THE PHOTOACOUSTIC EFFECT GENERATED BY LASER IRRADIATION OF AN ISOTROPIC SOLID CYLINDER

The properties of the photoacoustic effect generated by laser irradiat ion of an optically thin, isotropic solid cylinder surrounded by a tra nsparent fluid are discussed. Solutions to the wave equation for the d isplacement potential in the solid and the surrounding fluid are found , which, together with the conservation equations for acoustic waves a t the solid-fluid interface, give the frequency domain pressure. The r esponse of the solid cylinder to a delta function healing pulse is obt ained by Fourier transformation of the frequency domain expression. Th e 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 flui d, and the transverse-to-longitudinal sound speed ratio for the solid. Experiments with solid rods irradiated by a Q-switched laser are repo rted.