Experimental observation of the intrusive effect of a contact transducer on ultrasound propagation

This paper presents experimental observations of the influence of a contact transducer on ultrasound measurements in materials. Through-transmission o ptical detection of the ultrasonic waves at the transducer/sample interface shows an amplitude attenuation of the order of 1.6 dB (peak-to-peak) due t o the intrusive presence of the transducer. A similar result is confirmed i n pulse-echo measurements. Alternatively, no significant effect of the cont act transducer on the frequency content of the measured ultrasonic waves is observed. It also appears that the measured attenuation in ultrasound ampl itude is primarily due to the loading of the sample by the contact transduc er. (C) 1999 Elsevier Science B.V. All rights reserved.