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 optical 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 to the intrusive presence of the transducer. A similar result is confirmed in pulse-echo measurements. Alternatively, no significant effect of the contact transducer on the frequency content of the measured ultrasonic waves is observed. It also appears that the measured attenuation in ultrasound amplitude is primarily due to the loading of the sample by the contact transducer. (C) 1999 Elsevier Science B.V. All rights reserved.