A Novel Technique for Imaging Pulsed Ultrasound Fields

Abstract

Conventionally, a knowledge of the acoustic field is gained via point-to-point measurements performed with a point hydrophone, usually in a water bath. A complete knowledge of the field is then comprised of a four dimensional fonction, p(r, t). Due to the large number of measurements required, it is convenient to restrict data acquisition to a subset of points, usually acquired in a plane. This measurement set, combined with some appropriate theory (conventionally based on the angular spectrum formalism) allows subsequent prediction of the field at other spatial locations. A number of problems arise in obtaining a general measurement knowledge of the field. The hydrophone may change the field it is measuring (particularly in the very near field). The field varies rapidly at some spatial locations. Point hydrophones are imperfect devices. No easy predictive quality exists, either at other spatial locations, or within other media.