Simultaneous Reconstructions of Absorption Density and Wave Speed with   Photoacoustic Measurements
  In this paper we propose an approach for \emph{simultaneous} identification of the \emph{absorption density} and the \emph{speed of sound} by photoacoustic measurements. Experimentally our approach can be realized with sliced photoacoustic experiments. The mathematical model for such an experiment is developed and exact reconstruction formulas for both parameters are presented. 
Andreas Kirsch and Otmar Scherzer
math.AP