Performance of a Linear Array Transducer of Vinylidene Fluoride Trifluoroethylene Copolymer

Abstract

A 5-MHz 64-element linear array transducer composed of vinylidene fluoride and trifluoroethylene copolymer (P(VDF-TrFE)) has been developed and its performance studied. The transducer has high resolution in both lateral and depth directions and has energy conver- sion efficiency high enough to be used for practical applicalions. The electroacoustic conversion loss (CL) is 6 dB at 5 MHz, and the pulse- echo ring-down period at -20 dB is 1.0 PS. These experimental values are in good agreement with theoretical ones calculated with Mason's equivalent circuit in which the internal losses of a piezoelectric material are taken into account. The ultrasonic field distribution from the array is also in good agreement with the simulations obtained using a numer- ical Huygens' wavelet approach for pulse waves. The maximum cross coupling voltage between the nearest neighbor elements is len percent of the driving voltage. This degree of cross coupling does not appreci- ably degrade the ultrasonic field distribution. A medical echogram taken with this transducer is shown. Its lateral and depth resolutions nn the focal plane are 1.5 mm and 0.75 mm, respectively.