Theoretical and Experimental Investigations of Broadband Thermoelastically Generated Ultrasonic Pulses

A New Method for Calculation of Laser-Generated Ultrasound Pulses

“…The calculated signal is similar to that found by Doyle [6], in an approximate 3-D model; Schliechert et: al. [7] have reported a positive precursor, but without detailed waveforms; a positive displacement was also found by Telschow and Conant in a 1-D model (in which u12 andu21 are absent). These authors have all attributed the signal to the finite dimension of the thermal source resulting from thermal diffusion.…”

“…The need to make these applications quantitative requires a theoretical model which: 1) is based on fundamental principles; 2) allows the Usf' of realistic sample and source properties; and 3) is readily usable by the research community without a major computational development effort. Doyle [6] and Schliechert et al [7] have described approaches which meet the first two criteria, but which are very computation-intensive. We will describe and illustrate a new formulation [8] which meets all three criteria.…”

“…Experimental measurements (see reviews by Hutchins [1] and Hutchins and Tam [3]) are in good agreement, except for the small, positive "precursor" (menti_oned above), the source·of which has not been certain. Doyle [6], Schli.echert et al [7], and Telschow and Conant [lS] have attributed this precursor to the finite source dimensions arising from thermal diffusion; however, see below.…”