Translator Disclaimer
6 July 2018 A UV-enhanced protected silver coating for the Gemini telescopes
Author Affiliations +
A 4-layer protected silver coating was chosen for the Gemini telescopes due to its high reflectivity in visible and infrared wavelengths. Due to the reflective and absorptive properties of silver, the Gemini 4-layer coating suffers from poor reflectivity in wavelengths shorter than 400 nm. By utilizing different dielectric materials for protective layers it is possible to enhance the reflectance of silver to 350 nm, without compromising infrared performance or coating durability. Several different recipes were found that achieve a goal reflectivity of 80% at 350 nm and 90% at 400 nm. Five recipes were chosen for testing based on their modeled UV enhancement, the protective properties of their materials, and their simplicity. These recipes consist of variations of aluminum oxide, as well as silicon dioxide or silicon nitride. The aluminum oxide replaces the nickel chromium interlayer in the current Gemini coating and provides a receptive surface for the other protective layers. These materials were chosen because they can be produced in the Gemini coating facility without requiring significant and costly upgrades of the sputtering cathodes.
© (2018) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
T. Schneider and P. Stupik "A UV-enhanced protected silver coating for the Gemini telescopes", Proc. SPIE 10700, Ground-based and Airborne Telescopes VII, 1070048 (6 July 2018);


LSST coating plant status and progress
Proceedings of SPIE (July 05 2018)
Coating the 8-m Gemini telescopes with protected silver
Proceedings of SPIE (September 23 2004)
LSST reflective coating studies
Proceedings of SPIE (July 05 2006)
Low reflectivity materials for the vacuum UV Mg and...
Proceedings of SPIE (October 14 1997)

Back to Top