SU1406554A1 - Colinear acoustic-optical filter - Google Patents

Abstract

The invention relates to the field of acoustooptics, more specifically to devices for spectral analysis using anisotropic interaction of acoustic and optical waves. The purpose of the invention is to improve the filter performance. The goal is achieved by the reflection of the sound beam from the input face of the filter at an angle about arctg (Pj5 / P j), where P and are the photoelastic constants of the crystal. In this case, the light propagating along axis 100 does not interact with the reflected sound beam. The absorption of the reflected sound is carried out in the absorber deposited on the side face of the filter, and the re-reflected sound beam is absorbed and scattered in a circular aperture in the sound. 1 il. (L

Description

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The invention relates to acousto-optics, namely to spectral analysis devices using anisotropic interaction of acoustic and optical waves.

The aim of the invention is to improve the shape of the hardware function (by eliminating parasitic transmission windows) of an acousto-optic collinear filter.

The drawing shows the filter design.

The device contains two polarizing prisms 1, two compensating prisms 2, a duct 3 with a piezo transducer 4 attached to it and a sound absorber 5. In the sound conductor perpendicular to the facet (010) a through hole 6 is made

The filter works as follows.

The light passed through the input polarization prism 1 and the compensating prism 2 propagates a collinearly sonic wave in the direction C100 of the crystalline acoustic duct. A longitudinal wave, excited by a piezoelectric transducer 4, propagates in. the direction C001 is converted on the output face into a shear with an offset to 001 extending in the direction of the LME. Due to the photoelastic effect, a collinear acousto-optical interaction of the light and shear acoustic waves occurs. The effective photoelastic constant is

The shear acoustic wave, reflected from the input face, propagates in the direction where the effective photoelastic constant t is zero, and hits the absorber. That part of the SOUND BELT wave, which due to: the difference in acoustic impedances reflected from the crystal / absorber interface, is reflected from the generatrix of the hole surface and again hits the absorber. Thus, the absence of interaction areas with spurious acoustic patches is achieved, and the hardware function does not have spurious transmittance windows.

The filter consists of 2 calcite polarization prisms, 2 compensating prisms from CaMo04, a sound line from CaMo04, belonging to the scheelite group. A piezoelectric transducer from LiNbO Y + 136 ° cut, 3x3 mm aperture is attached to the sound conductor with dimensions 70x. X10x14 by diffusion welding. The absorber is made of epoxy resin with a filler of fine Cu.

The entrance face of the sound duct is oriented so that the normal to it forms an angle of 2230, perpendicular to the facet (010) of the sound duct, a hole of 0 3.5 mm is made, the hole is located at the place of arrival of the sound beam reflected from the absorber.

Claims (1)

Invention Formula Collinear acousto-optic filter. consisting of a first polarization prism successively located on the same optical axis, a first compensating prism, a sound guide from a single crystal of the scheelite group, oriented along direction 100, the normal input and output faces of which lie in mutually orthogonal planes with a piezoelectric transducer attached to the light guide. a sound absorber, a second compensating and a polarization prism, characterized in that, in order to improve the filter transmission characteristic, the input edge of and it is oriented so that the normal thereto makes an angle with the direction oi equal to 100  - {- arctg (P, y / P45), where and Pjt are the photoelastic crystal constants, and a perpendicular to the granular m 001 of the light emitter in the direction of propagation of the sound wave close to the absorber, a through hole 1.1 1.1.2 in diameter with the aperture of the piezoelectric transducer is made. 010 OOi t5 / 100