THEORETICAL AND EXPERIMENTAL METHODS TO EVALUATE ULTRASONIC TRANSDUCERS FOR INSPECTION AND DIAGNOSTIC APPLICATIONS

Ultrasonic transducers for nondestructive inspection and for medical diagnosis are built as self-contained units to be held by hand or in fixtures. They radiate into solids or into liquid baths, and receive signals propagated through these media. The transducers are encased and have protective layers over their radiating piezoelectric elements. To achieve depth resolution, damping backings are bonded to the piezoelectric elements to generate broad bandwidths and hence short impulse responses. These transducers have been analyzed theoretically by Sittig as electromechanical transmission lines. In this paper, Sittig's program is used to calculate the time and frequency response of several transducer configurations with families of values for their electromechanical parameters. Experimental methods are summarized and presented for the evaluation of transducers. It appears that there is sufficient difference between everyday practice and the present state of the art (both theoretical and experimental) to yield opportunities for significant improvements in transducer fabrication and testing. Copyright © 1979 by The Institute of Electrical and Electronics Engineers, Inc.