RE: ATM Epoxy spin-cast mirrors: comments for experimenters

[Andy Saulietis <iss@pvtnetworks.net>]

Clark Andersen writes:

>I figure that if I can achieve an optically flat surface with epoxy (without
>spinning), then spin-casting would be a simle follow-on project.  I tried
>one experiment to achieve an optical flat.

IMHO spin casting to make an *accurate* paraboloid
by spin cating would be anything but *simple*. Refer
to the literature on how spinning mercury mirrors
are made - it works but the anti vibration and 
stability problems are formidable, not to mention
viscosity effects. The 3m NASA Hg mirror (currently
located here near Cloudcroft NM) had a spin cast
epoxy surface, but this was made to minimize the
quantity of mercury required and to reduce large
amplitude 'slosh' modes. The spin bearings are typically 
air bearings with servo controlled motors.

UV cured epoxy mught be a way to quickly solidify
a mirror if the spin problem can be solved, perhaps
with real-time figure testing to know when to 'freeze'
the epoxy.



   
Andy Saulietis
ISS Enterprises
39 Silver Fox Trail
Mayhill NM 88339
505-687-3067 voice
505-687-3021 fax, call voice or e-mail to set up
e-mail: iss@pvtnetworks.net