Litographic patterning of non-planar surfaces

The integration of multiple optical functionalities into a single (ideally monolithic) hybrid element allows the downsizing of complex high-performance optical systems. As an example, Offner type imaging spectrometers make use of a reflective grating structure at a spherical shaped surface. An ultra-precision machined surface has been patterned by direct-writing optical lithography and a subsequent etching transfer using a reactive plasma process. It became part of the DESIS space mission.

Atomic Layer Deposition of Antireflection Coatings and Bandpass Filters

Conformal coatings are enabled by atomic layer deposition (ALD). This deposition method is based on cyclic, self-limiting reactions of precursors at the substrate surface. It allows precise thickness and composition control of thin films on arbitrarily shaped optics, which is a prerequisite for high optical performance. Interference multilayer optical coatings such as antireflection coatings and narrow bandpass filters on strongly curved optical lenses and dome components are presented.

Direct bonding of diffraction gratings and prisms

The demands on spectroscopic systems are immense. Experts at Fraunhofer IOF have developed a technology that even thick and rigid components, such as prisms, can be connected, so spectrometers can be built even more compact and robust in the future. The method is based on the formation of covalent oxygen bonds between different glass surfaces. This makes the PGP (prism-grating-prism) system suitable for other vacuum applications, for example precision optics or highly sensitive interferometers.