JPS59160127A - Optical modulating element - Google Patents

Abstract

PURPOSE:To enable efficient sepn. of divergent light and non-divergent light and to improve the utilizing efficiency of a luminous flux by providing a high polymer solid medium which generates a refractive index distribution on receiving of the heat generated according to an input signal and deforming the wave surface of the luminous flux by the refractive index distribution. CONSTITUTION:A luminous flux 10 is made incident to an optical modulating element L.M and a heating resistor 6b is selected to generate heat, then the heat heats the region in a plastic material 1 which is a thermoeffect medium facing the resistor 6b, thus forming a refractive index distribution 7 in said region. The luminous flux made incident to the resistor 6b is emitted therefrom as a luminous flux 12 having a deformed wave surface. The luminous flux 11 of which the wave surface is not deformed is shut off by a shielding filter 15a and the greater part of the luminous flux 12' having the converted wave surface is irradiated onto a photodetecting medium 14. Since a high polymer material is used as the medium 1, the wave surface of the incident luminous flux is thoroughly deformed without using a high voltage as in the prior art using the crystal as a medium.

Description

[Detailed Description of the Invention] The present invention provides light quality W) suitable for optical recording devices, optical display devices, etc.
This relates to four elements.

2. Description of the Related Art Recording or displaying using a luminous flux has been widely practiced. For this purpose, various techniques for modulating the luminous flux are known, but Japanese Patent Application Laid-Open No. 56-5523 discloses a technique for changing the electric field distribution within a crystal that has an electro-optic effect, and for changing the electric field distribution in the crystal that is generated along with this electric field distribution. A crystal that performs modulation by diffracting a light beam incident on a portion of the crystal whose refractive index changes is expensive, and when used, it is necessary to impart a predetermined polarization characteristic to the light beam incident on the crystal. Furthermore, when performing the above-mentioned modulation, in order to completely reflect the light beam at the electric field generating part inside the optical crystal material and improve diffraction efficiency, there is a restriction that the light beam is incident on the electrode as parallel as possible.

On the other hand, in recent years, attention has been focused on modulating light by utilizing the refractive index distribution due to thermal effects. Regarding light modulation using the refractive index distribution due to this thermal effect,
"Light is deflected by heat-induced refractive index change" (Nikkei Electronics August 16, 1982 issue) or rTO glass waveguide light In these examples, TiO2 crystal or glass made using ion exchange method as the thermal effect medium. etc. are used. Generally, the temperature dependence of the refractive index of a solid is small, and a high voltage is required to be applied to the resistor to obtain desired deflection characteristics. Furthermore, on each of the above sides, in order to obtain efficient deflection characteristics, it is necessary to limit the propagation position # of the incident light beam with respect to the position of the electrode or heater. That is, as mentioned above, since the temperature dependence of the refractive index is small, in order to give an appropriate phase change to the luminous flux, it is necessary to make the electrode or heater surface as close as possible to the position of the electrode or heater. It is necessary to propagate the light beam as parallel as possible.

On the other hand, the applicant proposed the use of a liquid whose refractive index change is highly dependent on temperature as a thermal effect medium in Japanese Patent Application No. 57-1.
This has already been proposed in No. 79265. However, in the case of a liquid, convection occurs due to heat generation, which tends to disturb the refractive index distribution within the liquid and increase production costs.

An object of the present invention is to provide a light modulation element that improves the drawbacks of the above-mentioned conventional elements or elements that use liquid as a thermal effect medium.

In the present invention, the above object is achieved by using a madder molecular material whose refractive index is highly dependent on temperature, such as a glass material such as acrylic or polycarbonate, as a thermal effect medium that causes a change in refractive index due to a thermal effect. This has been achieved. That is, by applying heat to a plastic material as a thermal effect medium in accordance with an input signal, a refractive index distribution is generated in the medium, and a light beam is made to enter the medium having this refractive index distribution. Modulation is performed by deforming the wavefront of the incident light beam.

In the present invention, since a polymer material (plastic material) is used as the heat effect medium, the position of the heat effect medium is restricted so that high voltage cannot be used unlike the conventional example using a crystal as a medium. Since there is no need to do this, the desired characteristics can be obtained whether the light beam incident on the element is used for transmission or reflection, and has the effect of increasing its range of applications. In particular, when reflection is used, the effect of deforming the wavefront is greater than when transmission is used, and the modulation efficiency can be increased, resulting in a large effect.

Furthermore, the present invention has the effect of increasing the degree of freedom in the manufacturing process compared to a light modulation element using a liquid as a thermal effect medium. In other words, in the case of a liquid, the manufacturing process is limited to facing a heater supported by another member, whereas in the case of using a plastic material as a heat effect medium, the plastic material is used as a support. A heater can also be provided as a support, or the plastic material can be brought into close contact with a heater provided on another support. below,
The present invention will be explained in detail.

FIG. 1 (5) shows an embodiment of the light modulation element of the present invention. In FIG. 1 (5), 1a is a transparent protective material, and 1b is a plastic material such as acrylic or polycarbonate. A thermal effect medium, 2 a thermally conductive light reflecting layer made of Al or Ta, 3 a thermally conductive insulating layer, 4 an insulating layer, and 5 a thermally conductive support substrate. . 6a, 6b, and 6c are heating resistors, and when the heating resistors generate heat, this heat is transmitted through the insulating layer 3 to the plastic material 1b, creating a temperature distribution therein and forming a refractive index distribution. . For example, as shown in the first country, when the heating resistor 6b is selected and generates heat,
This heat is transferred to the insulating layer 3 and the light reflecting layer 2 adjacent to the resistor 6b.
is transmitted to the plastic material 1 via the resistor 6b, heating the region within the plastic material facing the resistor 6b, and forming the refractive index distribution 7 in this region. This refractive index distribution 7 attenuates after a predetermined period of time as the temperature within this region decreases.

The heat generating resistors may be sequentially formed on the support body 5 using the manufacturing technique of E.C., or conversely, may be formed sequentially on the plastic material lb. In the former case, the surface of the light-reflecting layer has an uneven surface due to the thickness of the heating resistor, and the light beam incident on that surface is diffracted due to the uneven surface, but in the latter case, the uneven surface There is no diffracted light, and the latter case is desirable. When the thermal effect medium is a liquid,
The manufacturing process is limited and the heaters are sequentially formed on the support 5, which is undesirable because, as mentioned above, the surface of the light reflecting layer becomes uneven and diffracted light is generated. The present invention comprises sequentially applying a light-reflecting layer 2. Insulating insulation 3, and resistors 6a and 6b.

6c, . . . , the above-mentioned problem of generating diffracted light does not occur.

FIG. 1(B) is a diagram showing another embodiment of the light modulation element according to the present invention, and its structure is different from that of the light modulation element shown in FIG. Everything is the same except that it is not. Therefore, in the light modulation element shown in )K in FIG. 1, the heating resistors (6a to 6c) are made of a material that reflects light efficiently, and the light beam is reflected on the surface of this resistor. In this type of light modulation element, the heating resistors are arranged at close intervals, so the resistors act as if they were a diffraction grating. Includes light reflected by Therefore, as will be described later, when selectively extracting modulated light and non-modulated light, it is necessary to provide a light shielding element 1 that also blocks this diffracted light. Therefore, the light shielding means tends to be more complicated than the light modulation element shown in FIG.

The thermal effect medium used in the light modulation element of the present invention is a plastic material such as acrylic or polycarbonate, or a polymeric material such as an epoxy resin used as an adhesive. is approximately -IXIO for acrylic
, about -1,3X 10' for polycarbonate. On the other hand, in the conventional crystal mentioned above, TiO2 is -'12X10° for extraordinary light and -4,2
X 10 , PbMo0+ is -4 for extraordinary light,
I x 10', -7,2 x 10' for ordinary light,
LiNb0. is 5.3 x 1 false O-5 for extraordinary light
It is 0.56 x 10-5 with respect to ordinary light, and both values are 1/2 to 1 digit smaller than those of plastic materials.

In this way, using a plastic material as a medium for converting the wavefront of incident light requires special attention to polarization as with conventional crystals, but the absolute value is large compared to conventional crystals. It is possible to increase the phase difference between the light beam that undergoes modulation and the light beam that does not undergo modulation. This means that it can be used with normal incidence to the electrode surface or heater surface, as in the conventional example, or with other angles of incidence, eliminating restrictions on placement when assembling the modulation element into the device. It is something that can be eliminated.

FIG. 2 is a schematic perspective view showing the configuration of the light modulation element shown in FIG. 1 (5), and the numbers 1 to 6 are the same as those shown in FIG. 1 (5). However, la is a transparent protective material, and 1b is a polymer solid medium. 8 is a conductive wire, and a heating resistor (6
a, 6b, . . .) are connected to individual drive voltages so that they can be driven independently, and the other end of the heat resistor is grounded or set to a common voltage. When a voltage signal is applied to each of the conductive wires 8 and the heating resistors 6a, 6b, . . . , a refractive index distribution is generated in the thin polymer solid layer near each heating resistor. When the voltage signal is reduced to zero, this refractive index distribution is cooled and returns to the original state without refractive index distribution.

The third country is a diagram showing an embodiment of a light modulation device using the light modulation element LM with the refractive index distribution, and is an example of a case where a light beam whose wavefront is modified by the refractive index distribution is used as information light. It is. A light beam 10 is incident on the light modulation element LM,
When any heating resistor 6c among the pA resistors (6a, 6b, ...) is driven by the voltage Vi,
A refractive index distribution 7 is generated, and the light beam incident on the heating resistor 6c becomes a light beam 12 with a deformed wavefront and exits. A light beam 11 that is specularly reflected on the surface of the light reflection layer 2 and whose wavefront is not deformed by the refractive index distribution 7 is formed into an image by a lens 13a, and is blocked by a light-blocking filter 15a disposed at the image formation position. The light beam 12 whose wavefront has been deformed is partially blocked by the light shielding filter 15a, and the size of the light shielding filter 15a is set to the minimum size that allows the wavefront to be completely deformed and to illuminate the imaging spot of the light beam 11. By doing so, it is possible to irradiate most of the wavefront-converted light beam 12' onto the light-receiving medium 14.

Furthermore, in the present invention, it is possible to freely select a material with a steep gradient of the refractive index distribution as the thermal effect medium, and the divergence angle of the luminous flux due to the refractive index distribution is equal to the diffraction angle using the above-mentioned optical optical crystal. Therefore, even if the light shielding filter 15ae of the same size is used, the proportion of the divergent light that is shielded is very small in the present invention.

As described above, by applying the voltage pulse vi corresponding to the image signal to the heating resistor 6c through the conductive wire 8 or making it zero, the refractive index distribution 7 is generated or eliminated accordingly.

In that case, a blinking light spot is generated on the light receiving medium 14. The refractive index distribution generated in the vicinity of the heating resistors (6a, 6b, . . . ) by creating a conjugate relationship between the reflective surface of the light reflecting layer on the heating resistor and a point on the light receiving medium 14 by the lens 13a. An image of the generated portion can be formed as a spot on the light-receiving medium 14.

FIG. 3(B) i-1: Similarly, the light modulation element L −
FIG. 2 is a diagram showing an example of a light modulation device using M, and is an example in which a light beam that is not scattered by the refractive index distribution is used as information light. In FIG. 3(B), the light modulation element L-M
A light shielding plate 15b is provided at a position where the light beam 11 which is not subject to deformation is condensed by the lens 13a. This light shielding plate is provided with a through hole in its center so as to allow the light flux 11 to pass therethrough and block the light flux 12 shown by the broken line that is diverged by the light modulation element LM.

As described above, most of the divergent light due to the refractive index distribution is blocked by the light shielding filter 15b, and only the light beam 11 whose wavefront is not deformed passes through the light shielding filter 15b. Then, by arranging the lens 13b that makes the imaging spot formed by the lens 13a or the light shielding filter 15b in a conjugate relationship with the light-receiving sand 5-body surface 14, the original spot blinks on the light-receiving medium surface 14.

Figure 4 shows a light modulation element L-M that improves the contrast of blinking light on the light-receiving medium, that is, maximizes the light utilization efficiency.
This is a diagram for showing the state of the luminous flux incident on the
) is a view of the light modulation element viewed from the direction in which the heat generating resistors are arranged, and FIG. 4(B) is a view similarly viewed from a direction perpendicular to the direction in which the heat generating resistors are arranged. Regarding the refractive index distribution, the culm dust near the heating resistor has a steep refractive index gradient, and the divergence efficiency is highest when the light beam 16 is concentrated there.

Ushida support 5 or heating resistor (6a, 6b).

...-) Alternatively, depending on the flatness or roughness of the surface of the insulating layer 3, the light shielding efficiency of the light shielding filter 15 may deteriorate with respect to light beams other than the divergent light due to refraction and the 5 distribution. The light receiving medium 414 is irradiated as noise light. Since this noise light is irradiated onto the light-receiving medium 14 regardless of the surface of the input signal voltage noculus v1 applied from the conductive wire 8, the contrast Δ is reduced. In order to eliminate these various inconveniences, it is desirable to converge the incident light beam 16 linearly in the vicinity of the light reflecting material 1 layer 2 provided on the heating resistor, as shown in FIG. 4 (5). . 17 is a specularly reflected light beam (
18, which is indicated by a broken line, is a divergent light flux due to the refractive index distribution. Figure 4 (
B) is a view of the 101 plane shown by A-A' in 4th and (5), where 17 is a specularly reflected light beam of the incident light beam 16, and 18 is a light beam generated near the heating resistor 6c to which the image signal is input. It is a diverging light beam due to the refractive index distribution, and is scattered in different directions with respect to the specularly reflected light beam 17.

FIG. 5 is a layout diagram of an embodiment of a light modulation device for increasing the light utilization efficiency and improving the contrast of blinking light on the light receiving medium 14, as explained in FIG. A light beam emitted from a light source 19 such as a semiconductor laser or a light emitting diode is transmitted through a spherical lens 20a and an anamorphic lens 20b.
The heating resistor (6a) of the light modulation element LM is controlled by the line image forming optical system 20 constituted by the light modulating element LM.

6b, . . .) are formed in a linear manner in the arrangement direction.

The component of this linearly formed light flux in a plane perpendicular to the arrangement direction of the heating resistors is the light reflecting layer 2 in the light modulation element of FIG. Although the light beams are converged on the heating resistor, the component of the light beam within the plane defined by the arrangement direction and the optical axis toward the line image forming optical system 20 is in a parallel light beam state.

l'I! 4. Hereinafter, in this specification, the deception in the light modulation element shown in FIG. 1(5) will be referred to as (FIG. 1A) and FIG. 1(B).
In the case of the light modulation element shown in FIG. 1, it is expressed as (FIG. 1B).

Therefore, the light beam 17 that is not diverged by the polymer medium 1b takes a triangular prism-shaped optical path and enters the positive cylindrical lens 22a. The cylindrical lens 22a has its generatrix in the direction in which the heating resistors are arranged, and its focal plane is the light reflecting layer 2 (
1A) or the heating resistor (FIG. 1B). Therefore, the light beam 17 becomes an afocal light beam after passing through the cylindrical lens 22a, and the spherical lens 22. incident on b. The light beam 17 is then focused by the spherical lens 22b onto the focal plane of this l/lens.

A rectangular filter 23 having a size large enough to block the light beam 17 is provided at this focal plane, and therefore, the light beam that has not been diverged by the polymer medium 1b is blocked by the filter 23. On the other hand, from the light beam 18 diverged by the polymer medium, only the light beam in a plane perpendicular to the arrangement direction of the heating resistors becomes parallel light by the cylindrical linear lens 22a, and further by the spherical lens 22b A linear image is formed in the vicinity. Therefore, a part of the diverging light beam 18 is blocked by this rectangular filter 23, but most of the light beam is not crossed by this light blocking filter and is connected to the cylindrical lens 22a (
24a, 24b...).

The filter 23 and the light-receiving medium 14 are located within the optically conjugate focal plane of the cylindrical lens 22c, and are located within the optically conjugate focal plane of the cylindrical lens 22c, and are located within the optically conjugate focal plane of the cylindrical lens 22c.
) and the light-receiving medium are at optically conjugate positions with respect to the spherical lens system 22b. In other words, with respect to the anamorphic lens system 22 composed of the cylindrical lenses 22a, 22c and the spherical lens system 22b, in the plane perpendicular to the arrangement direction of the heating resistors, the light reflecting layer (Fig. 1A) or the heating resistor (6a, 6b, .
. In the determined plane, the light-receiving medium 14 is located on the focal line plane of the anamorphic lens system 22. In FIG. 5, only the heating resistor portion of the light modulation element LM is shown.

In the above-described embodiments, the light modulation element is of a reflective type, and both the diverging light beam and the non-divergent light beam are reflected by the light reflecting layer or the resistor. FIG. 6 shows a case where both light beams pass through the light modulation element. The structure itself of the light modulation element shown in FIG. 6 is the same as that shown in FIG. 1(B), but the support 5',
The heating resistors (6B', 6b'...) and the insulating layer 3' are made of a transparent medium. In this case as well, extensive practical effects can be obtained using the optical system described above.

FIGS. 7(A) and 7(B) show the light modulation element L according to the present invention.
This is a diagram showing another embodiment of the light modulation device using M, and similarly to the optical system shown in FIG. 5, the arrangement of heating resistors 6a + 6b +... A linear image is formed in the direction. FIG. 7(5) is a developed view seen from a direction perpendicular to the line image. Figure 7 (I3) is a side view of the 7th country. The difference from the optical system shown in Figure 5 is that
The light beam emitted from the light source is condensed by the lens 20a, and a conjugate image of the light source is formed between the light modulation element LM and the lens 25 as shown in FIG. 7(3). As shown, a line image is formed in the vicinity of the heating resistor of the light modulation element LM by a line image forming optical system 20 which is a composite system of a lens 20a and an anamorphic lens 20b. Figure 7 (5
), heating resistors 6a, 6 are placed at the conjugate image position of the light source.
By arranging a rectangular light-shielding filter 23 having a long side in a direction perpendicular to the arrangement direction of b. passing around the light reflecting layer (Fig. 1A) or the heating resistor (6a,
6b, .

In this way, the configuration of the optical system as shown in FIG. 5 can be simplified.

FIG. 8 is a diagram showing an embodiment of a light modulation device for obtaining a color image to which a light modulation element according to the present invention is applied. The light source 19a is a red light emitting diode, 19b is a green light emitting diode, 19c is a blue light emitting diode, 26 is a dichroic mirror that transmits the red wavelength band and reflects the green wavelength band, 27 transmits light other than the blue wavelength band, A dichroic mirror that reflects the blue wavelength band), a light modulation element L-
The structure of the optical system is the same as that shown in FIG. 7 except that each light source is placed on the M heating resistor.

Using such a three-color light source and one light modulation element, it is possible to generate a color image on a light-receiving medium. FIG. 9 is a diagram showing one system of the color image generation system shown in FIG. 8. FIG.

..., 6e) shows the voltage pulse train input to V, i
.

V2i, ..., Vsi (i = 1 to 3) are voltage pulses applied to the heating resistors (6a, 6b, ... 6e), respectively, and 1 (-1 to 3) is the period of the voltage pulse. Show the number. FIG. 9(B) shows the current signal pulse input to the light emitting diode 19a, and the voltage pulse train V, , ,
V2. +... indicates that the light emitting diode 19a emits light during the period in which V51 is generated. FIG. 9 (O is a current signal pulse input to the light emitting diode 19b, and the voltage pulse train V12 + V22 g '-'.

This indicates that light is emitted during the period in which Vfi2 is generated. FIG. 9(D) similarly shows the voltage pulse train v13 + V23 +
”', within the period in which V53 occurs, light emitting diode 1
9c indicates that light is emitted. 9th country, (B), (C'
) and (c), the horizontal axis indicates time, and in the earlier time period (not shown), the above-mentioned signal pulses occur periodically. As shown in FIG. 8, when the light-receiving medium 14 moves in the direction of the arrow, red, green, and blue spots are formed on the surface of the light-receiving medium in the direction of the arrow, that is, in the direction of movement of the light-receiving medium. Color display can be performed by forming one pixel with these three spots. In the 9th study, voltage pulses were input to all heating resistors at the same time interval, but if you decide to generate a power pulse according to the image signal, you can create any color image. It becomes possible to generate the light on the light-receiving medium 14.

As described above, in the present invention, it is not necessary to have special polarization characteristics, and light sources with different wavelengths can be used.

FIG. 10 shows an application example of the device shown in FIG. 8, in which the color image shown in FIG. 8 can be scanned with a scanning spot over the entire surface of the stationary light-receiving medium 14 using a deflector 30. This is an example in which

If a photosensitive recording material such as a silver halide film is selected as the light-receiving medium, a digital color printer can be realized, or if a light-diffusing screen is selected as the light-receiving medium, a color display can be realized. In the present invention, the extinction ratio of the signal light (divergent light due to refractive index distribution) is high,
Since the divergence efficiency is high, the brightness of the imaged spot light on the light-receiving medium can be increased, making it possible to increase the brightness of the imaged spot light on the light-receiving medium.
Alternatively, a color display becomes possible. or,
Needless to say, digital printers and displays may be monochrome printers and monochrome displays with one light source as described above.

Note that in the embodiments shown in Figs. 5 to 10, divergent light due to refractive index distribution was used as the signal light, but as shown in Fig. 3 Φ), non-divergent light was used as the signal light. It goes without saying that it can be used, so I will omit it.

FIG. 11 is a diagram showing a further embodiment of a light modulation device to which the light modulation element according to the present invention is applied for obtaining a color image. In FIG. 11, a light source 31 is a general white light lamp such as a halogen lamp, a lens 32 is a condensing lens, and a lens 33 is a general white light lamp such as a halogen lamp.
34 is a collitter lens, 35 is a prism that causes chromatic dispersion, and 36 is a pinhole plate that limits the secondary light source image.
The converging lenses f40R, 40G, and 40B are heating resistors for generating red, green, and back scattered light, which are color signals, respectively, and voltage application means for independently generating voltage pulses corresponding to input signals. 41R, 41G, 4
Connected to 1B. Here, the details of the light modulation element are not shown to simplify the explanation, but the structure is the same as that shown in FIG. 2 except for the above-mentioned heating resistor section.

In the above example, the chromatic dispersion prism 35 and the lens 3
6, heating resistors 40R and 40G.

It becomes possible to form focused images of red, green, and blue light beams on 40B, respectively, and to modulate each color signal light according to the image signal.

Furthermore, in FIG. 11, instead of the lens 36, a cylindrical lens having a generatrix in the direction perpendicular to the plane of the paper is used,
The red, green, and blue light beams are each formed into linear images. At this time, linear beams of light corresponding to each color are formed side by side, with a little distance from each other. Therefore, by arranging a plurality of the heat generating resistors 40R, 40G, 40B'jfI:lY=t along the direction of the line image, a plurality of color pixel columns can be obtained. Furthermore, the first
Instead of the prism as the beam dispersion means in Figure 1,
The same effect can be achieved using a diffraction grating.

FIG. 12 is a further embodiment of a light modulation device to which the light modulation element of the present invention is applied, and is a diagram showing that in the present invention, there is no restriction on the direction of the light beam incident on the light modulation element. , No. 121 is a view seen from the direction in which the heating resistors are arranged, and FIG. 12 (03) is a view of No. 121 viewed from above. The components are the same as the light quality RtAI device shown in FIG. 5, but in the optical system shown in FIG. The central ray of the light beam incident on the light reflecting layer 2 (FIG. 1A) or the heating resistor layer 4 (FIG. 1B) at an angle of +/C is shown in FIG. In the optical system shown,
Similarly, the light flux incident on the light modulation element is transmitted through the light reflection layer 2 (first
(A) or parallel to the heating resistor layer 4 (FIG. 1B). In the light beam that has passed through the light modulation element, the non-divergent light beam is interrupted and the diverging light beam reaches the surface of the light-receiving medium, as in the case shown in FIG.

FIGS. 13 and 14 are views showing other modified embodiments of the light modulation element shown in FIG. 1, in which heating resistors (6a, 6b) are provided on the inner surface of the transparent adhesive plate 1a.

By providing a means 1c for restricting the shape of the refractive index distribution of the solid layer that receives heat from the heat generating resistor, the refractive index distribution generated in a certain heat generating resistor is It is designed so that it stays in the vicinity of . By doing so, it is possible to form a high-contrast image on the surface of the light-receiving medium without causing the refractive index distributions generated in each heating resistor to interfere with each other. Further, the shape of the solid layer can be set to a desired shape depending on the shape of the inner surface of the transparent protection plate. This allows the refractive index distribution line generated in the solid layer to be freely changed depending on the shape of the inner surface of the transparent protection plate. Furthermore, by selecting a transparent protective plate that has a small refractive index change due to heat, it is possible to increase the difference in refractive index that occurs between the solid layer and the transparent protective plate when heat is applied to the solid layer. . This results in an interface having a large refractive index difference, and therefore it is possible to obtain greater light divergence at this interface.

In this case, by selecting a material whose refractive index is close to the refractive index of the material of the transparent protective plate 1a and the refractive index of the solid in the solid thin layer lb when no heat is applied, the internal shape of the transparent protective plate IC can be adjusted. It is possible to prevent light scattering due to The internal shape 1c described above can be a divine shape such as a spherical surface or a cylindrical surface.

FIG. 14 (d) is a diagram showing that the heat generating resistor layer 4 is composed of a spherical or cylindrical surface. With this configuration, the light flux that is not diverged by the refractive index distribution can be transmitted to the heat generating resistor layer 4. A light shielding member is provided at the image formation position.By using such a light modulation element, the lens 13a shown in FIG. 3 can be omitted. .

Note that the cross section of the light modulation element shown in FIGS. 13 and 14 is as follows:
It is viewed from the same direction as the cross-sectional view shown in FIG. 4CB), and the light beam incident on the means is incident at an angle forming the front side with respect to the plane of the paper.

Figure 15 shows a light modulation element that makes it possible to generate a refractive index distribution in a matrix. Figure 15 (G) is a side view of the light modulation element, and Figure 15 (B) is a light modulation element. This figure shows the arrangement of the heating resistor layers when the element is viewed from the front, that is, when the 15th country is viewed from the A1 direction. Figure 15 (
In 5), the transparent protection plate 1as solid thin layer 1b and the support 5 are the same as the light modulation element shown in FIG.

3a and 3b are thermally conductive insulating layers, and 42 and 43 are heating resistor layers in which a plurality of linear heating resistors are arranged in parallel at the same interval, as shown in Figure 15 CB). Similarly, the resistors (42a to 421) of the heat generating resistor layer 42 and the resistors (43a to 43k) of the heat generating resistor layer 43 are provided so as to form an angle α. In the light modulation element shown in FIG.
When a voltage is applied to any of the intersecting heating resistors, the design is such that a refractive index distribution occurs in the intersecting region. For example, if voltage is now being applied to 42d, 43c, and 43e, the intersection area P painted in black,
A refractive index distribution occurs at P2. Therefore, if you want to obtain a pattern with a two-dimensional refractive index distribution, for example, first apply a voltage only to 42a of the heating resistors 42a to 42e, and select the desired one from among the heating resistors that intersect with 4.2a. Then, a voltage is applied only to 42b, and a desired heating resistor is selected from among the heating resistors that intersect with 42b, and a voltage is applied thereto. By performing such operations 42a to 421, a two-dimensional pattern can be obtained.

FIG. 16 shows an embodiment of a light modulation device using the light modulation element shown in FIG. 15.

A light modulation element 45 capable of generating a refractive index distribution in a two-dimensional pattern is irradiated with a light beam from a light beam generating means 44 consisting of a light source 44a and a collimator lens 44b. The light beam that is not diverged by the refractive index distribution passes through the lens 4.
The light is collected by a lens 46 and blocked by a light blocking filter 47 provided at the focal plane of a lens 46. Since the light beam scattering position of the light modulation element 45 is arranged to almost coincide with the other focal plane of the lens 46, the light beam diverged by the light modulation element 45 becomes a substantially parallel light beam at the lens 46, and the light beam diverges from the lens 49.
The image is formed on the surface of the photosensitive medium 50 to form a two-dimensional image according to the pattern of the refractive index distribution. If a deflection mirror 48 is disposed between the lens 46 and the lens 49 to deflect the diverging light beam, the two-dimensional scanning image described above can be obtained on the photoreceptor surface 50. For example, if the light modulation element that generates the refractive index distribution two-dimensionally is designed to form various character patterns using the refractive index distribution, it can be realized as a printer-like terminal such as a word processor. Intermittent rotation of the deflection mirror is preferable because the optical modulation element 45 does not simultaneously produce a refractive index distribution over the entire surface.

It goes without saying that even among light modulation elements capable of forming a two-dimensional pattern, a transmitted light type light modulation element as shown in FIG. 6 can be obtained.

In the above embodiment, an example was described in which a refractive index distribution was formed using a heating resistor, but in order to obtain a refractive index distribution,
It is also possible to obtain heat by scanning a light beam and converting the scanned beam into heat. FIG. 17 shows an embodiment in which a refractive index distribution is formed by scanning a light beam, and the light modulation element LM consists of a transparent protection plate 51a, a solid thin layer 51b, a light reflection layer 52, and a thermally conductive insulator. It is formed of a layer 53 and a transparent support 54, and the support 54 has a heat absorption layer 5.
5 is provided.

56 is a self-modulating semiconductor laser;
The light flux from 6 is turned into a parallel beam by a collimator lens 57, and is imaged onto the heat absorption layer 55 by a scanning condenser lens 59 via a galvanometer mirror 58. This heat absorption layer 55 is made of a material that particularly absorbs the light beam of the wavelength from the semiconductor laser 56, and therefore, the heat absorption layer 55
The luminous flux passing through 5 becomes almost zero. Said galvano mirror
The scanning optical system is set so that when 58 is rotated around rotation axis 9, the light beam spot moves along the absorption layer 55 in the direction of arrow A2. In the region of the absorption layer 55 where the beam spot by the semiconductor laser 56 is formed, the light beam is converted into heat, forming a refractive index distribution in the solid thin layer 52 via the insulating layer 53. Therefore, by turning on and off the beam emitted from the semiconductor laser as the galvanometer mirror 580 rotates, a refractive index distribution can be formed at a desired position. The optical system for projecting the light beam diverging due to the refractive index distribution and guiding the diverging light to the light-receiving medium includes the above-mentioned reflective type optical system, including the optical system shown in FIG. It goes without saying that all of them can be used, so the explanation will be omitted here.Also, by providing the heat absorption layer 55 on the entire surface and making the scanning optical system for irradiating the light beam onto the absorption layer a two-dimensional scanning optical system. , a light modulation element with a refractive index distribution having the two-dimensional pattern shown in FIG. 15 can be obtained.

As described above, compared to conventional modulation devices, in the modulation optical system according to the present invention, (1) the divergence angle of the light beam diverged by the refractive index distribution is achieved by selecting a solid material having a thermal effect; can be taken relatively large, so when separating divergent light and non-divergent light,
It can be separated efficiently, so the efficiency of using the luminous flux is high, and the S/M ratio is also high.

(2) In the case of divergence due to a refractive index distribution, a constant scattering property is obtained regardless of the angle of incidence of the light beam incident on the same body with a refractive index distribution, so restrictions are imposed on the arrangement of the optical system. Never.

(3) When using an electro-optic crystal, one light modulation can be performed with two electrodes, whereas when using divergence by refractive index distribution as in the present application, one light modulation can be performed with one electrode. Therefore, high-density modulation per unit area is possible, and high-quality display or recording is possible.

(4) When the luminous flux is diverged by the refractive index distribution, there is no need to particularly polarize the incident luminous flux, and the same effect can be obtained using a general light source other than a laser, so the device can be formed at low cost. .

(5) The heating resistor ° for generating refractive index distribution is ■・
It can be easily formed using the C pattern manufacturing method,
A high-density arrangement of 100 or more lines per layer is easily possible, and therefore high-quality images can be achieved. Furthermore, by using the I-C pattern manufacturing method, it is possible to arrange 1,000 to 1000 heating resistors on the micron order.
It is easy to line up the number of heating resistors necessary to scan a line, and therefore one line can be scanned at the same time, resulting in excellent effects such as speeding up image recording and image display. It is something that you have.

3(B) and 3(B) are diagrams showing an embodiment of the light modulation device using the light modulation element according to the present invention, and FIG. 5 is a diagram showing a preferred embodiment of illuminating a light modulation element according to the present invention, FIG. 5 is a diagram showing another embodiment of a light modulation device using the light modulation element according to the present invention, and FIG. Figures 7(A) and 7(F)) showing other embodiments of the light modulation element according to the present invention are diagrams showing other embodiments of the light modulation device using the light modulation element according to the present invention. ,
8 and 9 are diagrams showing an embodiment of a color image forming light modulation device using the light modulation element according to the present invention, and FIGS. 10 and 11 are diagrams showing an example of a color image forming light modulation device using the light modulation element according to the present invention. FIG. 12 is a diagram showing another embodiment ψU of a color image forming light modulation device; FIG. Figure 14 and 1
Figures 5 and 5 (B) each show an embodiment of the light modulation element according to the present invention, and Figure 16 shows a light modulation device formed using the light modulation element shown in Figure 15 and (B). FIG. 17 is a diagram showing another embodiment of the light modulation device using the light modulation element according to the present invention.

1 &...Transparent retention plate 1b...Polymer thermal effect medium 2...Light reflecting layer 3...Insulating layer 4...Insulating layer 5...Supports 6a, 6b, 6c, 6d- Heat generating resistor L-M...
・Light modulation element 7...Refractive index distribution 11...Non-divergent light flux 12...Divergent light flux 14...Light-receiving medium 15a...Shading filter output 7@person Canon Corporation 6C6b 6L Tsumugi 15en (A ) Figure 75 (B)

Claims (1)

[Claims] (1) A means for generating heat in response to an input signal, and a solid polymer medium that receives the heat from the heat generating means and generates a refractive index distribution (7i). A light modulation element characterized by transforming the wavefront of a beam of light.