Rugate Notch Filters

Rugate notch filters are interference filters that have a deep, narrow rejection band while also providing high, flat transmission for the rest of the spectrum. Rugate notch filters feature superior performance over standard notch filters due to the novel manufacturing process that yields a continuously varying index of refraction throughout the oxide film layers. Because of this process, Rugate notch filters feature low ripple and no harmonic reflections compared to standard notch filters, which are made with discrete layers of materials with different indices of refraction.

Rugate notch filters exhibit a high degree of environmental durability and extremely low wavelength shift at high temperatures. The center wavelength will shift to lower wavelengths when incident light is not collimated or at 0° AOI. Typical applications include laser-based fluorescence and ophthalmic devices.

The construction of each filter consists of a Rugate interference coating on a UV-Grade Fused Silica substrate mounted in an aluminum ring for easy handling.