Scanned Acoustic Holography

Abstract

The initial and perhaps primary appeal of acoustical holography as a technique for imaging is that it circumvents the problem of the design and use of lenses. Relative to optical holography, this leaves the problem of replacing the photographic plates used as a detector with detectors more suitable for sensing and recording an acoustical hologram. Several suitable detectors have been devised^1–6 but perhaps the most obvious method for recording the acoustical hologram is the method whereby a point-like receiver is scanned over a plane in the zone of interference between two beams of ultrasound, one of which has interacted with the object. The second beam of ultrasound must be coherent with the source of ultrasound used to insonify the object. It must also have a spherical or plane wavefront since this facilitates duplicating the wavefront when an optical source is used to illuminate the hologram and form an image.