A constant beamwidth transducer for ultrasonic applications

A new class of transducers which produce uniform wide beams (/spl sim/20 degrees) at ultrasonic frequencies (/spl sim/1-2 MHz) are being developed by the US Navy for ultrasonic applications. These transducers will provide a wide illuminated field of view for 2-dimensional ultrasonic imaging arrays. The design features a larger volume of active material, relative to conventional planar designs, which allows the application of higher drive fields. The prototype described in this article was driven to 200 VRMS and produced a sound pressure of 203 (dB re 1/spl mu/Pa at 1m) at a frequency of 2.0 MHz. The details of the ultrasonic constant beamwidth transducer design, its fabrication, and measured performance are presented. The transducer described will soon be incorporated into the Navy's Underwater Sound Reference Division Transducer Standards Loan Program.