From: Mel Bartels 
cc: atm{at}shore.net
Reply-To: Mel Bartels 


> how importand ist it, that a mirror blank is free of internal stress? How
> much stress is can be tolerated?
> (may be Schott Duran). A polarizer stress test shows following picture:
> http://www.astrotreff.de/upload/Stathis%20Kafalis/20030605/sresstest12zolldur
> an.jpg
> As you see, there is severe stress visible. Though, I can't see any defects

I would not work such a blank myself.  The chances are good that figuring
will be difficult.

Mel Bartels

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