Motion effects in scanned acoustic holography

Analytical and experimental results are presented concerning the effects of unwanted motion between the object vaanrdio us elements of an acoustic imaging system duringth e recording of a scanned acoustic hologram using an electronic reference. It is found that the basic lesults are different for motionsi n different directions and that the principal effect on the holograism d istortion of the fringe pattern rather than blurringo f the fringes as in optical holography. Various kinds of distortion for a variety of cases involving a moving ultrasonic point source are discussed. (In addition, the effect on image quality is analyzed for an extended test object that reflects, rather than is the source of, the ultrasonicw aves which constitute the scene beam.) Analytical results are given for the decrease in resolution associated with the different kinds of motion. The approach used here is fundamentally deterministic in nature, as opposed to statistical, and only simple uniform motions an considered.