Digital electronics meets its match (acoustooptic devices)

The promise shown by acoustooptic (AO) spectrum analyzers and correlators in field-test prototypes for radar, communications and electronic-warfare surveillance is discussed. The principle of operation of AO devices is explained, and its use for correlation and convolution is examined. Two types of Bragg cell (the basic AO component) are described: surface-acoustic-wave (SAW) and bulk cells. The use of a 2-D AO correlator (i.e. one that moves its output beam over an array of photodetectors rather than a single line) in a spread-spectrum receiver is presented to exemplify the use of AO devices.>