13 March 2015 Use of extended source model to predict spatially resolved diffuse reflectance close to the source for semi-infinite medium
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Abstract
Under the assumption of high scattering and weak absorbing media, diffusion approximation holds in the radiative transport equation to model propagation of light. Diffusion approximation is valid deep inside the medium, not near the boundary. So, we need to implement accurate boundary conditions. Diffuse reflectance close to the source, majorly, depends on the source model inside the medium and boundary conditions used to derive the analytical solution. We have implemented partial current boundary condition and extrapolated boundary condition with extended isotropic source (exponentially decaying) model. Our model predicts diffuse reflectance close to the source at distance less than one mean free path is more accurate than the other methods. Monte-carlo simulation is the standard model to provide diffuse reflectance close to source most accurately. In this report, partial current, extrapolated boundary condition and a unified boundary condition have been compared for accuracy at different regions from the source. It is found that different boundary conditions work in different regimes and the relative error is less with extended source compared to point source.
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Pankaj Singh, Prabodh Kumar Pandey, Asima Pradhan, "Use of extended source model to predict spatially resolved diffuse reflectance close to the source for semi-infinite medium", Proc. SPIE 9321, Optical Interactions with Tissue and Cells XXVI, 93210W (13 March 2015); doi: 10.1117/12.2080694; https://doi.org/10.1117/12.2080694
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