Hans Eschler

Performance limits of acoustooptic light deflectors due to thermal effects

Transducer conversion losses as well as acoustic and optic attenuation in solidstate acoustooptic light deflectors are responsible for temperature and stress fields which lead to deformation, index fields and changes in acoustic wavelength. For users, these effects result in beam deflection, lensing, aberration and a deterioration in efficiency. The known Maréchal criterion and a new criterion noted by the author set a limit of about one quarter wavelength to optic and acoustic wave aberrations. Maximum deflection efficiencies and light powers are determined as functions of the geometry, thermal boundary conditions, material constants and operating modes. A new thermal figure of meritMth 1 equalizes the differences of the acoustooptic figures of meritM2. To corroborate the theoretical results, performance limits for typical operating modes have been measured. Some new deflector designs are proposed and experimentally verified on the basis of the theoretical results.