Re: [ATM] Borofloat 33

["Bob May" <bobmay@nethere.com>]

You really can't test float glasses with a Ronchi test without
first having the glass surfaces polished flat.  It doesn't take
much for the glass to deflect the beam enough to see strangeness
in the passage of light through the glass.   Having a gentle
figure of revolution (sphere)  will produce the  curved lines
that parabolic mirrors produce and you can fight around that by
rotating the glass to see what rotates and what doesn't in the
image.
Bob May
bobmay at nethere.com
http: slash /nav.to slash bobmay
http: slash /bobmay dot astronomy.net
Replace the obvious words with the proper character.

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