Large aperture hydrophones for field characterization [ultrasonics]

A well-developed approach towards the measurement of ultrasound fields and the characterization of transducers relies on the use of wideband, pointlike hydrophones. An alternative approach, based on the use of very large aperture hydrophones, is suggested, and it is shown to be valuable in a number of contexts. The notion of the directivity signature is introduced, and it is shown how this may be measured directly with a large aperture hydrophone. The directivity signature is the time-domain equivalent of the full three-dimensional spectrum of the field, which, in turn, is a generalization of the angular spectrum description. The possibility of performing a number of measurements is discussed. In some cases, there are clear advantages over conventional techniques