Figure 2

Time-resolved reflectance from the two-layered scattering medium with upper layer thickness of l = 2 mm and a refractive index of n _m  = 1.4 due to an infinitely short, perpendicularly incident light pulse with a spatial Gaussian beam profile. The beam radius is ρ _w  = 0.5 mm and the source-detector separation ρ = 2 mm. The refractive index of the surrounding medium is n ₀ = 1.0. Already for N ≥ 3, a good agreement between the Monte Carlo simulation and the P _N solution is observed. For the Monte Carlo simulation 10¹¹ photons were calculated.