Protected-silver coatings for the 8-m Gemini telescope mirrors

M. Boccas, T. Vucina, C. Araya, E. Vera, C. Ahhee

Research output: Contribution to journalConference articlepeer-review

59 Scopus citations


The twin 8-m diameter Gemini telescopes were designed to use silver-based coatings on the mirrors in order to provide very high reflectivity and ultra-low emissivity for optimal infrared performance. A feasibility study provided both techniques and recipes to apply these thin films, and showed that a reflectivity of 99.1% at 10 μm 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 in an observatory environment. We have also already applied, for the first time ever, protected-silver coatings on the main optical elements of a large telescope. We report here the performance of the films, the challenges to coat a 50 m2 primary mirror (M1) and our plans for coating maintenance.

Original languageEnglish
Pages (from-to)275-280
Number of pages6
JournalThin Solid Films
Issue number1-2
StatePublished - 28 Apr 2006
Externally publishedYes
EventSelected Papers from the 5th International Conference on Caotings on Glass (ICCG5) -
Duration: 4 Jul 20048 Jul 2004


  • Durability
  • High reflectance
  • Low emittance
  • Mirror
  • Silver
  • Sputtering


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