Share Email Print

Proceedings Paper

Modeling low-coherence enhanced backscattering (LEBS) using photon random walk model of light scattering
Author(s): Hariharan Subramanian; Prabhakar Pradhan; Young L. Kim; Yang Liu; Vadim Backman
Format Member Price Non-Member Price
PDF $14.40 $18.00
cover GOOD NEWS! Your organization subscribes to the SPIE Digital Library. You may be able to download this paper for free. Check Access

Paper Abstract

Interference effects caused due to the coherent waves traveling in time reversed paths produces an enhanced backscattering (EBS) cone, which is known to be inversely proportional to the transport mean free path length (ls*) of a scattering media. In biological media, ls* (0.5-2mm) >> wavelength λ, results in an extremely small (~0.0010) angular width of the EBS cone making the experimental observation of such narrow peaks to be difficult. Hence, we developed a low coherence enhanced backscattering (LEBS) technique by combining the EBS measurements with low spatial coherence illumination and low temporal coherence detection. Low spatial coherence behaves as a spatial filter preventing longer path lengths and collects photons undergoing low orders of scattering. The experimental angular width of these LEBS peaks (~0.30) are more than 100 times the width of the peak predicted by conventional diffusion theory. Here we present a photon random walk model of LEBS cones obtained using Monte Carlo simulation to further our understanding on the unprecedented broadening of the LEBS peaks. In general, the exit angles of the scattered photons are not considered while modeling the time reversed interference phenomenon in diffusion regime. We show that these photon exit angles are sensitive to the low orders of scattering, which plays a significant role in modeling LEBS peaks when the spatial coherence length of the light source is much smaller than ls*. Our results show that the model is in good agreement with experimental data obtained at different low spatial coherence illumination.

Paper Details

Date Published: 3 March 2006
PDF: 9 pages
Proc. SPIE 6085, Complex Dynamics and Fluctuations in Biomedical Photonics III, 608503 (3 March 2006); doi: 10.1117/12.646868
Show Author Affiliations
Hariharan Subramanian, Northwestern Univ. (United States)
Prabhakar Pradhan, Northwestern Univ. (United States)
Young L. Kim, Northwestern Univ. (United States)
Yang Liu, Northwestern Univ. (United States)
Vadim Backman, Northwestern Univ. (United States)

Published in SPIE Proceedings Vol. 6085:
Complex Dynamics and Fluctuations in Biomedical Photonics III
Valery V. Tuchin, Editor(s)

© SPIE. Terms of Use
Back to Top