A new theoretical approach to photoacoustic signal generation

From the various mechanisms of photoacoustic (PA) signal generation, the one due to local thermal expansion in aqueous media is treated here in detail. This mechanism is also referred to as thermoelastic PA signal generation. A new physical explanation of the spherical PA profile is presented, from which the signals generated by other source geometries and temporal profiles can be deduced. The characteristic PA signal profiles are discussed for some fundamental and practical source geometries. Also the PA signal attenuation and deformation due to viscous and thermoelastic losses is discussed. The analytic result for the transient generated by a spherical Gaussian spatiotemporal PA source is presented. Experimental PA signals are shown for several geometries and source diameters.