected by the polarization beam splitter 3.
Is converted into polarized light, while the infrared light L included in the signal extraction light 200 passes through the cold mirror 16, and the optical path is changed by the reflection mirror 17 to directly direct the spatial light modulator 1.
I will be heading to. Since the infrared light L is blocked by the normally closed synchronous shutter 15, it does not enter the spatial light modulator 1. In this state, light not including infrared light from the polarizing beam splitter 3 is modulated by the liquid crystal layer and emitted.

On the other hand, this synchronous shutter 15
6 is opened at the timing of switching the input from the second signal light, that is, at the timing between the first signal light and the second signal light, the signal light 200 is superimposed on the PC layer of the spatial light modulator 1 with the infrared light. L is incident. Thereby, the state of the PC layer formed by the first signal light can be reset, and the second signal light can be prevented from being affected.

Next, an image projection apparatus according to a sixth embodiment will be described.

FIG. 10 is a diagram showing a configuration of an image projection apparatus according to the present embodiment, in which a spatial light modulator 1, a light source 2,
A polarization beam splitter 3, a projection lens 4, a screen 5, a writing CRT 6, and a fiber plate 7 for a writing optical system are provided, and an initialization unit including an infrared light reflection mirror 14, a reflection mirror 16, and a synchronous shutter 15 is provided. ing. The light source 2 is a spatial light modulator 1
It is provided on the side.

Here, the infrared light reflecting mirror 14 is
And the reflected infrared light L is directed toward the spatial light modulator 1. The signal extracting light 200 from the light source 2 is removed by the infrared light reflecting mirror 14 in a state where the infrared light is removed.
, Then reflected, and further polarized light splitter 3
And is incident on the spatial light modulator 1. Then, this incident light is modulated by the signal light from the CRT 6 and then output on the screen 5 as output light 201.

The infrared light L reflected by the infrared light reflecting mirror 14 travels to the spatial light modulator 1, but the infrared light L is blocked by the normally closed synchronous shutter 15. , Does not enter the spatial light modulator 1.

On the other hand, this synchronous shutter 15
6, the signal is opened at the timing of switching the input from the first signal light, that is, at the timing between the first signal light and the second signal light. Becomes incident. Thereby, the state of the PC layer formed by the first signal light can be reset, and the second signal light can be prevented from being affected.

Next, an image projection apparatus according to a seventh embodiment will be described.

FIG. 11 is a diagram showing a configuration of an image projection apparatus according to the present embodiment, in which a spatial light modulator 1, a light source 2,
Polarizing beam splitter 3, projection lens, screen 5,
A cold mirror 8 and a reflecting mirror 9 are provided. On the output side of the spatial light modulator 1, a reset light source 18 for generating infrared light for reset, which is different from the light source 2 as initialization means, is provided. By operating the light source 18 in response to the switching of the input light from the CRT 6, it is possible to prevent a change in the PC layer due to the first signal light from affecting the second signal light.

Next, an image projection apparatus according to an eighth embodiment will be described.

FIG. 12 is a diagram showing a configuration of an image projection apparatus according to the present embodiment, in which a spatial light modulator 1, a light source 2,
It includes a polarizing beam splitter 3, a projection lens 4, a screen 5, a cold mirror 8, and a reflecting mirror 9, and also includes an initialization unit including a reset light source 19 for generating infrared light for reset and a synchronous shutter 15. ing.

Then, by opening the synchronous shutter 15 in synchronization with the switching timing of the input light from the CRT 6, the change of the PC layer due to the first signal light is reset,
It is possible to have no effect on the second signal light. Note that the reset light source 19 may be constantly turned on.

In the above description, a light source using a metal halide lamp 2b as the light source 2 has been described, but a light source using a halogen lamp, an Hg arc lamp, or the like may be used. In the fifth and sixth embodiments, an LED light source or the like can be used.

Further, when the liquid crystal layer is different from the polarized liquid crystal layer, the polarization beam splitter 3 can be replaced with a simple beam splitter. Further, the CRT 6 used as the source of the write signal is not limited to this, but may be an LED.
A panel, a laser scanning device, or the like can be used as long as it can form an optical image. Also, besides the fiber plate described as the writing optical system, a plate lens,
Use of a lens imaging system, a reflection imaging system, or the like is also possible.

[0067]

As described above, according to the present invention, light having a sensitivity wavelength that changes the photoconductivity of the photoconductive layer contained in the signal extraction light is transmitted through the dielectric mirror layer and the like. The photoconductive layer can be reset from the signal extraction side. This makes it possible to reset from a position other than the photoconductive layer side, thereby reducing the limitation on the configuration on the writing side of the incident image, and making use of advantages such as miniaturization and no adjustment.

Further, the initialization means provided between the light source and the spatial light modulator returns the photoconductivity of the photoconductive layer changed by the signal light to the initial value before the next signal light is incident. The next signal light can be prevented from being affected by the previous signal light.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a structure of a spatial light modulator according to a first embodiment of the present invention.

FIG. 2 is a table showing a spectral sensitivity of a PC layer of the spatial light modulator.

FIG. 3 is a table showing a spectral reflectance of a dielectric mirror of the spatial light modulator.

FIG. 4 is a sectional view showing the structure of a spatial light modulator according to a second embodiment of the present invention.

FIG. 5 is a diagram showing a configuration of a video projection device according to a third embodiment of the present invention.

FIG. 6 is a plan view of a rotation filter of the image projection device.

FIG. 7 is a diagram showing a configuration of a video projection device according to a fourth embodiment of the present invention.

FIG. 8 is a plan view of a rotating reflector of the image projection device.

FIG. 9 is a diagram showing a configuration of a video projection device according to a fifth embodiment of the present invention.

FIG. 10 is a diagram showing a configuration of a video projection device according to a sixth embodiment of the present invention.

FIG. 11 is a diagram showing a configuration of a video projection device according to a seventh embodiment of the present invention.

FIG. 12 is a diagram showing a configuration of a video projection device according to an eighth embodiment of the present invention.

FIG. 13 is a configuration diagram of an image projection apparatus using a conventional spatial light modulator.

[Description of Signs] 1, 1 ', 1A Spatial light modulator 100, 100' Light modulator 101, 107 Transparent substrate 102, 106 Transparent electrode 103 PC layer 104 Dielectric mirror layer 108 Light shielding layer 2 Light source 200 Signal extraction light 202 Signal light 6 CRT 10 Rotating filter 10a Notch 12 Rotating reflector 12b Infrared light reflecting part 14 Infrared light reflecting mirror 15 Synchronous shutter 16 Cold mirror 17 Reflecting mirror 18, 19 Reset light source L Infrared light

Claims (9)

[Claims] 1. A spatial light modulator comprising: a photoconductive layer provided between a pair of transparent substrates on a signal input side and a signal extraction side each having a transparent electrode formed thereon; a dielectric mirror layer; and a light modulation layer. In the light having a sensitivity wavelength that changes the photoconductivity of the photoconductive layer included in the light incident from the transparent substrate on the signal extraction side, light having a predetermined sensitivity wavelength passes through the dielectric mirror layer. A spatial light modulation device, wherein a reflection wavelength range of the dielectric mirror layer is set so as to transmit light. 2. A photoconductive layer, a light shielding layer, a dielectric mirror layer, and a light modulation layer provided between a pair of transparent substrates on a signal input side and a signal extraction side each having a transparent electrode formed thereon. In the spatial light modulator, among the light having a sensitivity wavelength that changes the photoconductivity of the photoconductive layer included in the light incident from the transparent substrate on the signal extraction side, the light having a predetermined sensitivity wavelength is the dielectric material. A spatial light modulator, wherein a reflection wavelength range of the dielectric mirror layer and a light shielding wavelength range of the light shielding layer are set so as to transmit through the body mirror layer and the light shielding layer. 3. The spatial light modulation device according to claim 1, wherein a liquid crystal layer is used as the light modulation layer. 4. The space according to claim 1, wherein the transparent electrode and the transparent substrate are transparent to visible light and transparent to light incident from each of the transparent substrates. Light modulation element. 5. A spatial light modulator, a writing section provided on a signal input side of the spatial light modulator so that signal light is incident on the spatial light modulator, and a signal extracting light for extracting the signal light. And a light source provided on a signal extraction side of the spatial light modulator so that the light is incident on the spatial light modulator. The spatial light modulator according to claim 1, wherein the spatial light modulator is Meanwhile, between the spatial light modulator and the light source, initialization means for returning the photoconductivity of the photoconductive layer changed by the signal light to an initial value before the next signal light is incident. An image projection device, comprising: 6. The light modulating layer initializes the light modulating layer by causing light having a predetermined sensitivity wavelength of the light having a sensitivity wavelength that changes the photoconductivity of the photoconductive layer to be incident on the spatial light modulating element. 6. The apparatus according to claim 5, wherein
The image projection device according to claim 1. 7. The apparatus according to claim 1, wherein said initialization means has initialization signal forming means for forming light having a predetermined sensitivity wavelength for initializing said light modulation layer from said signal extraction light. 7. The image projection device according to 5 or 6. 8. The image projection apparatus according to claim 7, wherein said initialization means superimposes the light having the predetermined sensitivity wavelength on the signal extraction light and enters the spatial light modulation element. 9. The image according to claim 5, wherein said initialization means forms light of said predetermined sensitivity wavelength using a light source different from a light source on which said signal extraction light is incident. Projection device.