Significance: We recently developed a model for the reflectance measured with (multi-diameter) single-fiber reflectance (SFR) spectroscopy as a function of the reduced scattering coefficient μs′, the absorption coefficient μ_a, and the phase function parameter p_sb. We validated this model with simulations.

Aim: We validate our model experimentally. To prevent overfitting, we investigate the wavelength-dependence of p_sb and propose a parametrization with only three parameters. We also investigate whether this parametrization enables measurements with a single fiber, as opposed to multiple fibers used in multi-diameter SFR (MDSFR).

Approach: We validate our model on 16 phantoms with two concentrations of Intralipid-20% (μs′=13 and 21  cm^−  1 at 500 nm) and eight concentrations of Evans Blue (μ_a  =  1 to 20  cm^−  1 at 605 nm). We parametrize p_sb as 10^−  5  ·    (  p₁  (  λ  /  650  )    +  p₂(λ/650)²  +  p₃(λ/650)³  )  .

Results: Average errors were 7% for μs′, 11% for μ_a, and 16% with the parametrization of p_sb; and 7%, 17%, and 16%, respectively, without. The parametrization of p_sb improved the fit speed 25 times (94 s to <4  s). Average errors for only one fiber were 50%, 33%, and 186%, respectively.

Conclusions: Our recently developed model provides accurate results for MDSFR measurements but not for a single fiber. The p_sb parametrization prevents overfitting and speeds up the fit.