JPS60242431A - Optical deflector - Google Patents

Abstract

PURPOSE:To speed up the response of the deflection of a light beam and obtain a relatively large angle of deflection by coupling one heat absorbing surface of each Peltier element, provided on the top and reverse surface of an optical material which varies in refractive index with temperature, through a heat conductive member. CONSTITUTION:Heat absorbing surfaces of Peltier elements 2 and 3 at the opposite sides of lithium niobate crystal 1 are fixed to the U-shaped heat conductive member 11 is contact. Power sources 7 and 8 flow a current to the elements 2 and 3 to heat the top surface of the crystal 1 by, for example, the element 2 and cool the reverse surface of the crystal 1 by the element 3. Heat is well concucted from the heating side to the cooling side through the conductive member 11, so the time in which a stationary temperature gradient is obtained in the crystal 1 is shortened and the temperature gradient is relatively large. Consequently, a relatively large refractive index gradient is obtained in the crystal 1 and a light beam made incident on an end surface of the crystal 1 is deflected at a relatively large angle of deflection.

Description

DETAILED DESCRIPTION OF THE INVENTION BACKGROUND OF THE INVENTION This invention relates to an optical deflector using an optical material whose refractive index changes depending on temperature.

It is known that the refractive index of glass, dielectric materials, etc. changes depending on temperature. It is conceivable to deflect light using an optical material that produces such a thermo-optical effect. In order to change the temperature of an optical material, it is conceivable to provide a Vertier element on its surface.

FIG. 5 shows an example of an optical deflector in which Vertier elements are provided on the upper and lower surfaces of an optical material. Dielectric crystals with thermo-optical effects, such as lithium niobate (LiNb)
Vertier elements (2>(3
) are provided for each. Beltier element (2>(3
), as is well known, at least one set of semiconductors (5) of different conduction types is provided between a pair of heat exchanger plates (4),
These semiconductors (5) are connected in series so that the P-type and N-type are alternated by connecting conductors (paths shown) fixed to the heat exchanger plate (4). Semiconductor (5)
When a direct current is passed through, one of the pair of heat exchanger plates (4) generates heat, and the other heat exchanger plate (4) absorbs heat. When the direction of the current is reversed, the heat exchanger plate (4) where heat is generated and the heat exchanger plate (4) where heat is absorbed are reversed. The outer surface of the heat exchanger plate (4) is a heat generating and endothermic surface. Each of the Vertier elements (2) and (3) is fixed to the crystal (1) with the heat-generating and endothermic surface of one heat exchanger plate (4) in close contact with the top or bottom surface of the crystal (1). Each Vertier element (2) (
A heat-radiating and heat-absorbing fin (6) is fixed to the heat-generating and heat-absorbing surface of the other heat exchanger plate (4) in 3).

Heat transfer plate (4) on the crystal (1) side of the upper Vertier element (2)
), a current is passed from the power source 7) to this Beltier element (2) so as to generate heat, and the lower Beltier element (3)
When a current is passed from the power source (8) to this Vertier element (3) so as to cause the heat transfer plate (4) on the crystal (1) side to absorb heat, the upper surface of the crystal (1) is heated and the lower surface is cooled. be done.

As a result, a temperature gradient is generated inside the crystal (1) in the vertical direction, and this temperature gradient causes a refractive index gradient inside the crystal. In this case, a refractive index gradient occurs in which the refractive index in the upper part of the crystal (1) becomes higher and the refractive index in the lower part becomes lower.

When a light beam A is made incident from the end face of the crystal (1) parallel to the upper and lower surfaces of the crystal (1), the light beam is deflected in the vertical direction due to the gradient of the refractive index. The deflected output beam is
and the undeflected output beams are indicated at 81, respectively. To deflect the light beam downward, a Bertier element (2
) (3) by reversing the direction of the current flowing.

FIG. 6 shows the state of heat conduction in such an optical deflector. Heat is absorbed from the air through the fins (6) provided on one Vertier element (2), passes through this Vertier element (2), the crystal (1) and the other Vertier element (3), It is released into the air via the fins (6) provided on the Vertier element (3). Since heat is absorbed from the air, which has a low thermal conductivity, and released into the air, heat conduction within the crystal (1) is insufficient. For this reason, there are problems in that it takes time to obtain a steady temperature gradient, the deflection response is relatively slow, and since a relatively large temperature gradient cannot be obtained, a very large deflection angle cannot be obtained.

SUMMARY OF THE INVENTION An object of the present invention is to provide an optical deflector that has a relatively fast response in deflecting a light beam and can obtain a relatively large deflection angle.

In the optical deflector according to the present invention, Beltier elements are provided on the upper and lower surfaces of an optical material whose refractive index changes depending on temperature, and one heat-generating and endothermic surface of each Beltier element is fixed in close contact with the upper and lower surfaces of the optical material. The optical deflector is characterized in that the other heat generating and heat absorbing surfaces of each Vertier element are coupled to each other via a heat transfer member.

Typical optical materials with thermo-optical effects include:
Glass, T! 02, L! Examples include Nb0a and PLZT. As the heat transfer member, a material having good heat conductivity such as copper or silver is used.

By passing current through the Vertier elements provided on the upper and lower surfaces of the optical material, one of the upper and lower surfaces of the optical material is heated and the other surface is cooled. At this time, since heat is well conducted through the heat transfer member between the heating side and the endothermic side, the deflection response becomes faster and a relatively large temperature gradient can be generated within the optical material.

As a result, a relatively large refractive index gradient within the optical material can be obtained, and a relatively large optical deflection angle can be obtained.

DESCRIPTION OF THE EMBODIMENTS In FIGS. 1 to 4, the same parts as in FIG. 5 are denoted by the same reference numerals, and the explanation thereof will be omitted.

FIG. 1 shows a first embodiment of the invention.

One of the heat-generating and endothermic surfaces of the upper and lower pair of Vertier elements (2) and (3) is coated with silicone grease on the upper and lower surfaces of the crystal (1), respectively, in order to improve heat conduction with the lithium niobate crystal (1). It is tightly fixed. Each Vertier element (
2> Heat exchanger plate (4) on the opposite side to the crystal (1) side in (3)
) is a U-shaped heat transfer member (
11) is closely fixed to the lower surface of the upper horizontal part (11a) and the front of the lower horizontal part (Ilb).

For example, copper is used as the heat transfer member (11).

Bertier elements (2) (3) from electric m(7> and (8))
For example, the upper Bertier element (
When the front side of the crystal (1) is heated by 2) and the lower side of the crystal (1) is cooled by the lower Vertier element (3),
A temperature gradient occurs in the vertical direction within the crystal (1), and this temperature gradient provides a refractive index gradient. At this time, since heat is well conducted between the heating side and the cooling side through the heat transfer member (11), the time required to obtain a steady temperature gradient is relatively short, and the inside of the crystal (1) A relatively large temperature gradient is obtained. Therefore, a relatively large refractive index gradient is obtained inside the crystal (1), and the light beam A that is incident parallel to the upper and lower surfaces of the crystal (1) from the end face of the crystal (1) is deflected at a relatively large deflection angle. It has the advantage of being possible.

2, 3, and 4 show the second and third embodiments of this invention.
and a fourth embodiment, in which the shape or structure of the heat transfer member is different from that of the first embodiment. In the optical deflector shown in Fig. 2, a rectangular frame-shaped heat transfer member (12) is used, and a heat transfer plate ( 4), the heat-generating and endothermic surface of the heat-transfer member (12)
2b) respectively fixed on the upper surface. This optical deflector has the advantage of being more rigid in structure than that of the first embodiment. In the optical deflector shown in FIG. 3, an elliptical annular heat transfer member (13) is used. In the optical deflector shown in FIG. 4, a heat transfer member (14) is used which has a rectangular frame shape and is divided into an upper part (14'a) and a lower part (14b). The upper part (14a) and the lower part (14b) are connected and fixed by screws (15). This optical deflector has the advantage that it is easy to assemble, and the heat transfer member (14) and Peltier elements (2) and (3) can be connected by firmly screwing the screw (15).
And since the Vertier elements (2) and (3) and the crystal (1) can be brought into close contact with each other at their joints,
This has the advantage of improving heat conduction at these joints.

[Brief explanation of drawings]

FIG. 1 is a front view showing a first embodiment of the invention, FIG. 2 is a front view showing a second embodiment of the invention, FIG. 3 is a front view showing a third embodiment of the invention, and FIG. The figure is a front view showing a fourth embodiment of the present invention, FIG. 5 is a side view showing an optical deflector in which Peltier elements are provided on the upper and lower surfaces of an optical material, and FIG. 6 is an optical deflector shown in FIG. 5. It is a figure showing the state of heat conduction of a container. (1)...Thermo-optical dielectric crystal, (2)(3)...
Peltier element, (11) to (14)...heat transfer member. Figure 1 above

Claims (1)

[Claims] In an optical deflector, Bertier elements are provided on the upper and lower surfaces of an optical material whose refractive index changes depending on temperature, and one heat-generating and endothermic surface of each Bertier element is fixed in close contact with the upper and lower surfaces of the optical material. An optical deflector characterized in that the other heat generating and heat absorbing surfaces of the Vertier elements are coupled to each other via a heat transfer member.