Differential optical spectroscopy for absorption characterization of mono & two-layered scattering media

Diffuse reflectance techniques are commonly used to characterize the optical properties of various biological tissues in the visible and NIR spectral ranges. Nevertheless a sharp determination of local chromophores concentration in turbid media is usually difficult to obtain because of the nonlinear dependence of the reflected light intensity as a function of scattering and absorption coefficients. The proposed technique of this paper allows to determine absorbent compounds concentration ratios in a turbid medium from three reflectance spectra, measured for source-detector distances inferior to 1 cm. This method is validated in the visible range in case of typical biological absorption and reduced scattering coefficients. Two- layered scattering media are also investigated.