ATM re: Interferometric Testing?

[wmcclain@salamander.com (Bill McClain)]

> From: Del Stanton <sdl20@pacificnet.net>
> Date: Sat, 7 Sep 1996 15:52:00 -0700
> Subject: Interferometric Testing? 
> 
> How difficult is it to build a rig to do interferometric testing of a mirror?
> The rig I have in mind would produce an "amplified" contour map of
> the mirror's surface with the vertical scale magnified, showing the 
> deviation of the mirror's surface from the best fit "reference paraboloid".
> 
> Is this completely out of  reach for a determined amateur?
> 
> While I have a basic understanding of physical optics I cannot visualize
> how to make a suitable set-up.  Could one you suggest the appropriate
> books or journal articles?

I got this a couple of years ago: _Interferometry and Telescopes_ by
Peter Ceravolo, 42 pages, $20. from:

    Ceravolo Optical Systems
    Box 1427 
    Ogdensburg NY 13669

        or

    Box 151, 702 Pattersons Crns Rd
    Oxford Mills
    Ontario Canada K06 1S0

    voice 613-258-4480
    fax   613-258-3082

He sells the optics and software to do what you describe, or you can try
to roll your own from his instructions. As others have said, testing a
parabolodial mirror with an interferometer requires producing a
spherical wave front, which means introducing the proper null lens
(which he also sells). Or, you can test a completed instrument with a
large flat. Either requirement make the technique a bit less appealing
to me, although I would certainly like to try it someday.

-Bill