Ultrasound Transducer Characterization Using Angular Spectrum Backpropagation
This paper presents a measurement method for analyzing the surface velocity patterns of ultrasonic transmitters, based on the angular spectrum backpropagation method of wavefield analysis. With this approach, acoustic propagation between parallel planes is modelled by taking the two-dimensional Fourier transform of the wavefield, multiplying each element in the spatial frequency domain by the appropriate phase factor, and inverse transforming the resultant angular spectrum. The basic method was expanded from the monochromatic case to the wideband pulsed case, which is more typical of diagnostic instrumentation. An experimental system was designed built to measure the acoustic fields from various transducers, including single element and multi-element phased arrays. Results are given for circular planar, circular focussed, and rectangular phase steered transducers. The results demonstrate the method’s ability to reconstruct the surface velocity distributions of complex ultrasonic radiators.
KeywordsAcoustics Hydrophone Lewin
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