Re: [ATM] Pre-stressed figuring?

["matt" <electro_optic@bellsouth.net>]

-----Original Message-----
From: Mark Holm <mdholm@telerama.com>
To: eyesky <eyesky@gmail.com>
Cc: atm@atmlist.net <atm@atmlist.net>
Date: Wednesday, August 03, 2005 8:39 PM
Subject: Re: [ATM] Pre-stressed figuring?

>Also, the method that has been used many times for the production of
>Schmidt corrector plates is a stressed glass method.  Berhardt Schmidt
>invented the method as well as the optical design.  It is called the
>vacuum pan method.  (Do the commercial SCT outfits use the vacuum pan
>method?)
>
>--
>Mark Holm
>mdholm@telerama.com

there was a guy a few months ago selling a "Pyrex blank" on Astromart . The
thing turned out to be a Celestron vacuum pan tooling , had the 8 radial
grooves clearly visible , was about 20-22" diameter. Not sure if this was
current tooling or some old 20" Celestron stuff but it was once used by a
commercial SCT maker ...

best regards,
matt tudor


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