Analysis of quality of images obtained by acousto-optic filtering

Abstract

The paper is devoted to the theoretical and experimental investigation of spatial resolution of images obtained during acousto-optic spectral filtration. The consideration was carried out for a wide angle acousto-optic filter designed on the base of paratellurite single crystal. The crystal was cut in the (1 1 0) plane with the direction of acoustic wave propagation at the angle 10 ° relative to the axis [110]. It was found that optical quality of a filtered image is influenced by a spectral bandwidth of a filter. The spectral bandwidth is determined by a length of piezoelectric transducer that generates ultrasonic waves in an acousto-optic cell. The dependence of a number of resolvable spots on the piezotransducer length was examined theoretically. It was shown that a wavelength of the filtered radiation influences the quality of the processed image. Precise and approximate equations have been derived to determine the spectral passband of the acousto-optic filer, the angular field of view of a single pixel, the angular aperture of the device and the number of resolvable spots in a line. Resolution of the images obtained during the acousto-optic filtration was also measured in the experiment.