Abstract

New results are reported on the statistics of photon paths in random media. There is evidence that sine of the diffuse photons can propagate along well-defined narrow branches of paths.^1-4 This indicates that not all diffusive photons are equivalent. One should distinguish between properly diffusive photons, pursuing very involved complex trajectories through a medium, and the others, propagating along more definite (most favorable) paths. Snake photons^1,2 propagate nearly forward; direct, the rest, however, strongly deviate from straight-line paths. Some of the later-arriving photons are called "Fermat photons" because they obey the generalized fermat principle (GFP) for turbid media—a counterpart of the conventional Fermat principle for transparent media.

© 1995 Optical Society of America