A function approximating the response of an acousto-optic delay line to a rectangular input action was determined in view of the structural, electrical, and physical parameters of an acousto-optic modulator, laser, and photoelastic medium. The duration of the input pulse and the cross-sectional diameter of the laser beam are the decisive factors in the formation of the output response. The diffraction efficiency was calculated. The results were experimentally verified for the case of the application of a rectangular pulse to the delay-line input. The waveforms of the input and output pulses are presented.