1 August 1979 Acousto-Optic Implementation Of Real- And Near-Real-Time Signal Processing
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Acousto-optic devices have been developed for implementing advanced signal processing functions required for real-time and near-real-time analysis of both high-frequency radar signals and low-frequency sonar signals. These devices use the Bragg interaction between laser beams and surface acoustic waves (SAWs) to perform waveform convolution and correlation, achieving time-bandwidth products of 3000 to 10,000 with dynamic bandwidths of several hundred megahertz. Using these devices, wideband (about 100 MHz) signals have been extracted from extremely noisy environments (-30 dB signal-to-noise ratio) and a real-time Fourier transformation with a linear dynamic range exceeding 60 dB has been performed. A programmable correlator and a programmable filter have been demonstrated that use the newly discovered acousto-photorefractive memory effect. This effect is based on a nonlinear interaction between intense, short-duration laser pulses permanent index-of-refraction pattern corresponding to the SAW signal. An implementation of the triple-product convolver architecture (proposed by Whitehouse et al.) for perform-ing either a long one-dimensional or a two-dimensional discrete Fourier transform can be obtained by combining an acousto-optic convolver with many CCD chirp-Z transform modules. This triple-product convolver would have extremely rapid data handling capability and large dynamic range, and would be useful for applications such as "w-k" beamforming for sonar signal process-ing. Further, a programmable 1-, 2-, 3-dimensional beamformer with a one second update capability may be feasible if the acousto-photorefractive memory effect is used to store SAW signals corresponding to the position of nonstationary sensors.
N. J. Berg, N. J. Berg, J. N. Lee, J. N. Lee, M. W. Casseday, M. W. Casseday, } "Acousto-Optic Implementation Of Real- And Near-Real-Time Signal Processing," Optical Engineering 18(4), 184420 (1 August 1979). https://doi.org/10.1117/12.7972398 . Submission:

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