It is crucial to take into account the shape and structure of the AgX grains when considering light scattering and absorption in emulsion layers. Most models of light propagation treat photons as corpuscles and grains as spheroids. However, for modern T-grain emulsions this is not a satisfactory approach. Light wave propagation in the vicinity of a grain of arbitrary shape can be calculated from the Maxwell equations of classical electrodynamics, but up until now the computing power required was too great. A new application of multiple-grid algorithms has now been developed that drastically cuts the required computation time from 6 months to less than 10 h for 1 million grid points when solving the equations for a volume element of (2 μm)3. This wave model replaces the MIE model when calculating the cross section of extinction, absorption probability, and angular distribution of light scattering for silver halide grains. Light distribution and internal exposure can be simulated by introducing the layer structure and grain distribution of the real film into the model. Area exposures of up to 0.1 mm2 are possible with an edge exposure to simulate MTF measurements. A method has been developed to remove granularity noise from simulated and measured MTF test scans.
U. Siemen, D. Hertel, "Using a Wave Model to Study Light Propagation in Emulsion Layers Containing Realistically Shaped AgX Grains" in Journal of Imaging Science and Technology, 1999, pp 70 - 78, https://doi.org/10.2352/J.ImagingSci.Technol.1999.43.1.art00009