The photoacoustic effect generated by laser irradiation of an isotropic solid cylinder

Abstract

The properties of the photoacoustic effect generated by laser irradiation of an optically thin, isotropic solid cylinder surrounded by a transparent fluid are discussed. Solutions to the wave equation for the displacement potential in the solid and the surrounding fluid are found, which, together with the conservation equations for acoustic waves at the solid-fluid interface, give the frequency domain pressure. The response of the solid cylinder to a delta function heating pulse is obtained by Fourier transformation of the frequency domain expression. The photoacoustic waveform generated by a short radiation pulse is shown to depend on the radius of the cylinder, the density and longitudinal sound speed of the cylinder relative to those in the surrounding fluid, and the transverse-to-longitudinal sound speed ratio for the solid. Experiments with solid rods irradiated by a Q-switched laser are reported.