Precise determination of the optical properties of turbid media using an optimized integrating sphere and advanced Monte Carlo simulations. Part 2: experiments

Based on theoretical investigations of the light propagation within an integrating sphere, we developed an accurate method to determine the optical properties of scattering media using an integrating sphere-based setup. The method takes into account the exact sphere geometry as well as the different angular distributions of the reflected and transmitted light from the sample and the calibration standard. We tested our novelties successfully in theory with Monte Carlo simulations and in practice using a 3D printed and professionally coated integrating sphere. As a result, we were able to determine precisely the effective scattering coefficient, mu(s)', and the absorption coefficient, mu(a), between 400 nm and 1500 nm in a range of mu(a) = 1e-3 mm(-1) to 10 mm(-1) and mu(s)' = 0.2 mm(-1) to 100 mm(-1). Usually, the accuracy was around 1% for mu(s)' and around 3% for mu(a) for turbid phantom media with an optical thickness tau = mu(s)' d > 1 and a transmittance signal > 0.1%. (C) 2020 Optical Society of America