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Proceedings Paper

Modeling of a focused beam in a semi-infinite highly scattering medium
Author(s): Andreas Tycho
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Paper Abstract

In recent years, models based on the "Extended Huygens-FresnelÓ principle has been applied in the description of light propagation in tissue. This principle was originally developed for light propagation through aerosols and clear air turbulence. An adaptation of this principle to tissue for the analysis of Optical Coherence Tomography (OCT) systems is advantageous, because of the convenient description of complex optical systems through implication of the ABCD-matrix formalism, and because -contrary to transport theory and diffusion theory- the phase of the light can be modeled. OCT is often combined with con focal microscopy by focusing the probing beam. It is therefore interesting to gauge the performance of the Extended-Huygens Fresnel theory for a geometry with a focused gaussian beam against a (for tissue) more well established model such as diffusion theory. A new model of a focused beam in a semi-infinite slab of scatterers using the diffusion theory is presented here. The model is developed using a GreenÕs function and a Hankel transform. The performance of both models is gauged against Monte Carlo simulations for a medium with low loss and highly forward scattering particles, which is typical of tissue. The model based on diffusion theory utilizes an exponential phase function, and the implication of using this phase function instead of the traditionally used Henyey-Greenstein phase function is investigated. Finally, reasonable qualitative agreement between the three models is shown and discussed.

Paper Details

Date Published: 15 July 1999
PDF: 12 pages
Proc. SPIE 3597, Optical Tomography and Spectroscopy of Tissue III, (15 July 1999); doi: 10.1117/12.356801
Show Author Affiliations
Andreas Tycho, Technical Univ. of Denmark (Denmark)

Published in SPIE Proceedings Vol. 3597:
Optical Tomography and Spectroscopy of Tissue III
Britton Chance; Robert R. Alfano; Bruce J. Tromberg, Editor(s)

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