Effects of optical variables in a single integrating sphere system on estimation of scattering properties of turbid media

Abstract

This research was aimed at determining the effect of optical variables for a single integrating sphere system, coupled with the inverse adding-doubling method, on estimating the reduced scattering coefficient ( μ s ′ ) of turbid media. Integrating sphere measurements were performed on a total of 36 liquid samples and two solid samples. The results demonstrated that the system had good accuracy, with average errors for estimating absorption coefficient μa (pure absorption) and μ s ′ (pure scattering) of liquid samples being 15.0% and 4.7% over 550–900 nm, compared with the collimated transmittance and empirical equation, respectively. The system also had good reproducibility for μa and μ s ′ , with the coefficients of variation lower than 4%. Sensitivity analysis revealed that the detectable values of μa and μ s ′ were around 0.02 cm−1 and 4.5 cm−1. Entrance and detector port diameters, standard reflectivity and anisotropy factor had a negligible effect on estimating μ s ′ ( μ s ′ (2.8%–35.3%). Hence these variables should be carefully chosen or accurately measured before optical property measurements are carried out. Application examples of the μ s ′ estimation for apple skin and flesh further validated the system performance, indicating that appropriate selection of optical variables could improve the estimation of μ s ′ .