Behavior of laser-induced ultrasonic waves radiated from a wet surface. Part I. Theory

This article deals with the directivity analysis of laser-generated ultrasound irradiated from a wet surface. A mathematical model is developed to take into account the wet surface condition, which is described by nonuniform load distribution on the illuminated surface. In particular, the free surface of an elastic half-space loaded by a time-harmonic normal traction distributed elliptically on a circular source area is considered. The solutions are obtained by using the Bessel–Fourier transformation and evaluating the transform integrals asymptotically. The results are presented for various laser beam diameters and ultrasonic frequencies.