Acouso-optic processing of images in ultraviolet, visible and infrared regions of spectrum

摘要

The paper is devoted to analysis of regular trends and peculiarities of optical image processing by means of tunable acousto-optic filters. One of the goals of the investigation was to determine basic reasons limiting spatial resolution in acousto-optically processed images. As found, the limitations originate from laws of Bragg acousto-optic interactions in birefringent crystals. A case of the wide angle geometry of light diffraction was examined for the single crystal of paratellurite. It is shown that optical quality of the processed images depend on such interaction characteristics as mutual directions of propagation of optic and acoustic waves in the crystal, on dimensions of piezoelectric transducers launching acoustic waves in TeO_2, on optical wavelength and also on linear and angle apertures of optical beams. It is proved in the paper that the spatial resolution during the acousto-optic imaging depends on all these factors in a very complicated manner so that selection of an optimal cut of the birefringent crystal occurs not simple and evident. A trade-off between the spatial resolution and the optical throughput of the imaging device at various optical wavelengths is required. A detailed consideration of the problem becomes necessary depending on a particular problem to be solved by the acousto-optic filter. General methods to design the acousto-optic imaging devices operating in the ultraviolet, visible and infrared regions of spectrum are also discussed in the presentation.