Ultrasonic Waveforms in Metal Plates Using Laser Generation and Emat Detection

Abstract

Standard ultrasonic inspection schemes utilize piezoelectric ultrasonic transducers, which are applied either directly to the surface of the sample under test or used as part of an immersion technique. The latter may be inconvenient, whereas the former is dependent on a satisfactory coupling of the transducer with the specimen. These approaches are also inapplicable to inspection at elevated temperatures or in hostile environments, and to samples having surfaces which are rough or which have extensive coatings or oxide layers. The situation is further aggravated when reproducible, wide-band measurements are necessary, especially when a consistent transducer/specimen bond cannot be guaranteed.