Photoacoustic recovery of an absolute optical absorption coefficient with an exact solution of a wave equation.

We describe a new approach to recover an absolute optical absorption coefficient from measured photoacoustic signals based on an exact solution of the wave equation. We present a numerical model to describe the detection of photoacoustic waves by introducing a point spread function of a photoacoustic measuring system. This model is employed in an iterative fitting procedure in order to recover an absolute optical absorption coefficient. In addition, the fitting procedure utilizes the ratios of the amplitudes of the characteristic peaks of photoacoustic signals as the input, as opposed to using the total measured photoacoustic data. Such an arrangement increases computational speed and reduces the influence of signals from neighboring objects. The proposed method is then verified both numerically and experimentally on the gel samples, from which the accuracy is found to be in the range -5.2% to 4.8%.