  While in standard photoacoustic imaging the propagation of sound waves is
modeled by the standard wave equation, our approach is based on a generalized
wave equation with variable sound speed and material density, respectively. In
this paper we present an approach for photoacoustic imaging, which in addition
to recovering of the absorption density parameter, the imaging parameter of
standard photoacoustics, also allows to reconstruct the spatially varying sound
speed and density, respectively, of the medium. We provide analytical
reconstruction formulas for all three parameters based in a linearized model
based on single plane illumination microscopy (SPIM) techniques.
