JPS58147716A - Light deflecting element - Google Patents

Abstract

PURPOSE:To attain high light deflecting efficiency by heating one surface of an alkali halide crystal element and by projecting laser light on the element parallel to the heated surface. CONSTITUTION:One surface of a crystal element 10 at the side of comb-shaped electrodes 21, 22 is heated by generating heat from the electrodes 21, 22, and the other surface 23 opposite to the electrodes 21, 22 kept at a constant temp. When the element 10 is in the heated state, the interplanar spacing of parts of the element 10 close to the electrodes 21, 22 is wider, and the interplanar spacing of a part far from the electrodes 21, 22 is narrower. Accordingly, the parts close to the electrodes 21, 22 have a lower intermolecular density, and the surface 23 opposite to the electrodes 21, 22 has a higher intermolecular density. Since the refractive index of light passing through a transparent crysta body is higher at a part having a higher density, projected laser light is deflected toward the surface 23 opposite to the electrodes 21, 22 as shown by the solid line, and it emerges from the element 10.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an optical deflection element that deflects light by thermally changing the refractive index inside a crystal.

The optical deflection element of the present invention was developed by focusing on the fact that the shorter the interlattice spacing of the crystal lattice constituting the transparent crystal body, that is, the higher the density, the higher the refractive index of light passing through the crystal body. To provide a deflection element that is easily available, inexpensive, and has high deflection efficiency. FIG. 1 is a perspective view of an embodiment of the present invention. In the figure, 10 is a transparent crystal element, and 21 and 22 are a pair of intersecting comb tooth electrodes. This pair of comb tooth electrodes are Cr −
It is made of Au and is formed on one surface of the crystal element 10 by sputtering.

The crystal element 10 and the comb tooth electrodes 21 and 22 form the optical deflection element 1.
00 is formed. Reference numeral 30 denotes a power source connected between the comb tooth electrodes 21 and 22, and although a high frequency power source is used in the embodiment, a DC power source may also be used. 40 is a comb tooth electrode 21
．． 22 and is a laser light source arranged so that it is projected onto the crystal element 10. As the crystal element 10, a LiF crystal element is used in the embodiment.

The laser light source 40 emits light onto the crystal element 10. On the other hand, the power source 30 applies a high frequency voltage to the comb tooth electrode 21.
．． 22. A capacitance C exists between the electrodes 21 and 22. Therefore, when a high frequency electric field is applied between the electrodes 21 and 22, the comb tooth electrode generates heat due to the loss tanffK of the capacitance C. This heat is transferred into the crystal element 10. LIF is used for the crystal element 10. LiF
is one of the alkali halide crystals, and its coefficient of thermal expansion (
electrostriction constant) is large.

An explanatory diagram of the operation of the optical deflection element 100.0 is shown in FIG.

crystal! On the comb tooth electrode 21.22 side of the child 10, the electrode 21.
It is heated by the heat generated by 22. A surface 23 of the crystal element 10 opposite to the electrodes 21 and 22 is maintained at a constant temperature. After the crystal element 10 is in the above thermal state, the crystal element 1
In the interior of 0, the inter-lattice spacing is wide in the portion near the electrodes 21 and 22K, and the lattice spacing is narrow in the portion far from the electrodes 21 and 22. That is, the intermolecular density is low in the portions close to the electrodes 21 and 22, and the density is high on the opposite side 23. As mentioned above,
The refractive index of light passing through a transparent crystal is greater when the density is greater. Therefore, the projected laser beam has a large refractive index, that is, it is polarized in the direction opposite to the comb tooth electrodes 21 and 22 and is emitted as shown by the solid line.

Here, in the embodiment, a LiF crystal element is used as the crystal element 10, but as described above, this LiF crystal element has a large coefficient of thermal expansion. A large thermal expansion coefficient of 0 indicates a density difference within the crystal element 10.

That is, the density of the part near the electrodes 21 and 22 is opposite to -23
This means that there is a large difference between the density of A large density difference means a large refractive index difference, that is, a large deflection angle, or in other words, a high conversion efficiency. L from conventionally known optical deflection elements such as PLZT or LiNbO3
iF has a larger coefficient of thermal expansion.

Therefore, the deflection efficiency of the optical deflection element according to the present invention using a LiF crystal element is higher than that of conventionally known elements. Furthermore, since the LiF crystal element is a unidirectional crystal, it is easily available and inexpensive.

In addition, in the example, Li was used as a crystal with a large coefficient of thermal expansion.
Although the case using F crystal was illustrated, other examples such as KNaCJ,
Since the crystal of NaF, KCg, MgO, IGr$ 7 #kalihalide has the same coefficient of thermal expansion as the LiF crystal of the example, it can be used as a highly efficient optical deflection element like the optical deflection element composed of the LiF crystal element. be able to.

However, these crystals need to be coated with a water-resistant coating.

As explained above, since the crystal element is constructed using an alkali halide crystal having a large coefficient of thermal expansion, according to the present invention, an optical deflection element with high deflection efficiency can be obtained.

[Brief explanation of the drawing]

FIG. 1 is an oblique view of the optical deflection element according to the present invention, and FIG. 2 is a dog-eared diagram explaining the operation of the optical deflection element of FIG. 1. ◎ 10...Crystal element, 21. ．． 22... Electrode, 3o.
...Power supply, 4o...Laser light source. M1 figure n Ryo2 figure 0

Claims (1)

[Claims] A 6-light polarizing element in which one surface of an alkali halide crystal element is heated and a laser beam is projected onto the crystal element parallel to the heated surface.