Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE · 2004 · 45 citations · 8 references
Natural SciencesMaterials EngineeringMaterials ScienceOptical AstronomyOptical MaterialsOpticsCoatingsInfrared TelescopesOptical Thin FilmsSurface CoatingsTelescope OpticsThin Film Optical PropertiesCoating DesignEmissivityEnvironmental Durability Of CoatingsEnvironmental Durability TestingHigh-reflectivity CoatingsOptical CoatingsOptical TelescopesTelescopes
The Gemini telescopes were designed to be infrared-optimized. Among the features specified for optimal performance is the use of silver-based coatings on the mirrors. The feasibility study contracted by Gemini in 1994-1995 provided both techniques and recipes to apply these high-reflectivity and low-emissivity films. All this effort is now being implemented in our coating plants. At the time of the study, sputtering experiments showed that a reflectivity of 99.1% at 10μm was achievable. We have now produced bare and protected silver sputtered films in our coating plants and conducted environmental testing, both accelerated and in real-life conditions, to assess the durability. We have also already applied, for the first time ever, protected-silver coatings on the main optical elements (M1, M2 and M3) of an 8-m telescope. We report here the progress to date, the performance of the films, and our long-term plans for mirror coatings and maintenance.
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