The Henyey-Greenstein model describes the angular distribution of light scattered by small particles. This model has been applied to numerous situations, ranging from the scattering of light by biological tissue¹ to scattering by interstellar dust clouds². In this model, the angular distribution of scattered light is given by:



The parameter g characterizes the distribution: for g = 0, the model describes a material with a uniform probability of scattering at all angles, but as g approaches unity the distribution becomes highly peaked around q = 0 degrees. q is defined as the angle of the scattered ray with respect to the specular ray; q = 0 degrees refers to scattering along the specular ray in the forward direction, and q = 180 degrees to scattering along the specular ray in the backward direction.