JPS59164530A - Optical modulating element - Google Patents

Abstract

PURPOSE:To hold the inside of a resistor at a nonuniform temperature to increase the variable amount by providing the transparent resistor, electrodes formed opposite to the surface of the resistor, and a power source which impresses a voltage to said electrode to vary the voltage to be impressed. CONSTITUTION:An optical modulating element 1 consists of the transparent cubic resistor 10, transparent electrodes 21 and 22 provided on the incidence side and projection side of the resistor 10 as to light A, and radiators 31 and 32 provided on the top and reverse surfaces of the resistor 10, and the electric power E which controls the voltage to be impressed is connected to the electrodes 21 and 22. Consequently, the voltage impressed between the electrodes 21 and 22 is varied to make the refractive index in this resistor nonuniform, increasing the variable amount of resistance.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a light modulation element, and particularly to a light modulation element that can electrically modulate light.

Conventional light modulation elements that use liquid crystals and electro-optic crystals are known, but these all have small changes in refractive index, so the amount of modulation is small, and generally the polarization of incident light is small. Since it modulates depending on the state, it has the disadvantage that its applications are limited.

Recently, it has been discovered that when heat is applied to a substance, the refractive index changes, and when light is incident on this heated substance, the emitted light is deflected.For example, Nikkei Electronics August 16, 1982
185-193, it is reported that a He-Ne laser is irradiated onto a rutile (TiO2) crystal to which a DC voltage is applied, and that the deflection angle of the emitted light changes when the applied voltage is changed. ing. The present inventor focused on the phenomenon of light deflection caused by heat, utilized the temperature dependence of the refractive index of a substance, discovered non-uniform changes in the refractive index due to thermal changes, and based on this knowledge, invented the present invention. I came to do this.

In view of the above points, an object of the present invention is to form opposing electrodes on the surface of a transparent resistor as a medium, and change the amount of heat generated by the resistor by changing the voltage applied between the electrodes. The object of the present invention is to provide a novel light modulation element that modulates light by making the refractive index within the resistor nonuniform.

An embodiment of the present invention will be described below with reference to the drawings. 1st
The figure shows a light modulation element 1 which is an embodiment of the present invention. The light modulation element 1 is a transparent rectangular parallelepiped resistor lO
The resistor 100 is made up of transparent electrodes 21 and 22 provided on the incident and exit sides of the light A, respectively, and radiators 31 and 32 provided on the upper and lower surfaces of the resistor 10, respectively.
A power source E that can control the applied voltage is connected to the electrodes 21 and 22.

Next, the operation of the above embodiment will be explained. Stained pole 2 by power supply E
When a voltage is applied between 1.22 and 1.22, heat is generated due to the current flowing inside the resistor 10. The center of the resistor 10 in the direction of light A is the y-axis, the surface where the resistor 10 and the electrode 21 are in contact is the y-axis, the thickness of the resistor 10 in the X direction is 2a, and the length in the X direction is b. .

Assuming that the current density and electrical conductivity of the resistor 10 are uniform, the amount of heat generated at the point (X, y) of the resistor 10 is constant regardless of x + Y. Further, assuming that b is sufficiently thicker than 2a, the temperature inside the resistor is considered to be a function only of y. Therefore, from the heat conduction equation. Here T(x, y) is the temperature at point (X, y). According to the equation (1), L T (x, y') is a quadratic function of y, but the interface between the resistor 10 and the heatsink 31 (y=a) and the interface between the resistor 10 and the heatsink 32 Assuming that the temperature at the interface (y=-a) with T(X
, y), the first-order term of y disappears. That is, T(x, y)=Cyy2+To ·---(2) is obtained. Here, To is the temperature on the X axis, and C1 is a constant. Usually, the refractive index changes in proportion to temperature change, so the refractive index n (X
+ V) is n (x, y) = C2y”
−(3). Here, no is the y-axis refractive index of the resistor 10, and C2 is a constant. Therefore, according to equation (3),
The refractive index n(x, y) of the resistor 10 is an even function of y,
At least approximately, it has a cylindrical lens effect. That is, the temperature coefficient an/dT of the refractive index of the resistor 10
is positive, the resistor 10 has a convex lens effect, and dn
When /dT is negative, it has a concave lens effect.

In the above example, the heat radiation conditions of the heat sinks 31 and 32 are kept constant, but if these conditions are changed, the temperature in the X direction and the temperature in the -X direction will be different, so the emitted light will be
It is possible to deflect according to the non-uniformity of the resistor 10.

In the above-mentioned embodiment, a rectangular parallelepiped transparent resistor is used, so this resistor has a cylindrical lens effect, but as shown in FIG. That is, if transparent electrodes 21 and 22 are provided on the light incident side and the light output side, this light modulation element 32
It has a spherical lens effect.

FIG. 3 is a perspective view of the light modulation element 3 which is a modification of the embodiment shown in FIG. Electrodes 21 and 22 are provided on opposite sides of the transparent rectangular parallelepiped resistor 10, and a heat sink 3 is provided on the other opposite side.
1.32. In this light modulation element 3, since the light A is made incident as shown by the arrow in the figure, the electrodes 21 and 22 are
Although it does not need to be transparent, it is clear that it has a cylindrical lens effect like the light modulation element 1 in FIG.

If the incident surface of the light A of the light modulation element 1°2.3 in FIGS. 1, 2, and 3 is provided with a curvature in advance, or a member having nonuniform refractive index is provided, the voltage It is possible to produce an imaging effect even in a state where no energy is applied, and the heat sinks 31 and 32 can be made of Vertier elements, but may be naturally air-cooled depending on the purpose of the element. In short, it is important to create non-uniformity in the refractive index inside the resistor 10. In the present invention, since heat is generated within the medium itself through which the light passes, an effective first use of heat is possible. No prismatic action occurs,
Can be used as a variable focus lens. Moreover, the essence of the present invention is to cause a transformation of the wavefront of the incident light, which indicates that the intensity of the light can also be modulated by the well-known Schlieren optical system.

As explained above, by forming opposing electrodes on the surface of a transparent resistor and changing the voltage applied between these electrodes, the refractive index inside this resistor was made non-uniform. It is possible to provide a large light modulation element and its applications are unique.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of one embodiment of the invention, FIG. 2 is a perspective view of another embodiment of the invention, and FIG. 3 is a perspective view of another embodiment of the invention. 1.2.3・Light modulation element 10...Transparent resistor 21.22・Electrode 111r! lJ Figure 2! 3rl! :I

Claims (1)

[Scope of Claims] A transparent resistor, electrodes formed opposite to each other on the surface of the resistor, and a power source for applying a voltage to the electrode, and by changing the applied voltage, A light modulation element characterized in that the temperature inside the resistor is made non-uniform and the refractive index is made non-uniform.