Thread: Mirrors
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Old 14-03-2014, 10:29 PM
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pdalek (Patrick)
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Join Date: Mar 2013
Location: Melbourne, Australia
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The first telescope mirrors were metal. Soon switched to glass - much easier to make.
The old Amateur Telescope Making series of books described making metal mirrors.
Lots of military mirrors are beryllium - nasty poisonous stuff - not for home use. Beryllium is used for the James Webb Space Telescope mirrors.
Other metals have been used in military or space applications where performance outweighs cost.
I think the mirrors for the MAGIC Cherenkov telescopes are aluminium.

Metal is generally difficult to polish well - random crystals polish at different rates, also work hardens in patches. High thermal expansion is a problem.

Several liquid metal - mercury - have been made, I think one is still operating in Canada.

Some new designs using carbon composite, e.g.
http://www.compositemirrors.com/
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