Re: ATM "frozen" liquid mirrors

[RDuvall@pixworks.com (Robert Duvall)]

At 3:30 PM 2/19/97, CHEN@uit.gsfc.nasa.gov wrote:
>   This is in reference to Tom Warm and Brian Reynolds' post on
>spincasting epoxy mirrors.  I have been working on this subject for
>a number of years, and it is great to find someone else doing the
>same 'non-traditional' mirror making.   Permit me my two bits worth
>of comments, if I may.
>
<SNIP>
>     Finally, thought to mention that you gentlemen are following
>in a venerable tradition.  Spincast epoxy mirrors were made back
>in the fifties and sixties by various groups at the U. of California,
>U.S. Army at Fort Belvoir, Birmingham University in the UK, and
>astronomers at Cal Tech.  The General Electric Co.'s astrospace
>division used spincasting to make mirrors ** 10 meters ** in
>diameter!

>     Spincasting is a facinating subject.  I'll be happy to go into
>more details if anyone is interested.
>

Please do! What kind of optical quality at visual wavelengths have been
produced? What polishes well? I've heard on big mirrors, there are defects
as large as 1mm in the spin-cast resin base and that the resins expand
while they cure by an average of 5%.

I've been saving that SciAm article for several years now hoping to try
this someday. I notice there's been some info on this in the ATM archives,

Robert Duvall

Software Engineer,
Amateur Astronomer (TN),
Guitarist/Songwriter,
and General Scientist (according to my son)
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