11 thoughts on “Big Mirror pr0n

  1. A friend of mine asked me what the biggest sputtering application was. This is the biggest that I know of- it's an 8.4 meter diameter mirror. I believe they use a radial arm magnetron head of about 4 meters length to sweep the mirror and coat it. Sputtering is easier to do than evaporation, as you'd need a vacuum chamber with more depth (or fifty million little pieces of aluminum on tungsten to fire) to do vacuum evaporation of a coating onto it. Although this video is touted as "Coating operation of an 8 meter telescope mirror at Paranal", in fact the only glimpse of the actual coating operation occurs for about 10 seconds at the 7:25 mark. The rest of it is getting the mirror out of the telescope, moving it to the coating building, cleaning off the old coating…you get the idea. Pretty cool nonetheless.

  2. That was amazing. How often do they have to recoat?

    I see by virtue of Google Maps terrain that the site is at about 8,900 feet AMSL in what looks like the Atacama Desert, where it has never rained in recorded history, whereas the Keck Observatory onthe Big Island is around 13,500 feet, where it rains and snows frequently. Given the complexity of doing all this beautiful industrial stuff in remote areas, why does the world need two such sites?

    And hey lookie: the Chinese are building one too: https://www.youtube.com/watch?v=7SRV3rnULO0

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