Experiments in acoustic imaging with an isochronal convergence imaging method

Abstract

The method used in this study employs a multi-element transducer. Each transducer element transmits successive cylindrical sound waves at a predetermined interval. During the transmission intervals, all elements receive echos from targets. A digital processor then distributes the amplitude data of these echos on elliptic addresses located in a digital memory system. The relation between sound propagation time and element location determines these elliptic addresses. The resolving power is estimated to be the same as that of a cylindrical transducer measured at the focal point for pulse-echo mode operation. The results of numerical analyses agree well with the estimated values and indicate a high resolving power within the entire imaging plane. A prototype system utilizing this method, containing a 32-element transducer and a mini computer, is used to complete some experimental imaging of stationary targets and the obtained images are discussed.