Effect of a clear layer at the surface of a diffusive medium on measurements of transmittance and reflectance

The effect of a clear layer at the surface of a diffusive medium on measurements of reflectance and transmittance has been investigated with Monte Carlo simulations. To quantify the effect of the clear layer Monte Carlo results have been fitted with the solution of the diffusion equation for the homogeneous medium in order to reconstruct the optical properties of the diffusive medium. The results showed that the clear layer has a small effect on measurements of transmittance. On the contrary measurements of reflectance are greatly perturbed and the accurate reconstruction of the optical properties of the diffusive medium becomes almost impossible.