From: "Bob May" 
To: "atmlist" 
Reply-To: "Bob May" 


Yes, both surfaces do need to be polished in order to get the Newton's
fringes to come out.  You don't need a really good polish (50% will already
show some fringing) for the first checks of the ROC on the target surface.
As to generating the test plate, you can just do the grinding with a glass
tool and that is the test plate when you get it polished up and have the
exact radius that you want - sorry, no tile tools here.  After you have the
tool done right, the convex surface can be polished up and the ROC made to
match that of the tool/testplate.  Remember that when you do parabolizing,
you are indeed changing the ROC of different parts of the mirror! Bob May
http://nav.to/bobmay
bobmay{at}nethere.com
NEW! http://bobmay.astronomy.net

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