Diffuse photon-remission associated with single-fiber geometry may be a simple scaling of that collected over the same area when under centered-illumination.

ABSTRACT

Robust models for single-fiber reflectance (SFR) are relatively complex [Opt. Lett.45, 2078 (2020)OPLEDP0146-959210.1364/OL.385845] due to overlapping of the illumination and collection areas that entails probability weighting of the spatial integration of photon-remission. We demonstrate, via analytical means for limiting cases and Monte Carlo simulation of broader conditions, that diffuse photon-remission collected by single-fiber geometry may be scaled over the center-illuminated photon-remission. We specify for a medium revealing Henyey-Greenstein (HG) scattering anisotropy that the diffuse photon-remission from a sub-diffusive area of a top-hat illumination is ∼84.9% of that collected over the same area when under a centered-illumination. This ratio remains consistent over a reduced-scattering fiber-size product of µs'dfib=[10-5,100], for absorption varying 3 orders of magnitude. When applied to hemoglobin oxygenation changes induced in an aqueous phantom using a 200 µm single-fiber probe, the center-illumination-scaled model of SFR produced fitting results agreeing with reference measurements.