Absorption and reduced scattering coefficient estimation in pigmented human skin tissue by experimental colorimetric fitting

This study aims to estimate the optical properties, absorption (mu a), and reduced scattering (mu!s) coefficients of ex vivo human skin through the individual typology angle (ITA) by only using the skin color parameters. Human skin samples were grouped according to their ITA value and measured using a colorimeter for validation. An inte-grating sphere and the inverse adding-doubling algorithm were applied to compute the samples mu a and mu;. The mu a increases as the ITA decreases. An axis swap was performed to generate the mu a versus the ITA for all wavelengths between 500 nm and 800 nm with a spectral resolution of 10 nm. Linearization was performed and a correlation was found. An equation to fit mu a based solely on the ITA values was estimated. The mu; does not change with ITA, but it could be fit with an inverse power law as a function of the wavelength. Both equations have a coefficient of determination (R2) higher than 0.93, indicating a good agreement with our model. An experimental model to estimate the absorption and reduced scattering coefficients of ex vivo human skin through ITA was found. The model has high agreement with the experimental data, with an R2 between 0.932 and 0.997, and these findings may be relevant for photobiomodulation and light treatment applications to estimate the effect of the melanin on the therapy. (c) 2023 Optica Publishing Group