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Proceedings Paper

Study of inverted thermal evaporation for large mirror
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Paper Abstract

From October 2010 to December 2012, the systematic study of the protected aluminum coating which is thermally evaporated downwards for large primary mirror had been developed. By adjusting the structure, it makes the physical nonuniformity of the bare aluminum films in the diameter of 1.8m drop to 4.18%, and the average reflectivity meets 95.09% in the band 400nm-2500nm. The optimized parameters suggest that the SiOx (1<x<2) protective film with the oxygen flow of 50sccm has excellent environmental stability, and the average reflectivity of the protected aluminum coating reduces just less than 5%. Further, the SiOxNy protective film which is formed with 25sccm nitrogen flow not only has the environmental adaptability as the SiOx film but also resists to the salt spray corrosion. But the average reflectivity of the SiOxNy protected aluminum coating decreases about 2%, reach 88.6%, in the band 400nm-2500nm.

Paper Details

Date Published: 2 September 2014
PDF: 6 pages
Proc. SPIE 9280, 7th International Symposium on Advanced Optical Manufacturing and Testing Technologies: Large Mirrors and Telescopes, 92800H (2 September 2014); doi: 10.1117/12.2068419
Show Author Affiliations
Wenjun Pei, Institute of Optics and Electronics (China)
Hongxiang Liu, Institute of Optics and Electronics (China)


Published in SPIE Proceedings Vol. 9280:
7th International Symposium on Advanced Optical Manufacturing and Testing Technologies: Large Mirrors and Telescopes
Wenhan Jiang; Myung K. Cho; Fan Wu, Editor(s)

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