Ultrasonic transducer with a selectable beamwidth comprising a body of piezoelectric material in the form of an annulus having an outer diameter D and a thickness T. The body has proximal and distal generally planar parallel surfaces and a centrally disposed hole extending therethrough. The body has...http://www.google.fr/patents/US5581144?utm_source=gb-gplus-shareBrevet US5581144 - Miniature, high efficiency dual frequency ultrasonic transducer with selectable beamwidth and apparatus
Miniature, high efficiency dual frequency ultrasonic transducer with ...
