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Proceedings Paper

Numerical investigation of light-scattering spectra of micro-particles with complicated shapes and textures
Author(s): Xu Li; Zhigang Chen; Allen Taflove; Vadim Backman
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Paper Abstract

It is well recognized that the spectral characteristics of light scattered from living tissue can provide valuable diagnostic information. In order to address the gap in the understanding of light scattering by complex cellular and tissue structures, we developed analytical and computational methods to characterize light scattering signals from irregular shapes. Recently, we investigated the total-scattering-cross-section (TSCS) spectra of complicated geometries based on the finite-difference-time-domain (FDTD) simulations. We found that the TSCS spectra of many inhomogeneous and nonspherical particles can be approximated with those of their best-fitting homogeneous ellipsoidal counterparts, and calculated using a simple formula provided by the equiphase-sphere approximation. Furthermore, we have characterized backscattering spectra of inhomogeneous particles with stochastic distribution of interior refractive index. We have investigated the backscattering signals of a wide range of inhomogeneous micro-particles based on the FDTD method and the Gaussian Random Field model. Our numerical results indicate that, contrary to the TSCS, the backscattering spectrum is sensitive to small structures within a particle, with scales down to tens of nanometers. We also note that the spectroscopic properties of the backscattering signals are directly linked to the coherence length of the interior refractive index distribution, which characterizes the texture of the inhomogeneous particle. The implication of this study is the possibility of using spectroscopic techniques to detect cellular morphological and textural changes within scales several-times smaller than the wavelength.

Paper Details

Date Published: 28 April 2005
PDF: 10 pages
Proc. SPIE 5693, Optical Tomography and Spectroscopy of Tissue VI, (28 April 2005); doi: 10.1117/12.590416
Show Author Affiliations
Xu Li, Northwestern Univ. (United States)
Zhigang Chen, Northwestern Univ. (United States)
Allen Taflove, Northwestern Univ. (United States)
Vadim Backman, Northwestern Univ. (United States)

Published in SPIE Proceedings Vol. 5693:
Optical Tomography and Spectroscopy of Tissue VI
Britton Chance; Robert R. Alfano; Bruce J. Tromberg; Mamoru Tamura; Eva M. Sevick-Muraca, Editor(s)

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