Precision Glass Molding of infrared optics with anti-reflective microstructures
Highly precise infrared lenses are used in a broad range of optical systems such as night visions, thermal imaging or gas sensing. As most infrared materials (e.g. Germanium, Chalcogenide glass) suffer from high Fresnel reflection losses, the use of anti-reflective coatings is state of the art to overcome this issue. An alternative approach is the implementation of anti-reflective microstructures into molded infrared lenses. This shortens the process chain and enables many advantages for example regarding the monolithic optics design. Precision Glass Molding (PGM), a replicative manufacturing technology, allows the macroscopic lens molding and the replication of surface microstructures to be carried out simultaneously. While PGM is an established process for manufacturing glass optics in general, there is a lack of knowledge regarding the replication of microstructures. This leads to the necessity to further investigate the PGM process chain for molding microstructures. The current paper addresses the process chain of manufacturing anti-reflective optics by precision glass molding. Process simulations are presented by a multiscale approach. In order to prevent wear, a suitable anti-adhesive coating system for molding tools with regard to the special requirements of microstructured surfaces is introduced. The results of the molding experiments highlight the importance of a multiscale simulation approach and demonstrate the stability of the anti-reflective microstructure.