JPS6238431A - Optical modulation method - Google Patents

Abstract

PURPOSE:To attain farther rapid optical modulation by cooling a heat sensitive medium at the driving of an element. CONSTITUTION:When a switch 6b is closed, electric power is supplied from an external power supply 7 to a resistor heat generating layer 4b and heat generated on the layer 4b increases the temperature of a high molecular substance liquid layer 2. When the liquid temperature exceeds the critical temperature of the high molecular substance, the high molecular substance is crystalized in the liquid medium, the high molecular substance liquid layer 2 in the crystalized part is made uneven state and incident light 10b is remarkably dispersed in the layer 2. Therefore, a sharp repeating resonse can be held for a long period by interlocking cooling means 8, 9 with an optional means for detecting the temperature of the high molecular substance liquid and controlling the temperature of the high molecular substance solution at a temperature slightly lower than its critical temperature.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a novel light modulation method, and more specifically, to a novel light modulation method that utilizes a phase transition phenomenon of a polymeric substance due to a temperature change in a liquid polymeric substance. Regarding modulation methods.

(Prior Art) Conventionally, recording or displaying using light has been widely practiced. As a method for modulating light for this purpose, for example, Japanese Patent Application Laid-Open No. 56-5523 discloses that the electric field distribution within the crystal having an electrochemical effect is changed, and the refractive index within the crystal that occurs due to this electric field distribution is disclosed. It has been shown that light modulation is achieved by diffracting the light incident on the part where the change occurs.

On the other hand, modulation of light using refractive index distribution due to thermal effects is attracting attention. Regarding light modulation using the refractive index distribution caused by this thermal effect, see ``Light is deflected by a change in the refractive index due to heat.
(August 16, 1982 issue) or ``Response Speed of TO Glass Waveguide Optical Switch'' (IEICE General Conference of the Institute of Electronics and Communication Engineers, 1985).

Furthermore, as a method for solving the various drawbacks of the conventional light modulation methods as described above, a light modulation method that utilizes a phase transition phenomenon caused by a temperature change in a polymer liquid was proposed in an earlier application filed by the present inventors. There is.

One of the light modulation elements used in these prior inventions uses a polymer liquid as a heat-sensitive medium and uses a resistance heating element or radiation as a heating means.

The light modulation element according to the above-mentioned prior invention has various advantages such as its constituent materials are inexpensive, and since it utilizes resistance heating by electric current or heating by radiation as a heating means, the heating rate is high and control is easy. This is an excellent method.

(Problem to be Solved by the Invention) In the method of using a polymer liquid as a heat-sensitive medium as described above, in order to maximize its responsiveness, it is necessary to make the heat-sensitive medium respond even with a slight amount of heating. It is desirable to set the heat sensitive medium in advance to a temperature slightly lower than the critical temperature of the heat sensitive medium. However, although this allows the thermally sensitive medium to respond quickly to a small amount of heating, it slows down the natural cooling of the thermally sensitive medium when the signal input energy is interrupted, causing the thermally sensitive medium to return to its original state, i.e. below the critical temperature. The problem arises that it takes time for the temperature to cool down, and that it is not possible to respond sufficiently to rapid repetitive signal input.

Therefore, it is desirable to have an optical modulation method that can solve these problems and respond immediately to even a small amount of signal input energy, return to the original state immediately after the signal input is interrupted, and sufficiently respond to rapidly repeated signal inputs. .

The present inventor has arrived at the present invention as a result of intensive research in order to further solve the problems of the prior invention as described above and develop an excellent light modulation method.

(Disclosure of the Invention) That is, the present invention provides a light modulation method for modulating light by applying a thermal signal to a light modulation element made of a heat sensitive medium made of a polymeric substance and a liquid. This is a light modulation method characterized by cooling.

To explain the present invention in more detail, the light modulation element used in the present invention basically includes a substrate, a transparent protective plate having a certain distance from the substrate, and a transparent protective plate sandwiched between these substrates and the transparent protective plate. The present invention is characterized in that a polymer substance liquid that undergoes a phase transition due to temperature change is used as the heat-sensitive medium.

As the above-mentioned substrate and transparent protection plate, any conventionally known material can be used as long as it is inert to the solvent constituting the polymer substance liquid described below.For example, if the light modulation element is a light-transmitting type. In some cases, transparent plastic materials such as polyolefin, polyester, polyacrylic ester, polyurethane, polyamide, polycarbonate, etc., transparent inorganic materials such as glass, sapphire, etc. are used as both the substrate and the transparent protective plate; When the light modulation element is a light reflection type, the above-mentioned material is used as the transparent protection plate, and the substrate is a thin film of metal such as aluminum, a material that does not transmit light such as opaque plastic, or a metal coating. The above-mentioned plastic material on which is vapor-deposited can be optionally used. These substrates and transparent protection plates may be of any shape, whether translucent or reflective, and it is generally preferable to use a material with a thickness of about 0.01 to 0.411 mm. .

The first feature of the method of the present invention is that a polymeric material liquid consisting of a polymeric material and a liquid is used as the heat-sensitive medium of the light modulation element used in the method of the present invention. Such a polymeric substance liquid is configured such that by changing the combination of the polymeric substance and the liquid, the polymeric substance undergoes a phase transition in the liquid due to a temperature change. These phase transitions exhibit the following optical phenomena.

(1) Before heating, it is in a cloudy state with polymeric substances precipitated.
Although it has light scattering properties, when heated, the polymer material dissolves and becomes transparent, undergoing a phase transition to a state in which it does not substantially modulate incident light. It is then restored to its original state by cooling.

(2) Before heating, the polymer substance is in a dissolved state, and upon heating, it precipitates and becomes cloudy, causing a phase transition opposite to that in (1) above. It is then restored to its original state by cooling.

The polymeric substances used to prepare the polymeric substance liquid that undergoes the phase transition described above range from relatively low molecular weight polymeric substances conventionally called surfactants to higher molecular weight polymeric substances, and even higher molecular weight polymeric substances. , encompasses crosslinked polymeric materials that are not completely soluble in liquids but can form transparent gels.

Relatively low molecular weight polymer substances include polyoxyethylene carboxylic acid esters such as polyoxyethylene laurate, ethers of polyoxyethylene and phenols such as polyoxyethylene octylphenyl ether, and polyoxyethylene stearylamine. amines such as polyoxyethylene laurylamide, nonionic surfactants such as amides such as polyoxyethylene laurylamide, anionic surfactants such as sodium hexadecane sulfonate, sodium dodecylbenzenesulfonate, sodium dodecyl sulfate, hexadecyltrimethylammonium Examples include cationic surfactants such as iodite and hexadecylpyridinium iodide.

Examples of higher molecular weight polymers include polypropylene,
Polyalkenes such as polyisobutyne, polybutadiene,
Polydienes such as polyisoprene, polyvinyls such as polyvinyl acetate, poly(meth)acrylic acid ester, poly(meth)acrylamide, polystyrenes such as polystyrene, polyα-methylstyrene, or these and other polymeric substances copolymers consisting of monomers that form, polyethers such as polyethylene oxide and polypropylene oxide, polyimines such as polyethyleneimine, polyesters such as polyethylene succinate, polyethylene adipate, and polyoxyethylene adiboyl, polyglycine, and nylon. Polyamides such as 66,
Examples include silicone resins such as polydimethylsiloxane, polysaccharides such as cellulose acetate and aminopectin, other conventionally known polymeric substances, and mixtures thereof.

In addition, in the present invention, in addition to the polymeric substances that can form a solution as described above, there are also substances that are not completely soluble in the solvent.
It is also possible to use ultra-high molecular weight polymeric substances such as those mentioned above that absorb and incorporate solvents to form gels, and crosslinked polymeric substances obtained by crosslinking the above-mentioned polymeric substances. These crosslinked polymeric substances have the same effect as the above-mentioned polymeric substances, provided that the gel causes a reversible change in light transmittance←→light scattering property due to temperature change.

Such a crosslinked structure of a crosslinked polymer substance can be easily formed by a conventionally known method. For example, a method in which a polyfunctional monomer is partially used as a crosslinking agent during the production of the polymeric substance to form a crosslinked structure simultaneously with polymerization, a method in which a reactive monomer is used in combination to form a crosslinking point in the polymeric substance, A method of forming a crosslinked structure using this crosslinking point,
Any conventionally known method can be used, such as a method of crosslinking using radiation or the like.

The liquid used to form the polymeric material liquid from the polymeric material as described above may be any conventionally known organic solvent, water, or a mixture thereof.For example, water, methanol, ethanol, propatool, ethylene, etc. Alcohols such as glycol and glycerin, ketones such as acetone and methyl ethyl ketone, ethers such as dioxane, diglyme, and tet'-yhydrofuran, amides such as dimethylformamide and dimethylacetamide, and sulfur-containing solvents such as dimethyl sulfoxide; mixed solvents, and in these solvents, electrolytes such as acids, bases, and salts, and various solutes such as urea and glucose.

Examples include dissolved solutions.

The polymer substance liquid constituting the light modulation element used in the present invention is formed from the above-mentioned polymer substance and solvent.
A particularly important point is the combination of a polymeric substance and a solvent. It is necessary to create a combination that causes a phase transition phenomenon of precipitation→dissolution or dissolution→precipitation depending on the temperature change.

In forming a polymer substance liquid, the present inventor has determined that, by appropriately combining a polymer substance and a solvent, for example, as one standard, the critical dissolution temperature of a polymer substance in a solvent (when a single polymer substance is simply The temperature (corresponding to Flory's θ temperature shown in the solvent) is 5°C to 110°C, particularly preferably 20°C.
By combining a polymeric substance and a solvent so that the temperature falls within the range of ℃ to 75℃, the polymeric substance in the solvent can be changed from a precipitated state to a dissolved state or from a dissolved state to a precipitated state due to a temperature change, such as an increase in temperature. It was discovered that the material undergoes a phase transition and exhibits a change in translucency←→light scattering property. Such a polymer substance liquid is, for example, about 1 to 1,000 #Lm.
, preferably a thin layer of about 1 to 1100p, and by locally applying heat to this thin layer, a transparent part or a light-scattering part immediately appears in the heated part, and a transparent part immediately forms when the heat is removed. They also discovered that the light-scattering portion disappears, and found that their extremely excellent thermal responsiveness of dissolution (transparency) ← → precipitation (light-scattering) makes them useful as a heat-sensitive medium for light modulation elements. It is something.

A polymer substance liquid with such excellent thermal responsiveness can be easily formed by selecting a solvent suitable for the selected polymer substance and adjusting the solvent affinity of the polymer substance. Form an organic polymer substance solution or transparent polymer substance gel with a suitable solvent, and change the solvent affinity of the polymer substance while mixing a relatively poor solvent with it.
The thermal responsiveness of the polymer substance liquid formed can be adjusted to a preferable range by methods such as adjusting the thermal responsiveness, and even using methods such as using solvents with various mixing ratios or solvents with various concentrations of solutes added. You can also.

The heat-sensitive medium of the light modulation element used in the present invention, that is, the polymeric material liquid, forms a polymeric material liquid with a polymeric material temperature of about 0.2 to 25% by weight, and this is placed between the transparent protective plate and the substrate. It can be obtained by forming a thin layer having the thickness as described above. When the polymer substance concentration is below the above range, changes in optical properties due to temperature changes will be small;
If the concentration exceeds the above range, the response speed of the light modulation element will decrease, which is not preferable.

The above-mentioned light modulation device requires a means for applying heat to the polymer substance liquid layer according to the information signal, and it is preferable to incorporate such a heating means into the device in advance, but when using the device, It can also be installed. As a heating means,
Although any conventionally known means can be used, preferred examples include a resistance heating material that generates heat due to electrical resistance, and a material that generates heat by absorbing radiation such as infrared rays.

Such resistance heating layers are made of metals such as nichrome, alloys, transparent or opaque metal compounds such as hafnium boride, tantalum nitride, tin oxide, indium tin oxide, and conductive plastics such as carbon resin and metal glaze. can.

Further, the radiation absorbing layer can be formed from an inorganic or organic material that absorbs radiation at a target wavelength, and these materials include, for example, Si, Sio, 5i0
2, ZnS, As2 S3, AfL203, NaF,
Examples include Zn5e, Cd1ITb.Fe, carbon black, metal phthalocyanine, and various pigments.

The light modulation element used in the present invention is basically composed of the above-mentioned materials.

In addition, it is also effective to provide a protective layer on the surface of the heating means for the purpose of protecting the heating means from the polymer liquid.

These protective layers are made of polymeric materials such as methyl methacrylate, butyl acrylate, styrene-acrylonitrile copolymer, polyester, polyamide, etc., which are insoluble in the constituent solvent of the liquid layer, or silicon oxide,
Preferably, it is formed from an inorganic material such as titanium oxide. Further, the protective layer may be colored for the purpose of adjusting the contrast during operation of the light modulation element, or a colored layer may be provided separately from the protective layer for the same purpose.

When providing a protective layer or a colored layer, the distance from the resistance heating layer or infrared absorbing layer to the polymer material liquid layer should be 50 gm or less, preferably 1 gm, so as not to impede the rapid transfer of heat.
It is necessary to keep it below 0gm.

Note that the method of constructing the light modulation element, that is, the method of laminating the transparent protective plate, polymer material liquid layer, heat generating layer, protective layer, substrate, etc., may be a conventionally known method.

A second feature of the present invention is that when optical modulation is performed using the optical modulation element as described above, the heat applied to the heat-sensitive medium by signal input energy is immediately removed when the signal input is interrupted. Therefore, in order to quickly return the heat-sensitive medium to its original state, the device is provided with a cooling means for cooling.

Such cooling can be achieved using any conventionally known method, such as electronic cooling elements, heat sinks, cooling fans, refrigerant circulation,
Any method such as a heat pipe or a combination thereof can be used.

Note that since these cooling means are generally non-transparent, they should be provided on the side opposite to the incident surface of the element.

When optical modulation is performed using a light modulation element such as the one described above, for example, if the critical temperature of the heat-sensitive medium of the element is 50°C, the response to the input signal is somewhat slow at the beginning of the operation of the element, but recovery is quick. . As the operation continues, the temperature of the heat-sensitive medium gradually rises, and when it reaches close to the critical temperature of the heat-sensitive medium, the response becomes faster and recovery is delayed. Finally, when the temperature of the heat-sensitive medium reaches or exceeds a critical temperature, it loses its responsiveness.

Therefore, it is most preferable to carry out the cooling as described above so that the temperature of the heat-sensitive medium is several degrees Celsius lower than the critical temperature of the heat-sensitive medium.

The present invention will now be described in more detail with reference to the accompanying drawings, which schematically illustrate preferred embodiments of the light modulation method of the present invention.

FIG. 1 of the accompanying drawings schematically shows the method of the present invention using a light-reflecting light modulation element. In this example, a polymer substance liquid that is transparent and light-transmissive at low temperatures and precipitates and becomes light-scattering at high temperatures is used as the heat-sensitive medium.

The light modulation element 20 in FIG. 1 is composed of a transparent substrate 1 as described above, a polymer material liquid layer 2 as described above, and a protective plate 3 as described above. As a preferable means for applying heat to the layer 2, preferably light-transmitting resistance heating layers 4a, 4b... and a light-transmitting resistance heating layer for protecting these resistance heating layers from the solvent of the polymeric substance liquid layer are used. A protective layer 5 is provided. The resistance heating layer is connected to an external power source 7 for generating heat in the heating layer.
Elements 6a, 6 that operate as switches or similar
They are connected via b... Further, on the front surface of the protection plate 3 of the element 20, an electronic cooling element 8 and a heat sink 9 are provided as cooling means.

In the light modulation element of this example, when the switch is in the open state (6a), no power is supplied to the resistance heating layer 4a, and the polymer liquid layer 2 adjacent thereto is at a low temperature.
The layer 2 is in a transparent and uniform state in which the polymeric substance is compatible with the solvent. Therefore, the incident light 10a is reflected by the reflective protection plate 3 without being modulated and exits.

On the other hand, when the switch is closed (6b), the resistance heating layer 4
Power is supplied to b from an external power source 7, and at this time, the heat generated in the resistance heating layer 4b is transferred to the polymer material liquid layer 2 in the adjacent portion.
Raise the temperature. As a result, when the temperature of the liquid exceeds the critical temperature of the polymer material, the polymer material precipitates in the liquid medium, and the polymer material liquid layer 2 in that part becomes non-uniform, and the incident light
b is significantly light-scattering within the polymer substance liquid layer 2. In this way the purpose of light modulation is achieved.

In the above exemplary method, the cooling means 8.9 is linked with any means (not shown) for detecting the temperature of the polymeric substance liquid to control the temperature of the polymeric substance liquid to a temperature somewhat lower than its critical temperature. By doing so, a sharp repetitive response can be maintained for a long time.

In the example schematically shown in FIG. 2, an infrared absorbing layer 12 that absorbs infrared rays 11 and generates heat is used as a heating means to heat the substrate surface, instead of the resistance heating layers 4a, 4b, etc. in the example of FIG. This diagram schematically shows an example in which the cooling means 8 and 9 are provided on the back side of the substrate, and its operating principle is the same as the first one except that infrared rays are used instead of electric current as the heat source.
This is similar to the embodiment shown in the figure.

Furthermore, in place of the heating means shown in FIGS. 1 and 2, infrared absorbers, various pigments that generate heat by absorbing light of a specific wavelength, and ultraviolet absorbers that generate heat by absorbing ultraviolet rays may be used. It is also possible to add the light to the polymer liquid layer 2 in advance and use the light that is not absorbed by these light-absorbing exothermic agents at the same time. Although such an example is not shown, the light is It is obvious that modulation is possible.

In addition, in the above example, a material that precipitates upon heating and becomes light-scattering is used as the polymer substance liquid, but on the contrary,
Even in the case of using a polymer substance liquid that is dissolved and made transparent by heating, the other aspects are substantially the same as above, except that the transmission and scattering of light are reversed.

Next, the present invention will be explained in more detail with reference to preferred embodiments of the present invention.

Example! As shown in Figure 2, thickness 0.35a+m, size '40
On the front and surface of glass plate (substrate) 1 with +s shoes x 50 m.

A tantalum nitride film with a thickness of i and ooo angstroms was formed by sputtering, and then a photoresist was applied on this (7) M, and 20 mm/I was applied parallel to the short side of the glass plate.
After baking the stripe pattern 12, the excess tantalum nitride film was selectively removed by etching to obtain a resistive film 13 with a predetermined pattern. On top of that, the thickness is 2.0
00 angstrom indium-tin oxide (IT
o) Films were laminated by sputtering and patterned again by the same method to form conductive paths 14. I
Tantalum nitride film part without TO coating (size 40 pL)
'm×2.000gm) is used as the resistance heating layer 4. On top of this, ethyl methacrylate plasma treatment is performed,
1. A protective layer 5 was formed by forming a crosslinked polymer film of OBm.

On top of this, thickness 1100p, size 50+wmX30+
A Mylar film with a 40 mm x 10 m + W window in the center was glued using U+ so that the resistive heating layer that had been created was inserted into the window.

0.5 g of N-isopropylacrylamide and 3+ wg of ammonium persulfate were dissolved in cold water, 8 g of tetramethylethylenediamine was added, and the mixture was degassed under reduced pressure. The polymerization reaction was carried out by maintaining the temperature at 20°C for 30 minutes on a water bath. Drop this solution onto the window of the Mylar film prepared above,
A glass plate of size 50 x 30 cm and thickness of 0.35 m+m was placed over the film to prevent air bubbles from entering, and the peripheral portion of the film was sealed using an epoxy resin that cured at room temperature. Apply black acrylic paint to the top of the glass plate 3, air dry it, then apply silicone grease to it, and use this surface as the cooling surface side of an electronic cooling element (Peltier element) 8 with a size of 2.54 cm + w x 2.54 cm and a rating of 2V6A. pasted on. Silicone grease was also applied to the heat radiation surface side of the electronic cooling element, and a copper plate having a thickness of 1.6 mm and a size of 120 mm x 120 mm was crimped onto this as a heat radiator 9. A variable constant current power source with a rating of 5 A was connected to the electronic cooling element, and the light modulation element used in the present invention was obtained.

An external power source for heating the resistance heating layer 4 was composed of two function generators and a power amplifier. That is, the first function generator generates a relatively long period (2C) as − which determines the repetition period of element drive.
1,000m5) (1) Square wave (duty ratio 1/2
~1/100 ) and applied this square wave to the gate input of the second function generator. The second function generator was set to oscillate a sinusoidal alternating current at a specified frequency (20 Hz to 2 KHz) when a signal was applied to the gate input. This output was applied to the resistive heating element of the optical modulation element through a power amplifier. At this time, a plurality of arbitrary resistance heating elements in the element were connected in parallel. A 45 degree angle plate He −
N e laser beam (632.8m, 0.2mW
), and the light scattered by the heat-sensitive medium was observed using a photomultiplier from a direction perpendicular to the element surface, making it possible to evaluate the response to signal input. At an air temperature of 25°C, first, without supplying current to the electronic cooling element, a sine wave alternating current with a frequency of 800 Hz and an effective value of 22 V is applied to the resistive heating layer for 40 cycles at a time.
When +ss is added, the intensity of scattered light by the element starts to rise after a delay time of 5 minutes with respect to the power input, and the intensity increases by 20+m
The saturation level was reached at s. In addition, the scattering intensity started to decrease 80 s after the power supply to the resistance heating layer was cut off.
After 150m5, it returned to its original level.

Next, we conducted similar measurements while cooling the heat-sensitive medium by passing a current through the electronic cooling element.We found that as the amount of current for cooling was increased, the rise time of the scattered light intensity became longer.
It was observed that the fall time became shorter. It was also found that the increase in the rise time due to cooling can be suppressed by increasing the power supplied to the resistance heating layer.

Specifically, a current of 1.6 A is supplied to the thermoelectric cooling element, and a sine wave alternating current with a frequency of 800 Hz and an effective value of 42 ■ is applied to the resistance heating layer. When the light was supplied for 20 m5 at intervals of 7150 g and the light scattering was observed after reaching a thermal steady state, it was found that the city responded with a rising time of 5 Ils and a falling time of 6 ms.

By using the cooling element in this way, the optical response speed is improved.

Example 2 An infrared absorbing layer 12 was created by sputtering a Gd@Tb5Fe layer to a thickness of 1,500 angstroms on the surface of a glass plate 1 having a size of 50 mm x 50 m+* and a thickness of 0.35 layers. did.

Thickness 10gm, size 50sm x 40mm
Then I glued a Mylar film with a 40+m x 30mm window in the center.

0.5 g of isopropylacrylamide and 3 mg of ammonium persulfate were dissolved in cold water, tetramethylethylenediamine BJJ-1 was added, and the mixture was degassed under reduced pressure. The mixture was kept at 20°C for 30 minutes on a water bath to carry out a polymerization reaction. This solution was dropped onto the window of the film prepared above, and the size of the film was 50 m.
A glass plate 3 having a size of 40 mm x 0.35111 m and a thickness of 0.35111 m was covered to prevent air bubbles from entering, and the periphery was sealed with an epoxy resin that cured at room temperature. Apply black acrylic paint to the top of the glass plate, air dry it, then apply silicone grease, and then paint this surface with a size of 2, 54cm x 2, 54C.
11. It was attached to the cooling surface side of an electronic cooling element (Beltier element) with a rating of 2V6A. Apply silicone grease to the heat dissipation side of the electronic cooling element 8, and make it 1.6 mm thick and 12 mm in size.
A copper plate measuring 0 mm x 120 mm was press-bonded to this as a heat sink 9. A variable constant current power supply with a rating of 5A was connected to the electronic cooling element.

The apparatus for measuring the optical response speed had the same configuration as in Example 1, and an infrared removal filter was inserted on the input side of the photomultiplier.

When a pulsed semiconductor laser beam (wavelength: 833 nm, spot diameter: 50 gm) was applied to this device, the same results as in Example 1 were obtained.

That is, when cooling is not performed at room temperature of 25°C, the rise time is 60Ils when the semiconductor laser has a pulse output of 12mW, a period of Looms, and a duty ratio of 40%.
When a current of 1.2 A was supplied to the thermoelectric cooling element, the response was 9 mm at the rise and 9 Ils at the fall at a pulse output of 20 mW, a period of 501 S, and a duty ratio of 40%. An improvement was seen.

Example 3 4.8 g of N-isopropylacrylamide, 80 mg of N,N-methylenebisacrylamide, and 30 mg of ammonium persulfate were dissolved in 60 ml of cold water, and 150 pu of tetramethylethylenediamine was added and degassed under reduced pressure to obtain a seven-mer solution. .

This monomer solution was sealed between the same substrate and glass plate as in Example 1, and left at room temperature for 30 minutes to complete gelation of the seven-mer solution, and an electronic cooling element, a heat sink, etc. were attached. .

A driving test was performed on the light modulation element thus produced under the same conditions as in Example 1, and similar results were obtained.

Example 4 Polyoxyethylene urylamine (Etho+*e
-en C-15, manufactured by Kao Akzo) Ig, water 60m!
; Dissolved in L to obtain a surfactant solution. This surfactant solution was sealed between the same substrate and glass plate as in Example 1,
Further, an electronic cooling element, a heat sink, etc. were attached to fabricate a light modulation element. A driving test similar to that in Example 1 was conducted, and similar results were obtained.

Example 5 Methacrylamide 0.5g, ammonium persulfate 110
1 was dissolved in 30 ml of cold water, 30 ml of tetramethylethylenediamine was added, and the mixture was degassed using an aspirator.

After standing at room temperature for 30 minutes, 25 mJlj of methanol was added and heated to 60°C to obtain a polymer solution. Example 1
A similar substrate and a glass plate were heated in an oven to 60° C., during which time the above-mentioned polymer solution was sealed, and an electronic cooling element, a heat radiator, etc. were attached to prepare a light modulation element.

By cooling, the polymer solution inside the device became opaque.

Next, using the same test system as in Example 1, a driving test of this element was conducted. At an air temperature of 25°C, a frequency of 800H is applied to the resistance heating layer without supplying current to the electronic cooling element.
When 40 m5 of sine wave alternating current with an effective value of 28 V was applied at one time, the intensity of scattered light by the element began to fall after a delay time of 5 Ils with respect to the power input, and reached the saturation level at 65+++s.

Also, 95ffi after the power supply to the resistance heating layer was cut off.
The scattering intensity began to increase after 5 minutes, and returned to the initial level after 180 meters.

Next, a current of 1.4 A was supplied to the electronic cooling element, and a sine wave alternating current with a frequency of 800 Hz and an effective value of 42 V was supplied to the resistance heating layer for a period of 30 m5 at intervals of 60 m5 to reach a thermal steady state. After observing the backlight scattering, it was found that the response was 12 m5 in rise time and 1 oss in fall time.

(Effects) According to the present invention, the optical response speed of an optical modulation element using an 8-sensitive medium to an input signal is improved, and faster optical modulation becomes possible.

[Brief explanation of drawings]

1 and 2 schematically show a cross section of a light modulation element used in the present invention, and FIG. 3 schematically shows a substrate having a heating resistor layer used in an embodiment of the present invention. . l; Substrate 2; Polymer substance liquid layer 3; Protective plate 4; Heating resistance layer 5; Protective layer 6
; Switch -7; Power source 8.9; Cooling device 10; Incident light 11: Infrared rays 12; Infrared absorption layer 13; Resistive film 14; Conductive path A tongue; Light modulation element patent applicant
Motoyanon Co., Ltd. Agent Patent Attorney Yoshi 1) Katsuhiro'1. -11'I'
lFigure 3

Claims (1)

[Claims] (1) A light modulation method for modulating light by applying a thermal signal to a light modulation element made of a heat sensitive medium made of a polymeric substance and a liquid, characterized in that the heat sensitive medium is cooled during operation of the element. Light modulation method.