Broad band single crystal transducer for contrast agent harmonic imaging

A broadband single element transducer was constructed from single crystal PMN-PT and tested to determine the feasibility of using this material for simultaneous subharmonic and second harmonic imaging. The transducer consisted of a 1-3 PMN-PT/epoxy composite with two quarter wave matching layers and a backing. The transducer face was spherically curved to yield a 50 mm focal point. The transducer had a center frequency of 5.2MHz and -6 dB bandwidth over 120% ranging from 2.08 MHz to 8.32 MHz, but the response decayed very slowly outside the -6 dB band so that useable bandwidth was estimated to be on the order of 200%. Subharmonic and second harmonic responses will be tested by driving the transducer with a 3.5 MHz 64-cycle tone burst and recording the impedance spectra of harmonics generated by Optison contrast agent dispersed in water. These tests are currently in progress.