Optical Properties of Diffractive Anti-Reflective Gratings on Curved Surfaces: Fabrication and Testing

Zero-order gratings (ZOGs) are known to theoretically show perfect anti-reflective properties. However, in order to replace classical interference thin-film anti-reflex coatings such ZOGs should be applicable to standard optical elements such as e.g. spherical lenses. For most applications in the VIS and NIR duty cycle and etch depth should be in the order of 200 – 300 nm. Fabrication as well as testing and characterisation of such kind of gratings, especially with respect to convex curved surfaces, require new approaches. The presentation shows the fabrication, testing and characterisation procedure of directly etched ZOGs in standard spherical glass lenses.