JPH0463320A - Photo-photo conversion element - Google Patents

Abstract

PURPOSE:To obviate the generation of adverse influence by a photoconductive effect in an optical modulating material layer by laminating a specific dielectric mirror layer and the optical modulating material layer. CONSTITUTION:The dielectric mirror layer DML having the wavelength selectivity to reflect the light of visible light and the light in the wavelength region of reading out light RL and allows the transmission of erasing light EL is provided on the photo-photo conversion element PPC. The dielectric mirror layer constituted of a dichroic filter consisting of multiple layers of thin films of, for example, SiO2 and thin films of TiO2 is used as the DML. The optical modulating material layer PML used as the optical member which changes the state of the light according to the intensity distribution of impressed electric fields is formed of a material, such as bismuth silicate, which has the photoconductive effect and primary photoelectrical effect in combination and exhibits anisotropy only in the electric field. This element is subjected to writing with writing light WL and to reading out with reading out RL.

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to a light-to-light conversion element and an imaging device.

(Prior Art) Examples of light-to-light conversion elements configured to input an optical image and output an optical image include, for example, a liquid crystal optical modulator, a photoconductive Bockels effect element, and a microchannel. Space variables such as type light variables, etc.
Alternatively, there are various types of II-formed elements such as elements constructed using photochromic materials. .

It has long been attracting attention as an element for optical parallel processing in optical computers and as an element for image recording, and the applicant's company is currently developing high-resolution imaging devices using light-to-light conversion elements. We also make suggestions.

FIG. 5 is a side sectional view showing an example of the configuration of a conventional light-to-light conversion element. In the light-to-light conversion element shown in FIG. 5, 1 and 2 are glass plates, and 3 and 4 are transparent electrodes. , 5, 6.1
1 is a terminal, and 7 is a photoconductive layer.

12 is a light shielding layer, 8 is a dielectric mirror, and 9 is an optical member that changes the state of light according to the intensity distribution of the applied electric field (for example, a light modulating material layer such as a lithium niobate single crystal, or a nematic liquid crystal). layer), WL is writing light, RL is reading light, and EL is erasing light.

In the light-light conversion element shown in FIG.
A circuit consisting of an electric wire 1o and a changeover switch SW is connected to the switch 6, and the movable contact of the changeover switch SW is controlled by a changeover control signal supplied to the input terminal 11 of the changeover switch SW. The fixed contact is switched to the WR side, a voltage of 10 is applied between the transparent electrodes 3 and 4, and an optical member (for example, , a light modulating material layer such as a lithium niobate single crystal, or a nematic liquid crystal layer) 9).

Writing light W from the glass plate 1 side in the light-light conversion element
When the writing light WL is transmitted through the glass plate 1 and the transparent electrode 3 and reaches the photoconductive layer 7, the electrical resistance value of the photoconductive layer 7 is determined by the optical resistance caused by the incident light that has reached it. Since the charges change in accordance with the image, a charge image corresponding to the optical image caused by the incident light reaching the photoconductive layer 7 is generated at the interface between the photoconductive layer 7 and the light shielding layer 12.

In addition, in the state where the movable contact of the changeover switch SW is switched to the fixed contact WR side as described above, the electric
Transparent electrode 3 to which a voltage of is applied via terminals 5 and 6
, 4, the above-mentioned photoconductor 17; and a light modulating material layer (or nematic liquid crystal layer) such as a lithium niobate single crystal, which is provided in series with the light shielding layer 12 and the dielectric mirror 8. ) 9, since an electric field with an intensity distribution corresponding to the charge image generated by the writing light is applied to the interface between the photoconductor W7 and the light shielding layer 12 as described above.
Due to the electro-optic effect of the light modulating material layer 9, the readout light RL incident from the glass plate 2 side becomes reflected light containing image information corresponding to the electric field strength applied to the light modulating material layer 9, The light is emitted from the glass plate 2 side.

Then, as described above, it is projected onto the glass plate 2 side.

Transparent type! i4→light modulating material M9→dielectric mirror 8→light shielding layer 12 Among the readout light RL that is not reflected by the dielectric mirror 8, the light that is not reflected by the dielectric mirror 8 is transferred to the photoconductive layer 7 side by the light shielding layer 12. Since the light is blocked so that it does not advance, even if the readout light RL is projected onto the glass plate 2 side, the electric resistance value of the photoconductive layer 7 will not change due to the projection of the readout light RL. The photoconductive layer 7 and the light shielding layer 1
The charge image generated at the interface between 2 and 1 in correspondence with the optical image caused by the incident light is not changed.

By the way, in the light-photointensity conversion element shown in FIG. 5 described above::,
*In order to erase the information written in the light-to-light conversion element by the writing light WL, the switching 1ffll signal is supplied to the input terminal 11 of the switching control signal in the changeover switch SW, and the movable contact of the changeover switch SW is applied. is switched to the fixed contact E side, and the potentials of the terminals 5 and 6 in the light-to-light conversion element are made the same so that no electric field is generated in the transparent electrode 3° 42, and then
By inputting the erasing light EL with a certain intensity from the above-mentioned glass plate 1 side, which is the incident side of the writing light WL, the above-mentioned erasing light EL is applied to the glass plate 1 and the transparent electrode 17.
43 to the photoconductive layer 7 to lower the electrical resistance value of the photoconductive layer 7 and erase the charge image generated at the interface between the photoconductive layer 7 and the light shielding layer M12. Ta.

In this way, in the fifth conventional light-to-light conversion element, the incident side of the erasing light used to erase information that has already been written is made the same as the incident side of the incoming light WL. This is because there is a light shielding layer 12 between the readout light RL incident side and the photoconductive layer 7, so when the erasing light is made incident from the readout light RL incident side, the erasing light is The light is blocked by the light shielding layer 7112 described above and does not reach the photoconductive layer J7. Therefore, when the erasing light is made incident from the side where the readout light RL is incident, the photoconductive layer 7 and the light shielding layer 12 are This is because the charge image generated at the boundary surface cannot be erased.

The above point applies, for example, to an imaging device configured such that an imaging optical system is required to be provided on the side where the writing light Wr4 is incident, and in other cases where the erasing light is incident on the side where the writing light WL is incident. This becomes a big problem when the light-to-light conversion element is used in a device with a configuration in which it is difficult to install the device.

As a light-to-light conversion element capable of solving the above-mentioned problems, the applicant company has previously developed a light-to-light conversion element having a structure as shown in FIG. In addition to reflecting light in the wavelength range of the readout light,
Wave of erasing light! An optical member 8R having wavelength selectivity that allows light in the jc range to pass through, an optical member 9 that changes the state of light according to the intensity distribution of an applied electric field, a transparent pole 4, and a glass plate. In Fig. 6, 1 and 2 are glass plates, 3.4 is a transparent pole,
5 and 6 are terminals, and 7 is a photoconductive layer. 8R is an optical member having wavelength selectivity that can reflect light in the wavelength range of the reading light and transmit light in the wavelength range of the erasing light.
A dichroic filter composed of a multilayer film consisting of a thin film of TiO2 and a thin film of TiO2 can be used.

Further, 9 is an optical member that changes the state of light according to the intensity distribution of the applied electric field (for example, an optical member composed of an electro-optic effect crystal such as a lithium niobate single crystal or a nematic liquid crystal layer). In the figure, WL indicates writing light, RL indicates reading light, and EL indicates erasing light.

The seventh figure is a curved diagram illustrating the wavelength selectivity of the optical member 8R, which has wavelength selectivity such that it can reflect light in the wavelength range of the reading light and transmit light in the wavelength range of the erasing light. In FIG. 7, the optical member 8R having the characteristics shown in FIG. 7(a) below is configured as an optical low-pass filter, and
The optical member 8R having the characteristics shown in FIG. 7(b) is configured as an optical high-pass filter, and further has the characteristics shown in FIG. 7(c). The optical member 8R having the characteristics shown in FIG. 7(d) is configured as an optical bandpass filter, and the optical member 8R having the characteristics shown in FIG. It means that it is configured as .

That is, in the already proposed light-to-light conversion element shown in FIG. 6, the optical member 8R1 used as a component thereof reflects light in the wavelength range of the readout light, and The optical member 8R having wavelength selectivity capable of transmitting light in the wavelength range of light is shown in FIG.
Wavelength effects are exemplified in a) to (d).'! Therefore, the optical member SR having high selectivity can be used.

Wavelength 1 as illustrated in (a) to (d) of FIG.
My proposed light is equipped with an optical member 8R having selective retention properties.
In the light conversion element, light in a wavelength region with low light transmittance in the optical member 8R is used as the reading light to be input to the element, and light in a wavelength region with low transmittance of light in the optical member 8R is used as the erasing light to be input to the optical member SR. Light in the U-ma wavelength range with high transmittance is used, and this makes it possible for the previously proposed light-to-light conversion element to have the erasing light enter from the read-out light incident side.

When writing optical information to the already proposed light-to-light conversion element having the configuration shown in Figure 6, the optical - A circuit consisting of a power source 10 and a changeover switch SW is connected to the terminals 5 and 6 of the optical conversion element.

Input terminal 11 of the switching control signal in the switching switch SW
The movable contact of the changeover switch SW is switched to the fixed contact WR side by the switching side control signal supplied to the photoconductive layer 7. When an electric field is applied between both ends of the light-to-light conversion element and the writing light WL is made incident on the glass plate 1 side of the light-to-light conversion element, optical information is written to the light-to-light conversion element.

That is, when the writing light WL incident on the light-to-light conversion element passes through the glass plate 1 and the transparent electrode 3 and reaches the photoconductive layer 7 as described above, the electrical resistance value of the photoconductive layer 7 reaches that value. In order to change corresponding to the optical image caused by the incident light,
At the interface between the photoconductive layer 7 and the optical member 8R (optical member 8R having wavelength selectivity capable of reflecting light in the wavelength range of the reading light and transmitting light in the wavelength range of the erasing light), there is light. A charge image corresponding to the optical image caused by the incident light reaching the conductive layer 7 is generated.

In order to reproduce optical information written in the form of an optical image by incident light and a corresponding charge image from the light-to-light conversion element as described above, changeover switch SW'7) is used to change the movable contact to the fixed contact. When switched to the WR side, the voltage of the superposition 10 is applied between the transparent electrodes 13 and 4 via the terminals 5 and 6, and the voltage from the light source (not shown) is applied from the glass fLZ side. This can be done by projecting readout light RL of a constant light intensity.

In other words, the photoconductive layer 7 and the optical member 8R in the light-to-light conversion element on which optical information has been written using incident light as described above (reflects light in the wavelength range of readout light, and reflects light in the wavelength range of erasing light). Since a charge image corresponding to the optical image caused by the incident light that has reached the photoconductive layer 7 is generated at the interface with the optical member 8R) having wavelength selectivity that allows the light to pass through the photoconductive layer 7, An optical member 9 (for example, lithium niobate single crystal 9), which is provided in series with the optical member 8R with respect to the layer 7, is applied with an electric field having an intensity distribution corresponding to the optical image created by the incident light. is being done.

Since the refractive index of the lithium niobate single crystal 9 changes depending on the electric field due to the electro-optic effect, the photoconductive layer 7 is applied with an electric field having an intensity distribution corresponding to the optical image formed by the incident light. The refractive index of the niobium lithium crystal 9, which is provided in series with the optical member 8R, is the same as that of the photoconductor M7 in the light-to-light conversion element and the optical Part 8
R (while reflecting light in the wavelength range of the readout light.

Changes according to the charge image generated corresponding to the optical image caused by the incident light that reaches the light guide layer 17 at the interface with the optical member 8R) having wavelength selectivity that allows light in the wavelength range of the erasing light to pass through. Be what you are.

Therefore, when the readout light RL is projected onto the glass plate 2 side, the readout light RL projected onto the glass plate 2 side as described above changes from the transparent electrode 4 to the lithium niobate single crystal 9 to the optical member 8R ( The optical member 8R) has a wavelength selectivity capable of reflecting light in the wavelength range of the reading light and transmitting light in the wavelength range of the erasing light.

The readout light RL described above is reflected by the optical member 8R having wavelength selectivity that allows light in the wavelength range of the readout light to be reflected and light in the wavelength range of the erasing light to be transmitted, and the reflected light is reflected onto the glass plate 2 side. However, since the refractive index of the lithium niobate single crystal 9 changes depending on the electric field due to the electro-optic effect, the reflected light of the readout light RL is reflected by the lithium niobate single crystal 9 due to the electro-optic effect of the lithium niobate single crystal 9. It contains electric image information according to the intensity distribution of the electric field applied to the crystal 9, and produces a reproduced optical image on the glass plate 2 side corresponding to the optical image created by the incident light.

In the above reproduction operation, the readout light RL projected from the glass plate 2 side is transmitted through the transparent electrode 4→lithium niobate single crystal 9→optical member 8R (while reflecting light in the wavelength range of the readout light and .

The optical member 8R, which has a wavelength selectivity capable of transmitting light in the wavelength range of the erasing light, proceeds toward the photoconductive layer 7 as shown in (8R). Before reaching , the light is reflected by the optical member 8R (optical member 8R having wavelength selectivity such that it can reflect light in the wavelength range of the reading light and transmit light in the wavelength range of the erasing light). Since the light path follows the lithium niobate single crystal 9→transparent charge filler 4→glass plate 2, the above-mentioned readout light RL reaches the photoconductive layer 7 and has an adverse effect on the charge image written by the incident light. There is no such thing as giving

In this way, in the previously proposed light-to-light conversion element, the glass plate 1
A writing operation is performed by making the writing light WL enter from the side of the glass plate 2, and reproduction of the optical part is performed by making the reading light RL enter the glass plate 2 side.
The method of erasing information written in the previously proposed light-to-light conversion element shown in the drawings will be explained as follows.

When erasing the information written in the already proposed light-to-light conversion element shown in Figure 6, a switching control signal is input to the changeover switch SW connected between terminals 5 and 6 of the light-to-light conversion element. A switching control signal supplied to the terminal 11 switches the movable contact of the changeover switch SW to the fixed contact E side, electrically shorts the transparent electrodes 3 and 4, and closes the transparent electrodes 3 and 4. After making the potentials the same so that no electric field is applied between both ends of the photoconductor 117, the erasing light EL is made to enter from the glass plate 2@ in the light-to-light conversion element.

As mentioned above, the erasing light EL incident on the glass plate 2 side of the light-to-light conversion element is transmitted through the glass plate 2 → transparent electrolyte 4 → lithium niobate single crystal 9 → optical member 8R (light in the wavelength range of the readout light). Optical member 8R) having wavelength selectivity that can reflect and transmit light in the wavelength range of the erasing light reaches the photoconductive layer 7 via a path such as the photoconductive layer 7, and the erasing light E
L lowers the electrical resistance value of the photoconductive layer 7 and increases photoconductivity.
Charges formed on the interface between l17 and the optical member 8R (optical member 8R having wavelength selectivity such that it can reflect light in the wavelength range of the reading light and transmit light in the wavelength range of the erasing light). Make the statue disappear.

In this way, in the previously proposed light-to-light conversion element shown in FIG. Optical member 8I having wavelength selectivity that allows transmission?
) was formed at the interface with ? Since the tI image is erased by the erasing light that enters the light-to-light conversion element from the readout light incident side of the light-to-light conversion element, the imaging optical system is placed on the side where the writing light WL is incident. An imaging device configured such that it is necessary to provide a system.

In addition, it can be easily applied to devices having configurations in which it is difficult to provide an erasing light incident device on the side where the writing light WL is incident, and the conventional method described above with reference to FIG. The conventional problems in the light-to-light conversion element can be satisfactorily solved.

(Problem M to be solved by the invention) By the way, as is clear from the explanations regarding the light-to-light conversion elements proposed so far, in the light-to-light conversion element, as one of its constituent members, An optical member 9 that changes the state of light according to the intensity distribution of an electric field is used, and in the description of the already proposed light-to-light conversion element,
It has been described that as the optical member 9, for example, an electro-optic effect crystal such as a lithium niobate single crystal, or a nematic layer 4.1 can be used.

However, an anisotropic M& such as the lithium niobate single crystal described above causes WL refraction when an electric field is applied, but in the absence of an electric field, that is, when the applied electric field is ? 7) Even in the initial state, birefringence occurs due to the anisotropy of the crystal, so the phase difference between the ordinary and extraordinary rays that pass through the crystal also changes depending on the thickness of the anisotropic crystal, so the unevenness of the crystal thickness This results in the unevenness of the phase difference between the ordinary ray and the extraordinary ray in the initial layer state as described above. Ninth, when manufacturing the optical member 9 that does not cause the above-mentioned uneven phase difference, high-precision optical polishing is required.

Further, when a nematic liquid crystal layer is used as the optical member 9 that changes the state of light according to the intensity distribution of the applied electric field, there is a problem that it is difficult to obtain the optical member 9 with excellent attachment characteristics.

Now, as the optical member 9 used in the light-to-light conversion element, that is, the optical member 9 that changes the state of light according to the intensity distribution of the applied electric field, the already proposed light-to-light conversion element is being explained. In addition to electro-optic effect crystals such as lithium niobate single crystals and nematic liquid crystal layers, which were exemplified in Along with having.

Materials that exhibit anisotropy only in an electric field are also used, and light s! ! An optical member that changes the state of light according to the intensity distribution of the applied electric field by using a substance that has both the primary electro-optic effect and the primary electro-optic effect and exhibits anisotropy only in the electric field. 9, the optical member 9 is constructed using an electro-optic effect crystal such as the lithium niobate single crystal described above, or a nematic liquid crystal layer.
In addition, materials that have both a photoconductive effect and a primary electro-optic effect, such as bismuth silicate (BSO), have a photoconductive effect. A solution to this problem has been sought since it interferes with the operation of the light-to-light conversion element.

(Means for Solving Problem 11) The present invention includes a first transparent electrode, a photoconductive layer, and a wavelength selectivity capable of reflecting light in the wavelength range of continuous light and transmitting erasing light. A light-to-light conversion element formed by laminating a dielectric mirror layer, a light modulating material layer whose light state changes only in an electric field, and a second transparent electrode, the first transparent electrode, and a photoconductive layer. , a dielectric mirror layer having wavelength selectivity that can reflect light in the wavelength range of the reading light and transmitting the erasing light, and a dielectric mirror layer that has both a photoconductive effect and a primary electro-optic effect, and has an electric field. It comprises a light modulating material layer that exhibits anisotropy only in the middle and a second transparent electrode, and is configured to transmit only light in a wavelength range that does not cause a large photoconductive effect to the light modulating material layer. a first transparent electrode, a photoconductive layer, and a dielectric mirror layer having wavelength selectivity capable of reflecting light in the wavelength range of readout light and transmitting erasing light; , a light modulating material layer that has both a photoconductive effect and a first-order electro-optic effect and exhibits anisotropy only in an electric field, a second transparent electrode, and a large photoconductive layer in the above-mentioned light intensity adjusting layer. A light-to-light conversion element formed by laminating an optical filter that transmits and reads only light in a wavelength range that does not produce an effect, and an object to be photographed by light in the visible range from the first transparent electrode side of the light-to-light conversion element. To provide a 'Jk image device, comprising means for inputting optical information as writing light, and means for selectively inputting readout light and erasing light from the optical filter side of the light-to-light conversion element. It is.

(Example) Hereinafter, specific details of a light-to-light conversion element of the present invention and an image sensor configured using the light-to-light conversion element will be described in detail with reference to the accompanying drawings.

FIG. 1 is a side sectional view of one embodiment of the light-to-light conversion element PPC of the present invention. In the light-to-light conversion element PPC shown in FIG. 1, 1 and 2 are glass plates, and 3 is a 4 is the second transparent electrode, 5.6 is the terminal, PCL is the photoconductive layer, WL is the writing light, RL is the reading light, EL is the erasing light, and DML is the visible light. A dielectric mirror layer having a wavelength selectivity capable of reflecting light in the wavelength range of the reading light RL and transmitting the erasing light EL, the dielectric mirror layer iC2 having the wavelength selectivity described above. , i*-rich dichroic filter with a multilayer film. Therefore, a dichroic filter with l:A can be used.

In addition, PML is used as an optical member that changes the state of light according to the intensity distribution of the applied electric field.
The first material layer was formed of a material such as bismuth silicate (CBSO) that has both the photonic effect and the first-order electro-optic effect, and also exhibits anisotropy only in an electric field. This is a light modulating material layer.

Furthermore, PF is an optical filter provided as necessary, and this optical filter PF is the light modulating material layer PM described above.
It is constructed so that it can transmit only light in a wavelength range that does not cause a large photoconductive effect on L.

Figure 2 shows that a light modulating material layer PML made of a material that has both a photoconductive effect and a first-order electro-optic effect and exhibits anisotropy only in an electric field is The relationship of the photoconductive effect with respect to the wavelength of light in bismuth silicate (BSO), which is cited as an example of the constituent material of the light modulating material layer PML when used as an optical member that changes the shape of light according to the intensity distribution, is shown below. FIG.

Bismuth silicate (BSO) shown in FIG.
), it can be seen that the wavelength region in which no large photoconductive effect occurs in bismuth silicate (BSo) is the long wavelength region. .

FIG. 3 shows each structure of a light-to-light conversion element of an embodiment in which the light-to-light conversion element PPC of the present invention is constructed using bismuth silicate (BSO) as a constituent material of the light modulating material layer PML. 3 is a diagram showing the light transmittance characteristics with respect to the optical wavelength of a portion, and the curve PF in this FIG. 3 is the optical filter P.
It is the light transmittance characteristic for the light wavelength of F, and the third
The curve DML in the figure is a dielectric mirror D with wavelength selectivity.
It is a light transmittance characteristic with respect to the light wavelength of ML, and the wavelength λ1 is the wavelength of the reading light RL, and λ2 is the wavelength of the erasing light EL. Note that in the light-to-light conversion element PPC of the present invention, the writing light WL is the 33rd! ! It is assumed that light in the wavelength range indicated as visible light will be accepted.

That is, the light-to-light conversion element of the present invention shown in FIG. 1 has both the photoconductive effect and the primary electro-optic effect as described above, and also exhibits anisotropy only in an electric field. The light modulating material layer PML in the light-to-light conversion element of the present invention shown in FIG. , wavelength of light versus photoconductive current (photoconductive current) as shown in Figure 2.
If it is formed using bismuth silicate (B SO) having the characteristics, the bismuth silicate (B SO)
The wavelength range of light that does not cause a large photoconductive effect on the light modulating material layer PML formed by SO) is a wavelength range that is longer than the long wavelength range in the visible light wavelength range, as seen from the characteristic curve shown in the second diagram. It turns out that it may be assumed that

Therefore, in the light-to-light conversion element of the present invention shown in FIG. , light having a wavelength that does not cause a photoconductive effect in the light modulating material layer PML is selected and used.

FIG. 3 illustrates readout light RL with a wavelength λl and erase light EL with a wavelength λ2, which are selectively used in a wavelength range longer than the wavelength range of visible light. It is clear that even if it passes through the PML, it will not cause a large photoconductive effect on the light modulating material layer PML.

Further, as described above, the optical filter PF has a light modulating material layer P.
The purpose is to allow only light in a wavelength range that does not cause a large photoconductive effect to pass through the ML, so the second
Of the light incident on the light-light conversion element PPC from the transparent ffr14 side, light in a wavelength range that causes a large photoconductive effect on the light modulating material layer PML is effectively blocked by the optical filter PF. As a result, light in a wavelength region that causes a large photoconductive effect in the light modulating material layer PML can be prevented from being supplied to the light modulating material layer PML.

However, the light modulating material layer PML has a large photoconductive effect! It goes without saying that the above-mentioned optical filter PF is unnecessary if no light in the wavelength range that causes this occurs.

Since the dielectric mirror DML having 'tL length selectivity has the property of reflecting light in the visible range (as mentioned above), the light in the visible range that is incident from the first transparent electrode 3 side The optical information of the subject is not supplied to the light f true material layer PML, and therefore, no light that would cause a large photoconductive effect is incident on the light modulating material MPML. - In the light conversion element, even if the light modulating material layer PML is made of a material that has both the photoconductive effect and the first-order electro-optic effect and exhibits anisotropy only in an electric field, the light-light The conversion element does not suffer from the aforementioned problems due to the photoconductive effect.

FIG. 4 is a perspective view showing a schematic configuration of an imaging device configured using the light-to-light conversion element of the present invention configured as shown in FIG. The PPC shown in FIG. 1 is a light-to-light conversion element PPC having the same structure as the light-to-light conversion element PPC shown in FIG.

1st i! ! and the light-light conversion element P shown in FIG.
When writing optical image information to a PC, a circuit consisting of a power supply 10 and a changeover switch SW is connected to terminals 5 and 6 of the light-to-light conversion element, and a circuit consisting of a power supply 10 and a changeover switch SW is connected to an input terminal 11 of a changeover control signal in the changeover switch SW. With the supplied switching control signal,
Switch the movable contact of the changeover switch SW to the fixed contact WR side.

Applying the voltage of the power source 10 to the transparent electrodes 3 and 4 described above,
An electric field is applied between both ends of the photoconductive layer PCL, and writing in the visible range is performed from the upper side of the glass plate in the light-to-light conversion element PPC from the object O shown in FIG. 4 through the imaging lens L. When the light WL is incident, optical information is written into the light-to-light conversion element PPC.

In Fig. 4, 0 is the subject, L is the photographic lens, BSI,
BS2 indicates that the beam splitter PSr is the light source of the readout light (for example, a flying spot scanner using a laser beam can be used as the light source of the readout light PSr, and in the following description, the light source PSr of the readout light is 1). ), PSe is the light source of the erasing light, PLP is the polarizing plate, PD is the photodetector, and the light-luminous intensity is exemplified in Figure 1M4. 'JIk image system configured with m-element PPC! In.

The optical images # and O are incident on the light-to-light conversion element PPC from the glass plate 1 side as writing light by the image carrier lens B.

That is, when the writing light WL incident on the light-to-light conversion element PPC passes through the glass plate 1 and the transparent electrode 3 and reaches the photoconductive layer PCL as described above, the electrical resistance lid of the light guide tlPcL detects the incident light that has reached it. In order to change corresponding to the optical image caused by light, a dielectric mirror DML having photoconductivity, PCL and wavelength selectivity (light in the wavelength range of read light RL and writing light WL in the visible range) is used. Along with reflecting
At the interface with the dielectric mirror DML having wavelength selectivity that allows light in the wavelength range of the erasing light EL to pass through, there is a charge image ( In No. 41!I, the photoconductive layer PCL in the light-to-light conversion element PPC is shown as an inverted A-shaped charge image for the A-shaped optical image of the subject ○)
occurs.

The optical information written in the form of a charge image corresponding to the optical image by the writing light WL as described above is reproduced from the light-light conversion element PPC.

When the movable contact of the changeover switch SW is switched to the fixed contact WR side, the voltage of the power supply 10 is applied to the terminals 5 and 6.
The voltage is applied between the transparent electrodes 3 and 4 via the
The readout light RL, which is a coherent light emitted from the readout light 1 [Psr, which is configured as a flying spot scanner for laser light, is transmitted through a beam splitter BSI, then reflected by a beam splitter BS2, and then passed through an optical filter. When projected onto the light-light conversion element PPC from the glass plate 2 side via the PF.

When a flying spot scanner using a laser beam is used as the light 1 [Psr of the readout light RL], the reproduced optical image appearing on the glass plate 2 side of the light-to-light conversion element PPC is constructed by flying spot scanning. Therefore, the light of the reproduced optical image passes through the beam splitter 7, the polarizing plate PLP, and the light from the photodetector PD passes through the polarizer PLP. A video flaw symbol corresponding to the optical image will be output.

That is, as described above, the photoconductive layer PCL and the dielectric mirror (writing light WL and readout light RL
A dielectric mirror having a wavelength selectivity that can reflect light in the wavelength range of 1 and transmit light in the wavelength range of the erasing light EL) At the interface with DML, the writing light WL that has reached the photoconductive layer PCL is Since a charge image corresponding to an optical image is generated, the light modulating material layer PML provided in series with the dielectric mirror DML with respect to the photoconductive layer PCL, that is, the photoconductive effect and 1 The light modulating material layer PML is formed of a material (bismuth silicate (BSO)) that has both the electro-optic effect and exhibits anisotropy only in an electric field.
The structure is such that an electric field with an intensity distribution corresponding to that before optics is applied by L.

As mentioned above, light formed from a substance (such as bismuth silicate (BSO)) that has both the photoconductive effect and the primary electro-optic effect and exhibits anisotropy only in an electric field. Since the refractive index of the modulator layer PML changes depending on the electric field due to the first-order electro-optic effect, the photoconductive layer described above is in a state where an electric field with an intensity distribution corresponding to the optical image due to the signature light WL is present. The refractive index of the light modulating material layer PML, which is provided in series with the dielectric mirror DML having wavelength selectivity with respect to PCL, is determined by light-to-light conversion by writing optical image information by the writing light WL described above. The charge image is generated at the interface between the photoconductive layer PCL and the dielectric mirror DML in the element PPC in accordance with the optical image caused by the writing light WL that has reached the photoconductive layer PCL.

Therefore, when the readout light RL is projected onto the glass plate 2 side, the readout light RL projected onto the glass plate 2 side as described above changes from the glass plate 2 to the optical film 3? F→Transparent electric basket 4→
A light modulating material layer PML→it formed of a material that has both a photoconductive effect and a first-order electro-optic effect and exhibits anisotropy only in an electric field (for example, bismuth silicate (BSC)) Body mirror (dielectric mirror that has wavelength selectivity that can reflect light in the wavelength range of the writing light WL and read light R2 and transmit light in the wavelength range of the erasing light EL) Proceeds as DML→ Of the light that is incident on the light-to-light conversion element PPC together with the readout light RL described above, light in a wavelength range that causes a large photoconductive effect on the light modulating material layer PML is incident. Only when the light enters the light modulator layer PML is it removed by the optical filter PF, and light in a wavelength range that causes a large photoconductive effect in the light modulating material layer PML does not enter the light modulating material layer PML. In this case, it goes without saying that the optical filter PF described above is unnecessary.

The dielectric mirror DML has wavelength selectivity such that it can reflect light in the wavelength range of the visible writing light WL and read light RL, and transmit light in the wavelength range of the erasing light EL. Like light, fjIFtll! PM
Readout light R passing through L and reaching dielectric mirror DML
L returns to the glass plate 2 side as reflected light, but it is not possible to use materials such as bismuth silicate (for example, bismuth silicate ( A light modulating material layer 1 formed of BSO))
Since the refractive index of pML changes depending on the electric field due to the first-order electro-optic effect, the reflected light of the readout light RL is reflected from the light modulating material layer P.
Due to the first-order electro-optic effect in ML, the light modulating material layer PML
It contains image information according to the intensity distribution of the electric field applied to the image, and produces a reproduced optical image on the glass plate 2 side corresponding to the optical image created by the incident light.

In the above-described reproduction operation, the readout light RL projected from the glass plate 2 side has both the optical filter PF → the transparent electrode 4 → the photoconductive effect and the primary electro-optic effect, as well as the electric field. Substances that exhibit anisotropy only inside (
For example, a light modulating material layer formed of bismuth silicate (BSO)? ML-+ dielectric mirror (writing light WL
and IIt that can reflect light in the wavelength range of the reading light RL and transmit light in the wavelength range of the erasing light EL.
dielectric mirror with sensitivity) DML →; Uni Hikari J
The readout light RL proceeds toward the t-layer PCL.
Before the light reaches the photoconductor PCL, a dielectric mirror (wavelength selection that can reflect light in the wavelength range of the writing light WL and read light RL and transmit light in the wavelength range of the erasing light EL) is used. By being reflected by the DML (a dielectric mirror with polarity), it has both a photoconductive effect and a first-order electro-optic effect, and also exhibits anisotropy only in an electric field (for example, bismuth silicate ( Photochangeable shoulder material layer PML formed by BSO))→transparent electrode 4→
Since the light path follows the optical path from the optical filter PF to the glass plate 2, the above-mentioned readout light RL will not have an adverse effect on the charge image caused by the above-mentioned write light WL.

Man 4The image pickup device shown in the figure requires writing and reading out images of different subjects at each predetermined time length to generate a video signal. In order to write and read images of different objects at each predetermined time length, a new optical image of the object is written on the time shelf at each predetermined time length. Before the optical image is written, it is necessary to erase the charge image corresponding to the previously written optical image.

The above-mentioned erasing operation in the imaging device is performed during a predetermined time before new optical images are written one after another on the time axis, and it is the image output from the photodetector@PD. As described above, the terminal of the light-to-light conversion element PPC is performed in correspondence with the vertical blanking period in the video signal output from the photodetector PD. 5,6
Due to the switching control signal supplied to the input terminal 11 of the switching control signal in the switching switch SW, which is read directly between
The movable contact of the changeover switch SW is switched to the fixed contact E side, and the transparent electrodes 3 and 4 are electrically connected to each other to bring the transparent electrodes 3 and 4 to the same potential. After the electric field is not applied between both ends of the PCL, the erasing light EL is made incident from the glass plate 2 side of the light-to-light conversion element PPC. The above-mentioned erasing light EL is connected from the erasing light 'fl P S a in FIG. 4 to the beam splitter BSL.
, BS2 from the glass plate 2 side of the light-to-light conversion element PPCk.As mentioned above, the glass plate 2I of the light-to-light conversion element PPC! I
The erasing light EL incident on the glass plate 2 → optical filter P
F → Transparent electrode 4 → Formed from a substance that has both a photoconductive effect and a primary electro-optic effect and exhibits anisotropy only in an electric field (for example, bismuth silicate (BS○)) Light modulating material layer PML → dielectric mirror (dielectric mirror having wavelength selectivity capable of reflecting light in the wavelength range of the IF included light WL and readout light RL, and transmitting light in the wavelength range of the erasing light EL) ) DML → Photoconductive 1PC
The erasing light EL reaches the photoconductive IFPcL through a path like L, lowers the electrical resistance value of the photoconductive mPcL, and erases the photoconductive layer PCL and the dielectric mirror (within the wavelength range of the writing light WL and readout light RL). A dielectric mirror that reflects light and has wavelength selectivity that can transmit light in the wavelength range of the erasing light EL) erases the charge image formed at the interface with the DML.

In this way, in the light-to-light conversion element of the present invention shown in the first diagram, during a write operation, the photoconductive IPCL and the dielectric mirror (reflect light in the wavelength range of the write light WL and read light RL, and reflect light in the wavelength range of the erase light EL). The charge image formed at the interface with DML (a dielectric mirror with wavelength selectivity that allows light to pass through) is converted into light-light conversion from the incident side of the readout light RL in the light-light conversion element PPC. Since erasing is performed by the erasing light EL incident on the element PPC, it is necessary to provide an imaging optical system on the side where the writing light WL is incident, as shown in Figure 4. The present invention can be easily applied to an imaging device having a similar configuration, and other devices having a configuration in which it is difficult to provide an erasing light input device on the side where the writing light WL is incident. In addition,
The video old issue has the characteristics that it is easy to collect, trim, and other m-image signals 131I, and it is also easy to record and reproduce using a recording member that has reversibility 2 that can erase previously recorded signals. -*:i configured using a light-light conversion element as an imaging device for generating
Violet is an imaging device that has been commonly used for a long time.
That is, compared to an imaging device that uses an imaging lens to convert an optical image of a subject formed on a light layer conversion section of an imaging device such as an imaging tube or an ambient imaging device into a video signal.

High-quality, high-resolution reproduced images can be easily obtained.

In addition, in the description of the embodiments so far, it has been assumed that the light to be converted by the light-to-light conversion element is light in a region including visible light, but the light-to-light conversion according to the present invention The elements and imaging devices are designed to be able to be used against light in a broad sense, that is, electromagnetic radiation in the entire spectral range of radiation called electromagnetic waves (including the range from γ-rays, XS, etc. to long waves of radio waves). Of course it's a good thing.

(Effects of the Invention) As is clear from the explanation in detail 181-2, the invention is based on the first transparent electrode, the photoconductive layer, which reflects light in the wavelength range of the reading light and emits the erasing light. A light-to-light conversion element formed by laminating a dielectric mirror layer having wavelength selectivity that allows transmission, a light modulating material layer whose state of light changes only in an electric field, and a second transparent electrode, and The first transparent electrode and the photoconductive layer have wavelength selectivity that allows them to reflect light in the wavelength range of read light and transmit erase light! 1, an electric mirror layer, a light modulating material layer having both a photoconductive effect and a primary electro-optic effect and exhibiting anisotropy only in an electric field, and a second transparent electrode, A light-to-light conversion element configured to transmit only light in a wavelength range that does not cause a large photoconductive effect through the light modulating material layer, a first transparent electrode, a photoconductive layer, and the wavelength of readout light. The dielectric mirror layer has wavelength selectivity that allows it to reflect light in the area while transmitting erasing light, and has both a photoconductive effect and a secondary electro-optic effect, and is anisotropic only in an electric field. a light modulating material layer showing a second i1 layer;
A light-to-light conversion element formed by laminating the above-mentioned light modulating material layer with an optical filter that transmits and reads only light in a wavelength range that does not cause a large photoconductive effect; A means for inputting optical information of a subject using light in the visible range as writing light from the transparent electrode side, and a means for selectively inputting readout light and erasing light from the optical filter side of the light-to-light conversion element. As mentioned above, the material used as the optical member that changes the state of light according to the intensity distribution of the electric field is an anisotropic crystal such as lithium niobate single crystal. In addition to the birefringence caused by the applied electric field,
Even in the absence of an electric field, that is, in the initial state where the applied electric field is zero, birefringence occurs due to the anisotropy of the crystal, and the phase difference between the ordinary ray and extraordinary ray passing through the crystal changes depending on the thickness of the anisotropic crystal. The crystal thickness also changes, and the unevenness of the crystal thickness is cursed as the unevenness of the phase difference between the ordinary and extraordinary rays in the initial state described above.

The drawback is that high-precision optical polishing is required to produce optical components that exhibit birefringence only when an electric field is applied. When using a light modulating material layer made of a substance that exhibits anisotropy only in an electric field as an optical member that changes the state of light according to the intensity distribution of the field to configure the device, Even when the light modulating material layer is constructed using a substance that has both a photoconductive effect and a first-order electro-optic effect and exhibits anisotropy only in an electric field, the present invention still applies. According to this method, since light in a wavelength range that would cause a large photoconductive effect to pass through the light modulating material layer, it is possible to prevent the negative effect of the photoconductive effect from occurring on the light modulating material layer, and also to prevent light from passing through the light modulating material layer from the imaging lens side. An advantage can be obtained that an imaging device having a configuration that does not require input of erasing light can be easily configured.

[Brief explanation of the drawing]

FIG. 1 shows the lateral plane X of the 9-Ti array of the light-to-light conversion element PPC of the present invention, FIGS. 2 and 3, and FIG. Figures 5 and 6 are perspective views showing the aq* angle of the imaging device;
...First transparent electrode, 4...Male 2's transparent electrode, 5, 6
...Terminal, 7. Photoconductive layer. 8. Dielectric mirror, 9. Intensity distribution of applied electric field.
Optical member that changes the state of light, 10°L3
．． '-6... Power supply, 11... Terminal, 12... Light shielding layer. PF3...Light-light conversion element, ? CL... photoconductive layer,
WL...Writing light, RL...Reading light 2EL...
Erasing light, DML... A dielectric mirror layer having wavelength selectivity capable of reflecting light in the wavelength range of the writing light and reading light RL and transmitting the erasing light EL, PML.
...Light modulating material, IF, PF used as an optical member that changes the state of light according to the intensity distribution of the applied electric field
...Optical filter, SW...changeover switch, patent issuer Victor Japan Co., Ltd.

Claims (1)

[Claims] 1. A first transparent electrode, a photoconductive layer, and a dielectric mirror layer having wavelength selectivity capable of reflecting light in the wavelength range of reading light and transmitting erasing light; A light-to-light conversion element 2 formed by laminating a light modulating material layer whose light state changes only in an electric field and a second transparent electrode, a first transparent electrode, a photoconductive layer, and a wavelength of readout light. A dielectric mirror layer with wavelength selectivity that can reflect light in the area and transmit erasing light, a photoconductive effect, and 1.
The light modulating material layer has a second electro-optic effect and exhibits anisotropy only in an electric field, and a second transparent electrode, and produces a large photoconductive effect in the light modulating material layer. A light-to-light conversion element 3 configured to transmit only light in a wavelength range that is not detected, a first transparent electrode, and a photoconductive layer, which reflects light in a wavelength range of readout light and transmits erasing light. Dielectric mirror layer with excellent wavelength selectivity, photoconductive effect, and 1
A light modulating material layer that has both an electro-optic effect and exhibits anisotropy only in an electric field, a second transparent electrode, and a wavelength range that does not cause a large photoconductive effect in the light modulating material layer described above. A light-to-light conversion element formed by laminating an optical filter that transmits and reads only the light of and means for selectively inputting readout light and erasing light from the optical filter side of the light-to-light conversion element.