The activity shall develop and test novel technologies for the alignment, assembly and integration of optical assemblies under vacuum.

Many astronomical space missions observe at wavelengths which are absorbed by the atmosphere, as for example some infrared, ultraviolet or x-ray bands. Especially UV and x-ray optics have very stringent alignment tolerances due to the small wavelengths. Consequently, telescopes and instruments can only be tested at their operational wavelengths under vacuum conditions. Traditional methods for fixing optical elements and subassemblies (eg. gluing, soldering, welding, laser based methods) are executed under atmospheric conditions and by using reference interfaces or other wavelengths to ensure their correct alignment. Being able to perform critical alignment steps under vacuum conditions at the design wavelengths would be the most direct and accurate way and reduce risks associated with indirect alignment methods or using in-flight mechanisms for alignment corrections.The activity shall:(1) Review existing alignment and bonding technologies for optical elements and subassemblies and evaluate their suitability for being used under vacuum conditions including an assessment of the mechanical, thermal and contamination properties of the methods. This shall include a wide range of optics and subassemblies (e.g. size, wavelengths, materials) and technologies (e.g. gluing, soldering, welding, laser based methods).(2) Design test setups and samples for different technologies and perform alignment and assembly tests on different optical samples under vacuum (and under atmosphere as references). This shall include the measurement of the alignment accuracy, the interface strengths, contamination of optical surfaces and their effects at the design wavelength.