A detailed analytical study of optical scattering from a parallel ultrasonic setup is presented in which an optical beam is scattered by a surface acoustic wave that acts as a Raman-Nath-type dynamic grating and the scattering is controlled and monitored by a bulk (Bragg) acousto-optic grating placed adjacent to the surface wave. To generalize this mixed configuration, we assume the two ultrasonic cells to have a frequency ratio p:q. The intensities of the final scattered orders of light are analyzed by a multiple plane-wave scattering formalism and plotted for varying frequency ratios, Q’s, and peak phase delays ( ��̂). Finally, a dynamic detection method is proposed for identifying the characteristics of a surface acoustic wave with the parallel ultrasonic technique.