Re: ATM 12" F2 mystery mirror

["David Harbour" <scarab@peakonline.com>]

Bill-

I have a suspicion that this mirror might have been intended as a
collimating source for optical testing. Not as popular as it was, compared
to autocollimating, but a well figured short focus paraboloid used with a
very small, intense light source exactly on the optical axis exactly at
focus makes a wonderful collimator for testing lenses or other mirrors. Just
a guess- yoiu may have to live with this mirror as a "mystery". Many mirror
have passed through my hands that had mysterioius features, and it's kind of
fun to try to figure out why a mirror has a particular feature or two. (Are
there any eyepieces that will work well with an f/2 cone of light? If not, a
Barlow would give you an f/4 with the cokmpactness of an f/2 (that is, if a
Barlkow will work okay with an f/2 mirror)
Good luck with the optic-

Dave


----- Original Message -----
From: William Kelley
To: atm@shore.net
Sent: Saturday, August 04, 2001 12:24 AM
Subject: ATM 12" F2 mystery mirror


I have acquired (as a gift) a 12- 3/16",  F2 , mirror apparently of Pyrex
and 1 -1/3" thick. Figure not tested, but a first superficial look suggests
is is very hyperbolic. Story is that the, now deceased, owner bought it many
years ago from Bausch & Lomb and intended (from some crude sketches he made)
to make a Dobsonian of it in the style of the early Coulters'. Ronchi lines
very smooth and sharp so it was made for some fine optical application. I
will, of course, determine the figure- but with this much- does anyone have
any idea what it might have been used for?

Regards to all-  Bill