Newton's Rings

[wier@xxxxxxxxxxxxxxx (Bob Wier)]

| RBT 4G Nimslo format   21 x 16mm with Anti-Newton glass

This kind of reminded me of a question I was going to throw out
to you optical gurus on the list.

Awhile ago I had the opportunity to try to scan a glass plate stereo
view using a 300*300 dpi flatbed scanner (agfa arcus). This is the setup
where you have a transparency adapter light in the cover of the scanner,
which
shines thru the media to the receptor electronics.

I discovered I had a periodic darkening in the scanned image, which
repeated down at about a 50 dot interval. The interesting thing is that
it's not rings, but a straight line, oriented with the axis
of the illumination tube in the transparency adapter.

Question: was this a newton "ring" or something else? If you have, say
an 8*10" glass plate negative, would there be a large enough piece of
anti-newton glass which could be placed between the glass of the photo
and the glass of the scanner deck? Or would that do any good?

If there is any interest, I can place a piece of this image out on
the ftp site for people to look at - unfortunately I wasn't able
to scan the entire stereo view during the time I had access to it
(museums/libraries are kind of touchy about letting that sort of thing loose,
particularly back at my *old* school (Northern Arizona University), where
they were stunningly non cooperative in using computer technology for image
processing of historic photos).

THANKS

    ====== wier@xxxxxxxxxxxxxxx ======
   keeper of the Photo-3d, Motorola
 MC68HC11, Overland-Trails, LDS State
Research Outline Guides and other stuff
     (currently in Ouray, Colorado)



------------------------------