Re: ATM Active mirror figure correction?

[Scott Rychnovsky <srychnov@chem.ps.uci.edu>]

>I am by no means an authority, but on an intuitive level, it seems to me
>that there would be an upper limit to the mirror size that would lend
>itself well to a single tensioning bolt in the center for parabolizing.
>For instance, a very large, thin mirror might deform in a manner that looks
>more like a cone than a parabola.  It would be interesting to see a program
>such as PLOP for simulating tensioning bolt arrays affixed to the backs of
>thin mirrors.

Mike,

Richard Schwartz has posted on this topic in the past.  The problem is that
the distortions from a central bolt is maximum near the center.  Trying to
pull a sphere into a parabola requires most of the distortion to be located
near the outer edge of the mirror.  Using a center bolt to pull a sphere
towards a parabola just gives one a lousy parabola.  One can use more
elaborate cells to distort a sphere into a better approximation of a
parabola, but at some point this approach becomes too elaborate.  Don't
give up on figuring parabolas just yet.

Scott
--
Scott Rychnovsky
srychnov@chem.ps.uci.edu