Knowledge of bidirectional reflectance angular distribution of low reflectivity surfaces is important for predicting
stray light in optical systems. We have performed bidirectional reflectance distribution measurements at wavelengths
of 633 nm and 850 nm for surfaces coated with Z302, a commercial optical coating material widely used in optical
instruments. The bidirectional reflectance properties of these surfaces depend on surface topology characterized by
thickness and roughness parameters. To explain our results, we have employed directional scatter analysis of the
experimental data that can be represented by a linear combination of diffuse, glossy, and specular, components.
Modeling the bidirectional reflectance distribution in the context of a ray-trace can provide important information of
stray light, coated surfaces, and their impact on performance of optical instruments.