To: "Scott Berfield" 
Cc: atm{at}shore.net, owner-atm{at}shore.net
From: Hugues.Laroche{at}ses-astra.com
Reply-To: Hugues.Laroche{at}ses-astra.com



 Can you folks take a look at  the following links
 and give me some pointers on how to correct the sharp  transition
 I am seeing? Am I totally screwed? I have been working tool on
top  with a W stroke of app. 1/3 total displacement. Mirror is 12.375"
diameter, FL  is app. 56", and the
 ronchi grating is 150 lpi.

Hello Scott,

> I  finally took a look and appear to have messed up.

then

>I have included a knife-edge  image in case it helps.

I wouldnt say that. Just it is true that this figure is a weird one and I
wonder how you could land on it? Was the lap/mirror contact good? The
figure seems rather smooth which confirms this...

Now the good news it that is could be worse. The extreme edge is not too
bad (at least, I have myself made worse edges at end of polishing). The
center looks very spherical.

I never had your situation, but what about pressing your lap as a star lap
(don't scrape your pitch, just press with a cut-out plastic sheet),
continue
as you did (not too much overhang) and test soon? This could blend
progressively the zone.

I am interested in what the gurus :-) would suggest...

Happy ATMing!

Hugues




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