In some applications, the performance of multichannel Bragg cells is compromised by the spreading of the acoustic waves as they propagate; the spreading causes the signals in the channels to overlap. The overlapping can be significantly reduced by a spatial filter in a Fourier-image plane. The spatial filter is shown to be a cylindrical lens whose power is a function of the distance from the transducer. The effects of changes in the drive frequency as well as those of displacements of the filter are calculated. The reduction in the modulation transfer function as a function of propagation distance is calculated, and some bounds on the time-bandwidth product and the number of channels are dserived. In general, the overall performance can be improved by increasing the center frequency of the Bragg cell while keeping the bandwidth fixed.
© 1983 Optical Society of America
A. VanderLugt, G. S. Moore, and S. S. Mathe, "Multichannel Bragg cells: compensation for acoustic spreading," Appl. Opt. 22, 3906-3912 (1983)