Katsuhiro ISHII¹, Izumi NISHIDATE², and Toshiaki IWAI²

¹The Graduate School for the Creation of New Photonics Industries, Hamamatsu 431-1202, Japan
²Institute of Symbiotic Science and Technology, Tokyo University of Agriculture and Technology, Koganei, Tokyo 184-8588, Japan

(Received August 1, 2013; Revised January 6, 2014; Accepted January 29, 2014)

Numerical analysis of optical propagation in highly scattering media is investigated when light is normally incident to the surface and re-emerges backward from the same point. This situation corresponds to practical light scattering setups, such as in optical coherence tomography. The simulation uses the path-length-assigned Monte Carlo method based on an ellipsoidal algorithm. The spatial distribution of the scattered light is determined and the dependence of its width and penetration depth on the path-length is found. The backscattered light is classified into three types, in which ballistic, snake, and diffuse photons are dominant.

Key words: Monte Carlo simulation, multiple scattering, optical coherence tomography, diffuse photons, snake photons