Diffraction of light in intermediate regime of acoustooptical interaction at oblique incidence

The diffraction of light by ultrasound in an isotropic medium at arbitrarily small angles of incidence onto the acoustic layer is calculated. The intermediate regime of diffraction is considered, for which the conditions of observation of the Raman-Nath and Bragg diffraction are not satisfied in terms of the wave parameter. The effect of the acoustooptical interaction length and angle between the incident light beam and the acoustic wave on the light intensity distribution over the diffraction peaks is studied as a function of the acoustic power. Specific features of the transition from the Raman-Nath to the Bragg diffraction regime through the intermediate regime of diffraction are analyzed.