Bogdan wrote:
> It is 1.5mm in thickness. Was this a standard thickness for
> glass plate?
Yes, 1.4 - 1.6 mm is (was) the accepted norm.
> Is there someone in N. America that still makes glass plates, for
> scientific purposes? I read somewhere that astronomers still use glass
> plates for making time exposures over several nights. Where do they get
> their plates?
Last I knew, Kodak still supplied coated glass plates -- but I heard a
rumor that they no longer produce them and are selling off remaining stock.
Don't know if it's true.
The plates were generally crown glass, or more recently borosilicate
"crown" (BK7), graded for flatness and inclusions and polished. I bought
up a pile of surplus Kodak glass in the '80s, but haven't seen any since.
Any large glass supplier should be able to cut appropriate blanks for you,
although it may not be cheap if you want guaranteed optical quality.
Best regards,
etienne
Received on 06/22/06-07:18:52 PM Z
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