Four-flux radiative transfer models have been extensively used to describe reflectance and transmittance (R&T) spectra of light scattering and absorbing (S&A) media. Solutions to the differential equations corresponding to the collimated fluxes are obtained by subsequent application of boundary conditions. Explicit expressions for the collimated R&T of light are reported, when considering a light S&A medium contained between two glass slides, an experimental arrangement which is appropriate for liquid suspensions and viscous matrices containing solid particles. A spectral simulated annealing method is applied to retrieve, from measured R&T spectra of collimated light under normal incident radiation, the scattering and absorption coefficients of the composite medium. First, the accuracy of the method is established by applying it to synthetic collimated R&T data. Secondly, we apply the method to experimental data and use it to determine the S&A coefficients of a layer of TiO2 particles dispersed in a PVP/water matrix.

中文翻译：

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从准直辐射的反射率和透射率光谱中获取的光漫射材料的散射和吸收截面

四通量辐射传递模型已广泛用于描述光散射和吸收 (S&A) 介质的反射和透射 (R&T) 光谱。通过随后应用边界条件获得对应于准直通量的微分方程的解。当考虑包含在两个载玻片之间的轻型 S&A 介质时，报告了光的准直 R&T 的明确表达式，这是一种适用于液体悬浮液和含有固体颗粒的粘性基质的实验装置。应用光谱模拟退火方法，从在法向入射辐射下测得的准直光的 R&T 光谱中检索复合介质的散射和吸收系数。第一的，该方法的准确性是通过将其应用于合成准直 R&T 数据来确定的。其次，我们将该方法应用于实验数据，并用它来确定分散在 PVP/水基质中的一层 TiO2 颗粒的 S&A 系数。