A 2-DIMENSIONAL ARRAY FOR B-MODE AND VOLUMETRIC IMAGING WITH MULTIPLEXED ELECTROSTRICTIVE ELEMENTS

A 2:1 multiplexed 2-D array has been developed that has a sparse eleme nt pattern designed for real time volumetric imaging and an alternate element pattern designed for B-mode imaging. For volumetric imaging, a small aperture was used to provide a wide transmit beam, allowing mul tiple beams to be received simultaneously. For B-mode imaging, a large r aperture with a more narrow transmit beam was used to improve image quality. Sparse random element patterns were evaluated by beamplot and cyst image simulations. Using the alternate element pattern for B-mod e imaging, simulated cyst contrast was improved by 28 %. The multiplex ed transducer was fabricated using an electrostrictive material in whi ch array elements were activated and deactivated by a de bias field. T he transducer had a 3.4 MHz center frequency with 46 % bandwidth, whic h was consistent with KLM simulations. The high dielectric constant of the electrostrictive material resulted in an element clamped capacita nce of 14.3 pF versus 2 pF for a convention PZT element. An output off isolation of -35 dB was measured for transmit and -61 dB for receive. The array was integrated with the volumetric scanner and used to make real time images oi a cyst phantom. The images showed improved cyst c ontrast using the alternate aperture for B-mode imaging. Copyright 199 8 by Dynamedia, Inc.