Instantaneous beamwidth measurements of an electrohydraulic lithotripter

Abstract

Acoustic field measurements of electrohydraulic lithotripters (EHL) are typically conducted with single-element hydrophones and are subject to spatial averaging errors because the spark source location varies from shock to shock. Linear hydrophone arrays provide a means of obtaining the instantaneous sound field of EHLs and a more detailed understanding of EHL sound fields. Here, 20-element hydrophone arrays were used to study the variability of the instantaneous acoustic field of an experimental EHL. Calibrated arrays were placed at the geometric focus of an EHL and exposed to as many as 1500 shock waves using excitations of 14, 17 and 20 kV. Instantaneous data were acquired from all 20 hydrophone elements and then were processed for beamwidth, peak pressure location, and peak pressure. Instantaneous beamwidths were found to be smaller than when using a single-element hydrophone approach and peak pressures were observed to vary more as the excitation voltage increased.