5C-3 A 40 MHz Linear Array based on a 1-3 Composite with Geometric Elevation Focussing

The fabrication and performance of a high-frequency (40 MHz) linear array is described. A PZT-polymer composite material was fabricated in order to serve as a flexible piezoelectric substrate. The array pattern was created using photolithography to define the electrodes, and ultrasonic wire bonding to make electrical contacts. 256 linear elements were defined with 40-micron pitch. A geometric elevation focus was formed with a 6 mm radius of curvature. The two-way -6 dB bandwidth of the resulting transducer was 50%. The one-way directivity for a single array element was found to be 24 degrees and the -3dB oneway elevation beamwidth was measured as 112 mum