Photon-induced contamination of optical surfaces is a major obstacle for space-bound laser applications. At Laser-Laboratorium Göttingen, a setup was developed that allows monitoring transmission, reflection and fluorescence of laser-irradiated optical components under well-controlled vacuum conditions, in order to assess their possible optical degradation due to radiation-induced contaminant deposition in orbit. In cooperation with the European Space Agency ESA optical elements for the ADM-Aelolus mission were investigated. In order to perform global wind-profile observation based on Doppler-LIDAR, the satellite ADM-Aelolus will be launched in 2011 and injected into an orbit 400 km above Earth's surface. ADM-Aeolus will be the first satellite ever that is equipped with a UV-laser (emitting at a wavelength of 355 nm) and a reflector telescope. For both high-reflecting mirrors and an anti-reflective coated windows long-term irradiation tests (up to 500 million laser pulses per test run) were performed at a base pressure < 10^-9 mbar, using a XeF excimer laser (λ=351 nm, repetition rate 1kHz). At this, samples of polymers used inside the satellite (insulators for cabling, adhesives, etc.) were installed into the chamber, and the interaction of their degassing with the sample surfaces under laser irradiation was investigated. Optical degradation associated with contaminant adsorption was detected on the irradiated sample sites as a function of various parameters, including pulse repetition rate, view factor and coating material

Date Published: 29 November 2010
PDF: 9 pages
Proc. SPIE 7842, Laser-Induced Damage in Optical Materials: 2010, 78422E (29 November 2010); doi: 10.1117/12.869297

Published in SPIE Proceedings Vol. 7842:
Laser-Induced Damage in Optical Materials: 2010
Gregory J. Exarhos; Vitaly E. Gruzdev; Joseph A. Menapace; Detlev Ristau; M. J. Soileau, Editor(s)