Re: ATM "frozen" liquid mirrors

[ab866@freenet.durham.org (ric rokosz)]

Aart Olsen writes:
> 
> Why solid epoxy?  I'd try a molded concrete substrate covered with just a
> thin layer of spin cast epoxy.  That way you would benefit from the
> stiffness and low temperature coefficient of the concrete.  If you use a
> good mold for the concrete (e.g. that convex tool you have lying around)
> you could perhaps get by with a heavy varnish -- the stuff used to finish
> bartops -- because you'd need just a millimeter or so for polishing and
> figuring.  Painting the rest of the concrete surface with polyurethane will
> prevent it from outgassing when aluminizing.  It should be easy to cast
> ribs into the concrete to save weight, and it would be handy to embed some
> bolts for mounting too.
> 
> 
> Aart M. Olsen         mailto:aart@uiuc.edu          217-244-4688
> Library Systems Office      Univ of Illinois at Urbana-Champaign
> 
> 
> 
I've watched this thread for the past few days,and am really hoping that
you know that these very high expansion materials are only good for crude
infrared concentrators.Cement mixed with epoxy does not a optical mirror
make!

Ric
Toronto

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