Re: [ATM] ATM Foucault images

["Stephen Koehler" <s.c.koehler@gmail.com>]

David,

> So what does this surface look like?  How would one attack this? The usual
> go back and fine grind again aside, how would one remove this astigmatism?

In my analysis, I assumed pure primary astigmatism, which is a simple
saddle shape.  If you were to attack this, I think you would have to
somehow remove glass from two opposite sides of the mirror, while not
disturbing the other two sides (much).  The analysis does indicate the
angle of the astigmatism, although I didn't go as far as to get clear
in my mind which side is the high one.
I believe the usual approach is to go back to find grinding, while
keeping an eye on what conditions led to the astigmatism in the first
place, so they can be corrected.

I know that James Lerch has directly worked astigmatism in the past. 
I'm pretty sure he did it using a 2D surface map from interferometry,
however.  That gives you MUCH more information to work with.

--
Steve Koehler
_______________________________________________
ATM mailing list http://www.atmlist.net/