Abstract

We have built and evaluated two acoustooptic processor architectures for real-time synthetic aperture radar image formation. Both architectures employ space integration using an acoustooptic device in one dimension (range) and a charge coupled device operating in the time delay and integrate mode for processing in the other dimension (azimuth). The two architectures eliminate unwanted bias terms and provide true complex or magnitude squared imagery. The first approach uses multiple optical paths to accumulate unwanted bias terms for subtraction. By decomposing the complex image into three components which are then combined, the real and imaginary portions of the original complex image are obtained and the bias terms are eliminated. In the second approach a spatial carrier is introduced into the azimuthal dimension prior to processing. The optically processed imagery is separated from the bias terms by the carrier. Postprocessing can then remove the carrier and obtain complex imagery via quadrature demodulation or envelope detection. Imagery obtained experimentally using both techniques is presented. A comparison of these techniques is performed in terms of image quality, system complexity, and use in real-time processing.

© 1988 Optical Society of America