Characteristics of the optical regime in the volume of a semiinfinite layer of diffusely scattering medium under illumination by a directed beam with finite aperture

The absolute values and distribution of the spatial illuminance in the volume of a semiinfinite layer of a light-scattering medium illuminated with a directed beam with finite aperture are calculated by the Monte Carlo method. The characteristics of the optical regime in the layer under conditions of multiple scattering are studied. Approximate expressions are obtained for engineering calculations of the spatial illuminance from the known values of the refractive index and coefficient of diffuse reflection of the layer.