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


Choose the concave side and start grinding.  The Pyrex blanks from all of
the suppliers are a lot less flat than that and make excellent mirrors. I
do prefer to see a smooth surface than a lumpy one as this makes the
mounting on points in the mirror cell move the optical axis around a lot
less..  Thus, if you hae a lumpy back then just spend a few moments
grinding against a concrete sidewalk or other fairly flat surface.  Getting
the curvature out isn't the goal but rather making the backside of the
mirror a smooth surface, thus you want to turn the blank about as you do
the grinding of the back surface.
Bob May
http://nav.to/bobmay
bobmay{at}nethere.com
NEW! http://bobmay.astronomy.net

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