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.

• Received 6 January 1995

DOI:https://doi.org/10.1103/PhysRevE.51.6134