Before this update, the single scattering model calculated and integrated the differential cross section at a distance = film thickness in the presence of absorption in the system. This led to the transport length becoming dependent on the thickness in an absorbing system, which does not make physical sense.
I originally did this because the reflectance uses the ratio of the detected cross section (found by integrating the diff cross section at detection angles smaller than 180 deg) over the total cross section, and we find near field effects when we integrate at the surface of the scatterer over only part of the sphere. These cancel out when we integrate over the full sphere. Therefore I chose an arbitrary distance = thickness, and of course the absorption will affect the magnitudes of the detected and total cross sections, but we only care about their ratio, which does not depend on the integration distance. However, the transport length and g only use the total cross section (and not a ratio), so I updated the code such that the total cross section is calculated at the surface of the scatterer when there is absorption only for the transport length and g.
Before this update, the single scattering model calculated and integrated the differential cross section at a distance = film thickness in the presence of absorption in the system. This led to the transport length becoming dependent on the thickness in an absorbing system, which does not make physical sense.
I originally did this because the reflectance uses the ratio of the detected cross section (found by integrating the diff cross section at detection angles smaller than 180 deg) over the total cross section, and we find near field effects when we integrate at the surface of the scatterer over only part of the sphere. These cancel out when we integrate over the full sphere. Therefore I chose an arbitrary distance = thickness, and of course the absorption will affect the magnitudes of the detected and total cross sections, but we only care about their ratio, which does not depend on the integration distance. However, the transport length and g only use the total cross section (and not a ratio), so I updated the code such that the total cross section is calculated at the surface of the scatterer when there is absorption only for the transport length and g.