# Oblique-incidence fiber-optic reflectometry for measuring absorption and scattering in turbid media

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 Title: Oblique-incidence fiber-optic reflectometry for measuring absorption and scattering in turbid media Lin, Shao-Pow Tittel, Frank K. Master of Science thesis Oblique-incidence, fiber-optic reflectometry is a simple and accurate method for measuring the absorption and reduced scattering coefficients, $\mu\sb{a}$ and $\mu\sb{s}\sp\prime ,$ of semi-infinite turbid media. Obliquely incident light produces a spatial distribution of diffuse reflectance that is not centered about the point of light entry. The shift in the center of diffuse reflectance is related to the medium's diffusion coefficient, D. We developed a fiber-optic probe to deliver light obliquely and sample the profile of diffuse reflectance. From a relative profile, we measure D, deduce the effective attenuation coefficient, $\mu\sb{eff},$ then calculate $\mu\sb{a}$ and $\mu\sb{s}\sp\prime .$ This method was verified with Monte Carlo simulations and tested on tissue phantoms. Measurements at 632.8 nm were accurate to within 5% for D and $\mu\sb{eff},$ resulting in 10% and 5% accuracy for $\mu\sb{a}$ and $\mu\sb{s}\sp\prime .$ In addition, $\mu\sb{a}$ and $\mu\sb{s}\sp\prime$ spectra were deduced from wavelength-resolved measurements of the diffuse reflectance from a white light source. Lin, Shao-Pow. (1997) "Oblique-incidence fiber-optic reflectometry for measuring absorption and scattering in turbid media." Masters Thesis, Rice University. http://hdl.handle.net/1911/17106. http://hdl.handle.net/1911/17106 1997