Use of a laser beam with an oblique angle of incidence to measure the reduced scattering coefficient of a turbid medium

Abstract

A simple and quick approach is used to measure the reduced scattering coefficient (μ_s') of a semi-infinite turbid medium having a much smaller absorption coefficient than μ_s'. A laser beam with an oblique angle of incidence to the medium causes the center of the diffuse reflectance that is several transport mean-free paths away from the incident point to shift away from the point of incidence by an amount Δx. This amount is used to compute μ_s' by μ_s' = sin(α_i)/(nΔx), where n is the refractive index of the turbid medium divided by that of the incident medium and α_i is the angle of incidence measured from the surface normal. For a turbid medium having an absorption coefficient comparable with μ_s', a revision to the above formula is made. This method is tested theoretically by Monte Carlo simulations and experimentally by a video reflectometer.

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