15 October 2012 Coating the 2-m level primary mirror with protected aluminum
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Proceedings Volume 8415, 6th International Symposium on Advanced Optical Manufacturing and Testing Technologies: Large Mirrors and Telescopes; 841517 (2012) https://doi.org/10.1117/12.966816
Event: 6th International Symposium on Advanced Optical Manufacturing and Testing Technologies (AOMATT 2012), 2012, Xiamen, China
Abstract
In order to evaporate the Ø 2.4m large-scale speculum, we have developed a high-vacuum resistance evaporation machine which is of the nation’s largest bell-type, and we first propose to use the structure of the protected-Al coating with SiO coating by evaporating from top to bottom. The results show that the non-uniformity of aluminum coating is no more than 5.17% within 1.8 meters in diameter, also after environmental testing, there is no change on the mirror surface, and the reflectance decreased less than 1%. The average of the speculum reflectivity is Rav<88%@350nm-1800nm and Rav<90%@ 400nm-2500nm.We have separately completed the Ø 1.8m plane mirror in April 2011 and the Ø 1.8m concave mirror in October 2011. The results show that the PV value is less than λ/10 after evaporation and the RMS value has no change.
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Wenjun Pei, Hongxiang Liu, Weichuan Du, "Coating the 2-m level primary mirror with protected aluminum", Proc. SPIE 8415, 6th International Symposium on Advanced Optical Manufacturing and Testing Technologies: Large Mirrors and Telescopes, 841517 (15 October 2012); doi: 10.1117/12.966816; https://doi.org/10.1117/12.966816
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