Modeling low-coherence enhanced backscattering (LEBS) using photon random walk model of light scattering

Hariharan Subramanian*, Prabhakar Pradhan, Young L. Kim, Yang Liu, Vadim Backman

*Corresponding author for this work

Research output: Chapter in Book/Report/Conference proceedingConference contribution

1 Scopus citations

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 (l s*) of a scattering media. In biological media, l s* (0.5-2mm) ≫ wavelength λ, results in an extremely small (∼0.001 0) 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 (∼0.3 0) 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 l s*. Our results show that the model is in good agreement with experimental data obtained at different low spatial coherence illumination.

Original languageEnglish (US)
Title of host publicationProceedings of SPIE - The International Society for Optical Engineering
DOIs
StatePublished - 2006
EventComplex Dynamics and Fluctuations in Biomedical Photonics III - San Jose, CA, United States
Duration: Jan 21 2006Jan 24 2006

Publication series

NameProceedings of SPIE - The International Society for Optical Engineering
Volume6085
ISSN (Print)0277-786X

Other

OtherComplex Dynamics and Fluctuations in Biomedical Photonics III
CountryUnited States
CitySan Jose, CA
Period1/21/061/24/06

Keywords

  • Exit angles
  • Low coherence enhanced backscattering
  • Monte Carlo simulation
  • Spatial coherence
  • Transport mean free path

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Computer Science Applications
  • Applied Mathematics
  • Electrical and Electronic Engineering

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