US Patent 11686890 Multi-level diffractive optical element thin film coating

A transmissive optical element may include a substrate. The transmissive optical element may include a first anti-reflectance structure for a particular wavelength range formed on the substrate. The transmissive optical element may include a second anti-reflectance structure for the particular wavelength range formed on the first anti-reflectance structure. The transmissive optical element may include a third anti-reflectance structure for the particular wavelength range formed on the second anti-reflectance structure. The transmissive optical element may include at least one layer disposed between the first anti-reflectance structure and the second anti-reflectance structure or between the second anti-reflectance structure and the third anti-reflectance structure.