This document summarizes research on modeling optical scattering in the Laser Interferometer Gravitational-Wave Observatory (LIGO) using the Bidirectional Reflectance Distribution Function (BRDF). LIGO contains laser interferometers with test masses that scatter a small amount of light due to imperfections. The BRDF was measured for LIGO's test masses and compared to scattering models. It was found that scattering from the installed test masses was larger than models predicted, likely due to alterations during installation. More work is needed to update models to match the conditions of the installed test masses.