Аннотация:The work is devoted to detailed analysis of acousto-optic effect in biaxial crystals by an example of alpha-iodic acid crystal which belongs to the 222 symmetry class. The emphasis is on the Bragg angle frequency dependencies for different acousto-optic interaction planes, as well as on calculations of the acousto-optic figure of merit for isotropic and anisotropic diffraction and for different propagation directions of interacting optical and acoustic waves. The transfer functions of acousto-optic interaction are obtained and analyzed which describe the influence of an acousto-optic cell on optical images. It is found in particular that an alpha-iodic acid based collinear filter can exceed well-known calcium molybdate filters by 2 times in resolution and by 3.5 times in power consumption.