Time-dependent photon migration using path integrals

We present an approach to the problem of light propagation in turbid media based on the path integral formalism. The method of analysis provides solutions to the time-dependent equation of radiative transfer for a number of cases for which known approximations, including the diffusion approximation, are not applicable. The theory and experiments show that trajectories of photon traversing a turbid medium cluster around a well defined, time-resolved path called a classical path. This concept is a powerful tool, and it provides physical insight into optical propagation in turbid media.