Spectrally-resolved errors in absorption and reduced scattering due to µ _a-µ _s' cross-talk in layered media

Spatially-resolved reflectance (SRR) techniques are essential for in vivo noninvasive optical characterization of biological tissue. Under the common assumption of a single-layer volume to approximate human skin tissue, the long-standing issue of µ_a -µ_s ^' cross-talk warrants a thorough investigation and description of its potentially detrimental effects on the accuracy of measured absorption and reduced scatter. Using a two-layer model built from ex vivo measured porcine optical properties, we use analytical solutions to the radiative transfer equation to obtain calculated reflectance curves, which are fitted with a single-layer model to determine effective optical properties. We demonstrate systematic errors in fitted optical coefficients that display clear dependence on the optical properties of the two-layer medium and the inversion cost function. We provide a guide of the errors that a researcher may expect when performing in vivo optical characterization of biological tissue with SRR methods under the single-layer inverse model.