Re: [ATM] Flexed mirrors

["Bob May" <rmay@nethere.com>]

One of the nice things about flexing glass is that you can do it
to an unfigured but polished mirror, test it by the foucault test
(understinading that the sign of travel of the KE stage needs to
be reversed) and polsih out the sphere again.  When relaxed, the
mirror goes to the paraboloid shape. It should then test to be
accurately to whatever you tested before figuring under the
stressed condition and, being polished to a sphere, should be an
excellent figure.
You could also do it to something other than parabolic and then
flex to the correct shape in the telescope, reducing the possible
errors from a bad mirror cell as the forces won't be as strong as
wiht a spherical mirror being bbent all the way to a paraboloid
shape.
Bob May
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