SPACE-TIME IMAGING OF TRANSIENT ULTRASOUND FIELDS

A new technique for imaging the full space-time complexity of transien t ultrasound fields is presented. The theoretical basis of the method is developed in terms of the directivity spectrum, which is a generali zation of the angular spectrum. The input field measurement set, acqui red at a single distance from the transducer, consists of spatial proj ections of the field, which are directly measured with a large apertur e hydrophone, as described in the text. The method compares very favor ably with the angular spectrum approach and is devoid of evanescent wa ves. It allows computed pulse propagation over extended ranges, even i n the backward direction from the measurement location. (C) 1997 John Wiley & Sons, Inc.