Re: [ATM] ritchey cretians

[Jim Burrows <burrjaw@earthlink.net>]

At 2008-01-17 17:16 -0500, Mikhail wrote:

>I am a bit new to the group, and am wondering if anyone has good sites, or
>has even done a Ritchey Cretian? I am very interested in this project
>because of how challenging it can actually be.

Mikhail,

You're right, Ritchey-Chrétien systems are REALLY 
challenging, construction as well as spelling 
<g>.  There was a guy on this list working on a 
24" RC, but he died before he finished it - hope 
that doesn't happen to me <another g>.  A place 
to start is Texereau, p. 147, Eq. (42, 43), 
giving the conic constants for the two RC surfaces.

I've generated two .zip files:
         http://home.earthlink.net/~burrjaw/public/aplanat.zip 
(2001-08-27, Win32, 15.7 k)
which goes into the design of RC systems, and
         http://home.earthlink.net/~burrjaw/public/rc_atm.zip 
(2007-08-27, Win32, 85.3 k)
that has a test for RC surfaces.

You can use good ol' Foucault on the primary, but 
the secondary is hard to do.  The usual method is 
to make a concave mirror to the proper specs and 
use that for a contact fringe test of the convex 
secondary.  I think it's kind of hard to get ~ 10 
nm accuracy that way, and you can't try to fudge 
the parameters to get a best fit to the 
"finished" primary.  I use a non-null Hindle test 
(I should say "using" - I've been fiddling with this for a LONG time).

         -- Jim Burrows
         -- http://home.earthlink.net/~burrjaw
         -- mailto:burrjaw@earthlink.net
         -- Seattle N47.4723 W122.3662 (WGS84)

_______________________________________________
ATM mailing list http://www.atmlist.net/