Figure 7.

Steady-state spatially resolved fluorescence from the two-layered scattering medium with an upper layer thickness of l = 2 mm. Only the upper layer is fluorescent with a quantum yield of ${\mathrm{\Phi }}_e^{\mathrm{(1)}}=1.0$. The system is illuminated by a Gaussian beam with radius ρ _w = 0.5 mm. The optical properties of the layers were assigned to the excitation wavelength, whereas those of the fluorescence wavelength were chosen to be 20% below their respective excitation counterparts. The phase function and the boundary conditions are identical for both wavelengths. The P ₃ solution already shows a very good agreement with the Monte Carlo simulation. For the Monte Carlo simulation, 8 · 10⁹ Photons were calculated.