Acoustical Reconstruction of Holograms, and Their Potential Use

Abstract

Extensive work has been performed to date in coherent optical processing. Coherent acoustic processing, on the other hand, has not progressed as far as its coherent optics counterpart, although it has identical operational capabilities. Some progress had been reported earlier¹ in the development of acoustical holographic matched filters, but the published results were not definitely positive. Before now, one of the major factors hindering the development of acoustic processing techniques was the lack of a good acoustic hologram meant to operate directly in an acoustic field. In the past, the detected acoustic holographic information has invariably been used to generate a photographic transparency (of reduced size) which reconstructed a visible image upon irradiation with laser light. Usually, in the conversion process, the image quality suffered because of the orders of magnitude difference between the acoustical and optical wavelengths.