Laser excitation of surface wave motion

A simplified analysis of surface wave generation by laser irradiation of a homogeneous, isotropic, linearly elastic body is presented. The thermoelastic process of expansion of a surface element is examined, and a direct derivation of equivalent mechanical surface loading is presented. A novel representation of surface wave motion is given in terms of a single-wave potential for a carrier wave propagating on the free surface. Finally, for time-harmonic laser irradiation the elastodynamic reciprocity theorem is used to relate the generated surface wave motion to a virtual surface wave, which leads to a straightforward analytical determination of the generated surface waves for the cases of laser line- and point-focused illumination. The surface-wave pulses for pulsed irradiation are obtained by Fourier superposition. For the line-focus case the surface-wave pulse is proportional to the laser pulse, while for point-focus illumination the surface-wave pulse consists of a principal pulse followed by a smaller pulse of opposite sign. (C) 2003 Elsevier Ltd. All rights reserved.