Characterization Facility for NDE Transducers

The characterization of NDE transducers involves an assessment of the bidirectional acoustoelectric conversion between electrical and acoustic terminals and an evaluation of the near and farfield radiation patterns. The internal details of the transducer are largely unknown and, consequently, the traditional techniques for analyzing the structures cannot be applied. Instead, the transducer may be characterized .as a hybrid two-port network whose parameters may be determined by relatively simple measurements taken at the electrical port when the acoustic loads are known. The radiation pattern involves measurement only in the region exterior to the transducer. There are several techniques which may be used to accomplish this task. Our aoproach has been to measure the acoustic field in the far-field region and then to reconstruct the field at the face of the transducer. Once we have the field at the transducer, an evaluation of the source may be readily determined from amplitude and phase contour plots or from gray scale or pseudo-color images.