JPS5968723A - Optical modulating element - Google Patents

Abstract

PURPOSE:To improve the utilization rate of a luminous flux and the S/N ratio, by selecting a liquid having a thermal effect and setting the divergent angle of the luminous flux to a relatively large value. CONSTITUTION:This optical modulating element is composed of a transparent protective board 1, liquid thin layer 2, insulating layer 3 having a heat conductivity, exothermic resistance body layer in which exothermic resistance bodies are arranged, supporting body 5 for the insulating layer 3 and exothermic resistance body, etc. When the exothermic resistance body emits heat, this heat is transmitted to the liquid thin layer 2 through the insulating layer 3 and produces a temperature distribution in the liquid thin layer 2 and forms a refractive index distribution. By the refractive index distribution, the liquid surface of an incident luminous flux is deformed and optical modulation is performed. When such an arrangement is used, a desired characteristic is obtained even when the incident luminous flux is used for either transmission or reflection and, therefore, the utilization rate and S/N ratio of a luminous flux can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a force-first modulation element suitable for optical recording devices, optical display devices, and the like.

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. It has been shown that modulation is performed by diffracting a light beam incident on a portion of the structure where the refractive index changes. However, electro-optic crystals are expensive, and when used, the light beam incident on the crystal (1) must have predetermined polarization characteristics.

In addition, when performing the above-mentioned modulation, in order to completely reflect the light beam at the electric field generation part inside the optical crystal material and improve the diffraction efficiency, there is a restriction that the light beam is incident on the electrode as far 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,
Introduced in "Light is deflected due to refractive index change due to heat" (Nikkei Electronics August 16, 1982 issue) or "Response speed of To glass waveguide optical switch" (1988 IEICE General Conference) There is.

In these examples, TlO2 crystals or glass made using an ion exchange method are used as the heat effect medium. Generally, the temperature dependence of the refractive index of a solid is small, and in order to obtain the desired deflection characteristics, a high voltage is required as the voltage applied between the electrodes or the voltage applied to the heater resistor (2). Furthermore, in order to obtain efficient deflection characteristics on each of the above-mentioned sides, 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 place the electrode or heater as close as possible to the surface of the electrode or heater. It is necessary to propagate the light beam as parallel as possible.

SUMMARY OF THE INVENTION An object of the present invention is to provide a light modulation element that improves the above-mentioned conventional drawbacks.

In the present invention, the above object is achieved by using a liquid whose refractive index is highly dependent on temperature as a thermal effect medium that causes a change in refractive index (by thermal effect). That is, by applying heat to a liquid in accordance with an input signal, a refractive index distribution is generated in the liquid, a light beam is made to enter the liquid having this refractive index distribution, and the incident light beam is changed according to the refractive index distribution. Modulation is performed by deforming the wavefront.

(3) In the present invention, since a liquid is used as the thermal effect medium, the wavefront of the incident light beam can be sufficiently transformed without using a high voltage as in the conventional case. Since there is no need to limit the propagation position of the light flux, that is, the position of the thermal effect medium through which the light flux passes, the desired characteristics can be obtained whether the light flux incident on the element is transmitted or reflected, and the range of application is wide. It has the effect of increasing Hereinafter, the present invention will be explained in detail using the drawings.

FIG. 1 is a diagram showing an embodiment of a light modulation element according to the present invention. In Fig. 1, 1 is a transparent protective plate, 2 is a thin liquid layer, 3 is a thermally conductive insulating layer, 4 is 6a, 6b, 5C,
6d... is a heating resistor layer in which heating resistors are arranged, 5 is an insulating layer 3 and heating resistors 6a, 6b, 60,
6 (support for 1...).

When the heating resistor generates heat, this heat is transferred to the insulating layer 3.
is transmitted to the thin liquid layer 2, producing a temperature distribution within the thin liquid layer and forming a refractive index distribution. For example, as shown in FIG. 1, when the heating resistor 6b is selected and generates heat, this heat is transferred to the liquid thin layer 2 via the insulating layer 3 adjacent to the resistor (4) and the resistor 6b. The liquid in the region of the thin liquid layer 2 facing the is heated to form a refractive index distribution 7 in this region. This refractive index distribution 7 disappears after a predetermined period of time as the liquid in this region cools. One cycle from the formation of this refractive index distribution to its extinction is a very short time, and K
It is possible to perform on the order of Hz.

The heating resistors described above are formed on the support 5 using the manufacturing technique (1) and (C), and the spacing between adjacent heating resistors is on the order of mμ.

The liquid used in the light modulation element of the present invention may be water, alcohol, or other liquids. The temperature dependence of the refractive index of this liquid is -1, OXl 0-' for water, and -4,0x10-4 for ethyl alcohol. In contrast, in the conventional thermal effect crystal described above, TlO2
is -7,2x10-' for extraordinary light, -4°2x10-5 for ordinary light, PbM004 is -4,1x10-5 for extraordinary light, -7°2x for ordinary light
10"-5, LiN'bo, against extraordinary light 5) 5゜3X10, 0.5SX10 against ordinary light
Both the liquid and the liquid show values that are one order of magnitude smaller than those of the liquid.

Note that this data is a value for a luminous flux with a wavelength of 6 S 2.8 nm.

In this way, using a liquid as a medium for converting the wavefront of incident light eliminates the need to pay special attention to polarization, unlike conventional crystals. Furthermore, the absolute value of the temperature dependence (static) of the refractive index is larger than that of conventional crystals, and the phase difference between the modulated light beam and the unmodulated light beam can be increased. This eliminates the need for the light beam to propagate parallel to the electrode surface or the heater surface, unlike the conventional example. In other words, it can be used with normal incidence to the heater surface or with other angles of incidence.)
, it is possible to eliminate restrictions on arrangement when assembling modulation elements into a device.

FIG. 2 is a schematic perspective view showing the configuration of the light modulation element shown in FIG. 1, and numbered 1 to 6 are the same as shown in FIG. 1. 8 is a conductive wire, which is connected to the drive voltage of each side of the machine that can independently drive the heating resistors (6a, 61), etc., while the other end of the heating resistor is grounded. Or they are set to a common voltage. From the conductive wire 8, the heating resistor 613. ．． When a voltage signal is applied to each of the heating resistors 6b, . . . , a refractive index distribution is generated in the liquid thin 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.

FIG. 3(A) shows the light modulation element based on the refractive index distribution, M
FIG. 2 is a diagram showing an example of a light modulation device using a refractive index distribution, and is an example in which a light beam whose wavefront is modified by a refractive index distribution is used as information light. A light beam 1o is incident on the light modulation element M, and the heating resistor (6a) is incident on the light modulation element M.

6b,...), any heating resistor 6c has a voltage V
1, a refractive index distribution 7 occurs, and the light beam incident on the heating resistor 6c becomes the light beam 1 with a deformed wavefront.
It becomes 2 and fires. It is specularly reflected on the surface of the heating resistor,
The light beam 11 whose wavefront is not deformed by the refractive index distribution 7 is
An image is formed by the lens 13a, and the light is blocked by a light-shielding filter (7) placed at the image-forming position. The light beam 12 whose wavefront has been deformed is partially blocked by the light blocking filter 15a, but the size of the light blocking filter 15a is set to the minimum size that blocks the imaging spot of the light beam 11 whose wavefront is not deformed. Accordingly, 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 compared to the diffraction angle using the electro-optic crystal described above. Therefore, even if a light shielding filter 15a of the same size is used, the proportion of divergent light that is shielded is very small in the present invention.

As described above, by applying the voltage pulse 1 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 repeatedly generated or eliminated in response.

In that case, a blinking light spot is generated on the light receiving medium 14. Heat generation (8) is generated by the lens 13a. By creating a conjugate relationship between a point on the resistor and a point on the light receiving medium 14, a refractive index distribution is generated near the heat generating resistor (6a, 6b, . . . ). An image of the portion can be formed as a spot on the light-receiving medium 14.

FIG. 3(B) is a diagram showing an embodiment of a light modulation device using the light modulation element LM, 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 position where the light beam 11 that is not modulated by the light modulation element M is focused by the lens 13a is as follows.
A light shielding plate 15b is provided. 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 M.

As described above, most of the divergent light due to the refractive index distribution is blocked by the light blocking filter 151), and only the light beam 11 whose wavefront is not deformed passes through the light blocking filter 151). Then, the imaging spot or the light-shielding filter 151) formed by the lens 13a and the light-receiving medium surface 14
By arranging the lens 13b that has a conjugate relationship (9), the light-receiving medium surface 1
4, a flashing light spot occurs.

Figure 4 shows a light modulation element, M
FIG. 2 is a diagram showing the state of the light flux incident on the thermal resistor as seen from a direction perpendicular to the arrangement direction of the thermal resistors. Regarding the refractive index distribution, the gradient of the refractive index of the culm dust near the heating resistor is steep, and the divergence efficiency is highest when the light beam 16 is incident thereon in a concentrated manner. Also, depending on the flatness or roughness of the surface of the support 5, the heating resistor (6&, 6b, . . . ), or the insulating layer 3,
Regarding light beams other than the diverging light due to the refractive index distribution, the light shielding efficiency of the light shielding filter 15 is poor, and the light beams are irradiated onto the light receiving medium 14 as noise light. This noise light is irradiated onto the light-receiving medium 14 regardless of the input signal voltage pulse (1) applied to the conductive line (8), resulting in a decrease in contrast. In order to eliminate such inconveniences, (10) it is desirable to converge the incident light beam 16 linearly near the heating resistor as shown in FIG. 4(A).

Reference numeral 17 is a specularly reflected light beam (light that is not subject to divergence due to the refractive index distribution) of the incident light beam 16, and 18 indicated by a broken line is a divergent light beam due to the refractive index distribution. Figure 4(B) is the same as Figure 4(A).
), 17 is a specularly reflected light beam of the incident light beam 16, 18 is a diverging light beam due to the refractive index distribution generated near the heating resistor 6C to which the image signal is input, The specularly reflected light beam 17 is scattered in different directions.

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 light modulating element and M heating resistors (61L, 6b, . . . )
A linear image is formed in the direction in which the images are arranged. A component of this linearly formed light beam (11) in a plane perpendicular to the arrangement direction of the heating resistors is in a parallel light beam state.

Therefore, the light beam 17 that is not diverged by the heating resistor enters the positive cylindrical lens 22a through a triangular prism-shaped optical path. Cylindrical lens 221! L has its generatrix in the direction in which the heating resistors are arranged, and is provided so that its focal line coincides with the position of the heating resistors. Therefore, the luminous flux 1
After passing through the cylindrical lens 22a, the light beam 7 enters the afocal light beam and the spherical lens 221).

The light beam 17 is then focused by a spherical lens 221) on the focal plane of this lens. At this focal plane, there is a rectangular filter 23 having a size large enough to block the light beam 17.
Therefore, the light beam that has not been diverged by the heating resistor is blocked by the filter 23. On the other hand, the light beam 18 diverged by the heat generating resistor is converted into parallel light by the cylindrical lens 22a, so that only the light beam within a plane perpendicular to the arrangement direction of the heat generating resistors becomes parallel light, and furthermore, the light beam 18 diverged by the spherical lens 221) is connected to the rectangular filter. A linear image is formed near 23. Therefore, a part of the diverging light flux 18 is blocked by this rectangular filter 23, but most of the light flux is not blocked by this light blocking filter, and is transmitted through the positive cylindrical lens 222L, which has a generatrix in the same direction as the cylindrical lens 222L. The light enters the lens 22Q and is formed as a point image (24a, 241), etc. on the light receiving medium 14. The filter 23 and the light-receiving medium 14 are located within the optically conjugate focal plane of the cylindrical lens 220, and the heating resistor and the light-receiving medium are located within the spherical lens system 2.
21) at an optically conjugate position. In other words, regarding the anamorphic lens system 22 composed of the cylindrical lenses 22a, 220 and the spherical lens system 22kl, the heating resistors (" +6b+...) and the light-receiving medium 14 are arranged in an optically conjugate focal plane, and
The light-receiving medium 14 is located on the focal line plane of the anamorphic lens system 22 in a plane defined by the optical axis of the anamorphic lens system 22 and the arrangement direction of the heating resistors (03). In addition, in FIG. 5, the light modulation element,
M shows only the part of the heating resistor.

In the above-mentioned embodiments, the heating resistor is composed of a reflective member, and both the diverging light flux and the light flux subject to divergence,
Although the case where each light beam is reflected by a resistor is shown, FIG. 6 shows the case where any light beam passes through a light modulation element. 6th
The structure itself of the light modulation element shown in the figure is the same as that shown in FIG.
) and the insulating layer 3' are made of a transparent medium. In this case as well, sufficient practical effects can be obtained using the optical system described above.

FIGS. 7(A) and 7(B) are diagrams showing other embodiments of the optical modulation device using the optical modulation element M according to the present invention.
Similar to the optical system shown in the figure, a linear image is formed in the arrangement direction of the heat generating resistors 6a, 6b, . . . in the light modulation element M. FIG. 7(A) is a developed view seen from the direction perpendicular to the line image. Figure 7 (B) is shown in Figure 7 (
It is a side view of A). The difference from the optical system shown in FIG. 5 is that the light beam emitted from the light source is condensed by a lens 20a, and as shown in FIG. As shown in FIG. 7(B), a line image is formed in the vicinity of the heating resistor of the light modulation elements (1)...M by the line image forming optical system 20, which is a composite system of the lens 20a and the anamorphic lens 2011. It is to form. In FIG. 7(A), by arranging a rectangular light shielding filter 23 having long sides in a direction perpendicular to the arrangement direction of the heat generating resistors 6a, 6b, etc. at the conjugate image position of the light source, the refractive index distribution is changed. The luminous flux that is not diverged by the refractive index distribution is blocked, and the luminous flux that is diverged by the refractive index distribution passes around the light shielding filter 23 and passes through the heating resistors (6a, 6b, . . .
...) enters the lens 25 that keeps the light-receiving medium 14 in a conjugate position, and the image is formed on the light-receiving medium 14) 24a, 24
1) Forming . . . By doing this, the configuration of the optical system as shown in FIG. 5 can be simplified.

(15) FIG. 8 is a diagram showing an embodiment of a light modulation device for obtaining a color image to which the light modulation element according to the present invention is applied. The light source 19a is a red light emitting diode, 19'b 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, It is a dichroic mirror that reflects the blue wavelength band, and a light modulation element.
The optical system has the same configuration as the optical system shown in FIG. 7 except that the light beams from each light source are directed onto the heating resistor M. Using this various trichromatic light source and one light modulating element, it is possible to generate a color image on the receiving medium. FIG. 9 is a diagram showing one method of the color image generation system shown in FIG.・,6e) Indicates the voltage pulser ('' input to), ■11v21...
V51 (i=1 to 3) are the heating resistors (5a
, 6b, ... is a voltage pulse applied to 6ri, and 1
(-1 to 3) indicate the number of the period. Figure 9 (B)
is a current signal pulse input to the light emitting diode (16) diode 19a, and indicates that the light emitting diode 19a emits light during the period in which the voltage pulse train (11) #v2+1...v51 is generated.

FIG. 9(C) shows a current signal pulse input to the light emitting diode 191), and the voltage pulse train Vj2+v221
...indicates that light is emitted during the period in which 1v52 occurs.

FIG. 9(D) similarly shows the voltage pulse train v1. ．． v2. ．．
・、.

This indicates that the light emitting diode 190 emits light during the period in which vss occurs. Figure 9 (A) l (B), (C
), (D), the horizontal axis indicates time, and the above-mentioned signal pulses are generated periodically in a previous time period (not shown). 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 FIG. 9(A), voltage pulses were input to all heating resistors at the same time interval, but if you decide to generate power pulses according to the image signal, any color image ( 17) It becomes possible to generate 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. Alternatively, if a light diffusion 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, and
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.
1 or a color display becomes possible. Needless to say, digital printers and displays may be monochrome printers (18) and monochrome displays with one light source as described above.

In addition, in the examples 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(B), non-divergent light was used as the signal light. It goes without saying that it can be done, 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 52 is a condenser lens, and a lens 33 is a condensing lens.
34 is a collimator lens; 35 is a prism that causes chromatic dispersion; 36 is a pinhole plate that limits the secondary light source image;
is a converging lens; 4OR, 40G, and 40B are heating resistors for generating red, green, and blue scattered light, which are color signals, respectively; and voltage application that independently generates voltage pulses corresponding to input signals. Means 41R, 41G, 4
Connected to 1B.

Here, the details of the light modulation element are not shown to simplify the explanation, but the structure other than the heating resistor section (19) is the same as that shown in FIG. 2.

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

A focused image of a red light beam, a green light beam, and a blue light beam are respectively formed on the 40B, and each color -
It becomes possible to modulate signal light.

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 making the heating resistors 40R, 40G, and 40B into one unit and arranging a plurality of these units along the direction of the line image, a plurality of color pixel rows can be obtained. Incidentally, the same effect can be obtained by using a diffraction grating instead of the prism as the beam dispersion means in FIG. 11.

FIG. 12 is a further embodiment of the light modulation device (20) to which the light modulation element of the present invention is applied, and shows that in the present invention, there is no restriction on the direction of the light beam incident on the light modulation element. FIG. 12(A) is a view seen from the arrangement direction of the heating resistors, and FIG. 12(B) is a view of FIG. 12(A) viewed from above. The constituent members are the same as the light modulation device shown in FIG. 5, but in the optical system shown in FIG. In contrast, in the optical system shown in FIG. 12, the light beam incident on the light modulation element is incident on the heating resistor layer 4 at an angle of
The light is incident parallel to the heating resistor layer 4. In the light beam that has passed through the light modulation element, the non-divergent light beam is blocked and the diverging light beam reaches the surface of the light-receiving medium, as in the case shown in FIG.

13 and 14 are views showing other modified embodiments of the light modulation element shown in FIG.
If a stone means 1a is provided to restrict the shape of the refractive index distribution of the liquid layer that receives heat from the heating resistor ("+6b+...) and adjusts the refractive index distribution, (21), with a certain heating resistor. The generated refractive index distribution is made to stay near the heating resistor.By doing so, the refractive index distribution generated in each heating resistor does not interfere with each other, and images with good contrast can be obtained. can be formed on the surface of the light-receiving medium.Also, the shape of the liquid layer can be formed into a desired shape depending on the shape of the inner surface of this transparent protective plate. It is possible to freely change the refractive index distribution curve generated inside the transparent protective plate by changing the shape of the inner surface of the transparent protective plate.Furthermore, by selecting a transparent protective plate that has a small change in refractive index due to heat, When heat is applied to the liquid layer, the difference in refractive index that occurs between the liquid layer and the transparent protection plate can be increased.This means that an interface with a large difference in refractive index is created.
Therefore, it is possible to obtain greater light divergence at this interface.

In this case, choose a material whose refractive index is close to the refractive index of the material of the transparent protection plate 1 and the refractive index of the liquid in the thin liquid layer 2 when no heat is applied), (22) Transparent. It is possible to prevent light scattering due to the internal shape 1a of the protection plate. The internal shape 1a described above can have a spherical surface, a cylindrical surface, or any other shape.

FIG. 14 is a diagram showing that the heating resistor layer 4 has a spherical or cylindrical surface.

By configuring as above, it is possible to converge the light beam that is not diverged by the refractive index distribution after being reflected by the heating resistor, and a light shielding member is provided at the imaging position. By using such a light modulation element, it is possible to omit the lens 13a shown in FIG. 3.

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 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.

Fig. 15 shows a light modulation element that makes it possible to generate a refractive index distribution in a matrix. Fig. 15 (A) is a side view of the light modulation element, and Fig. 15 (B) is a (26 ) This figure shows the arrangement of the heating resistor layers when the light modulation element is viewed from the front, that is, when viewed from the direction A in FIG. 15(A). Figure 15 (A) In K, transparent protection plate 1
, the thin liquid layer 2 and the support 5 are the same as the light modulation element shown in FIG. 5a.

5'b is a thermally conductive insulating layer, and 42 and 43 are heating resistor layers each having a plurality of linear heating resistors arranged in parallel at the same interval. As shown, the resistors (42a to 421) of the heat generating resistor layer 42 and the resistors (43a to 45k) of the heat generating resistor layer 43 are provided to form an angle α. The light modulation element shown in FIG. 15 is designed so that when a voltage is applied to any of the intersecting heating resistors, a refractive index distribution occurs in the intersecting region. For example, if voltage is applied to 42(l, 4'5Q, and 45@), the intersection area P1.P painted black
, a refractive index distribution occurs. Therefore, if you want to obtain a pattern with a two-dimensional refractive index distribution, for example, first apply a voltage only to 42 & of the heating resistors 421L to 421, and then υ Select the desired heating resistor and apply voltage, then 4
A voltage is applied only to 2b, and a desired heating resistor is selected from among the heating resistors that intersect the same <42b, and a voltage is applied thereto. A two-dimensional pattern can be obtained by performing this external operation in steps 42a to 421.

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 constituted by a light source 44 & collimator lens 441). The light beam that is not diverged by the refractive index distribution is converged by the lens 46 and blocked by a light shielding filter 47 provided at the focal plane of the 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 angle 46. Nasi, lens 4
9 forms an image on the multi-photosensitive medium surface 50 to form a two-dimensional image according to the generation pattern of refractive index distribution (2).Lens 46 and lens 4
If a deflection mirror 48 is disposed between the mirrors 9 and 9 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. The rotation of the deflection mirror is controlled by the light modulation element 45.
However, intermittent rotation is desirable because a refractive index distribution does not occur over the entire surface at the same time.

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 it by scanning a light beam and converting the scanned beam into heat (26). FIG. 17 shows an embodiment in which a refractive index distribution is formed by scanning a light beam, and the light modulation element LM includes a transparent protection plate 51, a thin liquid layer 52, and a thermally conductive insulating layer 53.
and a transparent support 54, the support 54
A heat absorbing layer 55 is provided. Reference numeral 56 denotes a self-modulating semiconductor laser, and the light beam from the laser 56 is converted into a parallel beam by a collimator lens 57, and is imaged onto the heat absorption layer 55 by a scanning condensing lens 59 via a galvanometer mirror 58. Ru. 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 light flux passing through the absorption layer 55 is approximately zero. The scanning optical system is set in such a way that when the galvanometer mirror 58 is rotated around the rotation axis, the light beam spot moves in the direction of arrow A2 along the absorption layer 55. Then, 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, and is bent (27
) form a refractive index distribution. Therefore, by turning on and off the beam emitted from the semiconductor laser as the galvanomirror 58 rotates, a refractive index distribution can be formed at a desired position. Incidentally, 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 is the fifth optical system.
It goes without saying that all of the above-mentioned reflective type optical systems can be used, including the optical system shown in the figure, so their explanation will be omitted here.

Furthermore, by providing the heat absorption layer 55 on the entire surface and using a two-dimensional scanning optical system as a scanning optical system that irradiates the absorption layer with a light beam, a refractive index distribution having the two-dimensional pattern shown in FIG. 15 can be obtained. It is possible to obtain a light modulation element according to the method.

As described above, compared to conventional modulation devices, in the modulation optical system according to the present invention, (1) by selecting a liquid having a thermal effect, the divergence angle of the light beam diverged by the refractive index distribution; Since υ can be taken relatively large, when separating divergent light and non-divergent light,
Since the separation amount (28) can be efficiently achieved, the efficiency of using the luminous flux is high, and the S/N ratio is also high.

(2) In the case of divergence due to a refractive index distribution, constant scattering characteristics are obtained regardless of the angle of incidence of the light beam incident on a liquid with a refractive index distribution, so there are no restrictions on the arrangement of the optical system. I can't get caught.

(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 υ 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, making the device inexpensive. Can be formed.

(5) The heating resistor for generating the refractive index distribution is (29
) It can be easily formed using the C pattern manufacturing method, and a high-density arrangement of 100 or more lines per battle is easily possible, thus making it possible to improve the quality of the image. Further engineering/
Using the C pattern manufacturing method, it is possible to arrange 1,000 to 10,000 heating resistors on the micron order, and it is easy to arrange the heating resistors in the number of dots required for scanning one line. Since one line can be scanned at the same time, it has excellent effects such as speeding up image recording and image display.

[Brief explanation of the drawing]

1 and 2 are diagrams showing an embodiment of the light modulation element according to the present invention, and FIGS. 3(A) and 3(B) are diagrams showing a light modulation device using the light modulation element according to the present invention, respectively. Figures 4(A) and 4(B) are diagrams showing a preferred embodiment of illuminating a light modulation element according to the present invention, and Figure 5 is a diagram showing a preferred embodiment of illuminating a light modulation element according to the present invention. A diagram showing another embodiment of the light modulation device, FIG. 6 is a diagram showing another embodiment of the light modulation element according to the present invention (30), and FIG. 7(A)
(B) are each photochange v! according to the present invention. FIGS. 8 and 9 are diagrams showing another embodiment of a light modulation device using four elements, and FIGS. 10 and 11 are diagrams showing other embodiments of a color image forming light modulation device using the light modulation element according to the present invention, and FIG. Figures 13, 14, and 15 (A) (B) showing other examples of the optical modulation device used;
) are diagrams showing one embodiment of the light modulation element according to the present invention, and FIG. 16 shows an embodiment of the light modulation device formed using the light modulation elements shown in FIGS. 15(A) and (B). Figure shown, 1st
FIG. 7 is a diagram showing another embodiment of the light modulation device using the light modulation element according to the present invention. 1...Transparent protective plate 2...Liquid thin layer 3...Insulating layer 4...Heating resistor layer 5...Support (31) 6a, 5b, 5c, 婬...Heating resistor M...Light modulation element 7...Refractive index distribution 11...Non-diverging light flux 12...Divergent light flux 14...Light-receiving medium 151L...Light-shielding filter Applicant: Canon Corporation (32) ( \ 136- 6C6b 6α 42g 42A4;'t 42j4vo42zContinued from page 10 Author: Masayuki Usui, Canon Co., Ltd., 3-30-2 Shimomaruko, Ota-ku, Tokyo Author: Atsushi Someya Atsushi Shimomaruko, Ota-ku, Tokyo 3-30-2 Canon Co., Ltd.

Claims (1)

[Claims] (1) A means for generating heat in response to an input signal; a liquid medium receiving the heat from the heat generating means and generating a refractive index distribution;
A light modulation element characterized in that the wavefront of multiple light beams is modified by the refractive index distribution in the liquid medium.