In a message dated 9/19/99 5:42:55 PM Pacific Daylight Time, norcutt@xxxxxxx
writes:
<< I don't think the scanner could handle a
virtual image floating in the air. Of course, if we're gonna just cut
the wires we can also just grind the glass cause this 49 dollar scanner
is already a gonner anyhow. Even with the ground glass Warren may have
a valid point. There may be reflections coming off the bottom of the
case which need to be suppressed by painting the interior black or,
since it's a gonner anyhow maybe we can just remove the bottom. >>
Clearly unless you added some refractive optics you must use ground glass.
This is the same as a view camera so maybe you could get a spare for a large
view camera.(costly?) For experimenting (moderate quality) a piece of etched
Mylar as used for old engineering ink drawings would probably work. I bought
a small sheet of ground glass when I was in High school for a homebrew
optical system so it must be cheap. To get it really bright may require
special etching/grinding : this is the same issue as with viewfinder screens
for SLR's. The "Etch" makes a big difference to brightness and resolution.
(a trade off) Alternately rear projection screens removed from a an old
fashioned salesmans portable movie projector might be ideal. I think the
issue of lack of contrast in the internal reflections of the box may have
been partiallty addressed in the scanner design in the sense that the
scanning head screens the portion of the image and an inch or two on either
side from stray light reflected from the base. I believe (but have never
checked ) the scanners use reflective rather than refractive optics to focus
the line image down to the small CCD sensor arrary.
Tim Hughes
Hi100@xxxxxxx
< This message was delivered via the Olympus Mailing List >
< For questions, mailto:owner-olympus@xxxxxxxxxxxxxxx >
< Web Page: http://Zuiko.sls.bc.ca/swright/olympuslist.html >
|