[ATM] Need advice on my ronchigram

["Scott Krallman" <skrallman@hotmail.com>]

Hi all,
I'm working on my first mirror.  It is an 8" and the focal length is about 
6.6.
I've been polishing for about 8 hours, and hopefully I’m on the way to a 
spherical surface.
When I laser test the surface it looks pretty good in the center, but it 
looks like I've got about a 3/8" strip around the edge that still needs more 
polishing.
I’ve read that I'm not suppose to test the mirror until the surface is 
completely polished because the results are misleading.....but I did it 
anyway... couldn’t resist.    This is what I've got:
http://www.atmlist.net/contrib/skrallman-at-hotmail-dot-com/image0002.jpg

This was taken inside the radius of curvature with a  100 lpi screen.
I was stunned because I was expecting straight lines, or at least something 
close to it.
Do I have a problem, or is this because I’m not polished completely?     If 
I need to go back to grinding (heaven forbid) I’d like to do it before I put 
in another 4 hrs of polishing.

Thanks for your help.
Scott Krallman

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