Reverse Monte Carlo Simulations of Light Pulse Propagation Within Three-Dimensional Media

摘要

An ultrashort light pulse inside an absorbing and anisotropically scattering three-dimensional nonhomogeneous medium is considered. The purpose is two fold: to develop an accurate and easily parallelized numerical model to understand the physics of the transport process and to provide a tool with which a direct comparison with measured temporal signals can be made. The ultrashort light pulse propagation is modeled by the reverse Monte Carlo method. The detailed algorithm treating the source integration over a path length that contains nonuniform radiative properties and finite-size collimated source is given. Validation and numerical simulations are presented. It is found that there is a direct correlation between the travel time of ballistic photons in the temporal reflectance signals and the interface location under certain conditions. It is also found that the inversion parameters proposed by earlier research, such as the long-time logarithm slope and pulse-broadening effect, are inadequate for use in the inverse analysis because these parameters do not provide the specificity needed for such use. More study is needed to identify effective inversion parameters.