[ATM] refiguring a 20 inch Pyrex f/2 cassegrain

[Guy Brandenburg <gfbrandenburg@yahoo.com>]

Has anybody ever tried refiguring a 20 inch Pyrex f/2
(or thereabouts) Cassegrain? I understand that the
primary on the one I have in mind - it belongs to the
Hopewell Observatory, of which I am a member - is
supposed to be parabolic, and that it's not figured
very well. Supposedly it was optimized for infrared
wavelengths, but that doesn't make a lot of sense to
me, because reflective optics reflect all wavelengths
the same way.

I am considering refiguring it, but I've never worked
on anything either that large or that fast. (I am
working on a 16.5" parabolic f/5 pyrex primary, but
have not yet gotten to the polishing stage, much less
the figuring stage.)

Any comments from anybody who has actually done that
would be more than welcome.

Guy


Guy  Brandenburg
Washington, DC
My home page:
http://home.earthlink.net/~gfbranden/GFB_Home_Page.html
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