THERMOELASTIC EXCITATION OF ACOUSTIC-SIGNALS BY A LASER IN SOLIDS WITH A FREE-BOUNDARY

We present the results of theoretical and experimental investigations of the characteristics of ultrasonic pulsed signals excited by lasers under thermoelastic generation conditions, as applied to the possibili ty of using them for ultrasonic inspection of items. The solutions are obtained for signals emitted by single-mode lasers in the Q-modulatio n regime. We have investigated longitudinal, transverse, and surface R ayleigh waves. We have shown that along the normal to the surface of t he target, in metals longitudinal and transverse waves are not radiate d under thermoelastic excitation conditions. We demonstrate that the d irectionality of the radiation of longitudinal and transverse waves is independent of the duration and the mode characteristic of the light pulses, and also the dimensions of the light spot.