Characterization of Ultrasonic Immersion Transducers

In any ultrasonic NDE experiment, the distributed field properties of the transducer involved represent an important aspect of the overall measurement process. The normal velocity profile across the active face of the transducer is typically used to characterize these properties. In quantitative NDE applications, a simple parametric form is usually assumed for this profile, such as a rigid piston with either the nominal or so-called active probe diameter taken as the parameter value. It has been shown in related studies that such an approach does not characterize all UT transducers accurately in all measurement situations (particularly nearfield versus farfield locations). Thus a new method for individual transducer characterization is presented herein that is based on reconstructions of the unknown probe velocity profile from measurements of the radiated field