Analysis and Application of the Bi-Directional Scatter Distribution Function of Photonic Crystals

Photonic crystals (PCs) are periodic structures built from materials with different refractive indices repeated at sub-wavelength intervals, which results in unusual optical characteristics, including narrow band laser protection, and zero reflectance and high absorption anomalies. Most of the research into the optical properties of PCs has concentrated only on the small range of wavelengths and angles where these effects occur. To better understand where all light leaving a PC is scattered, a Complete Angle Scatter Instrument was used to analyze the scatter from three Guided Mode Resonance Filters designed for laser protection. In the plane of incidence, measurements of the scatter strength were made for nearly all incident and scattered angles. Reflectance data was also taken out of the plane of incidence for selected incidence angles, showing the directional reflectance over the entire hemisphere. This data was used to modify existing empirically based Bi-directional Scatter Distribution Functions (BSDFs), with the goal of producing a model suitable for scene generation of complex objects coated with a GMRF surface.