A backward Monte Carlo estimator for the multiple scattering of a narrow light beam

A backward Monte Carlo estimator is derived for the multiple scattering of a narrow light beam of arbitrary spatial distribution incident on a plane parallel layer. A means of obtaining an error estimate which provides an upper bound on the actual error is suggested. The intuitively clear result that the higher order intensities asymptotically approach each other for all optical radii was observed. It is observed that at reasonably modest optical distances from the beam, consideration of only the first or second orders of scatter in the evaluation of the diffuse light field will lead to erroneous results. Copyright (C) 1996 Elsevier Science Ltd