Acousto-optic filters on potassium dihydrogen phosphate with optimal angle aperture and maximum beam deflection

Abstract

Results of a theoretical analysis on tunable acousto-optic imaging filters using potassium dihydrogen phosphate crystals are presented. It is found that the maximum angular aperture of an imaging filter at the optical wavelength 0.3 µm is equal to 3 deg. The diffraction efficiency in the examined instrument reaches 30% at moderate levels (2 W) of electric driving power. This performance may be obtained in a cell based on the (010) plane of acousto-optic interaction with the cut angle (18.8 deg) evaluated relative to the [100] axis. The device uses a piezoelectric transducer with dimensions 2.7×1.1 cm2 generating a slow shear elastic wave in the crystal. The spectral resolution of the filter is equal to 12 cm−1; the spatial resolution is characterized by 550×800 resolvable pixels in an image processed by means of the filter with linear aperture 0.8×1.1 cm2.