The features of the nonreciprocal effect observed during collinear acoustooptic interaction in a lithium niobate crystal are investigated theoretically and experimentally. It is shown that one of the main reasons that restrict the possibility of observation of the nonreciprocal effect in the crystal is damping of an acoustic wave. It is proved that, when an acoustooptic cell is illuminated with monochromatic light, the ultrasound damping increases the frequency band of the collinear acoustooptic interaction, a circumstance that affects the possibility of observation of the nonreciprocal effect in an acoustooptic experiment. The conclusion that the creation of acoustooptic filters having a high spectral resolution and operating at acoustic microwaves necessitates taking into account the nonreciprocal effect is drawn.
