Path: utzoo!attcan!utgpu!watmath!att!dptg!rutgers!cs.utexas.edu!uunet!mcvax!ukc!stl!stc!root44!hrc63!paj
From: paj@hrc63.uucp (Mr P Johnson "Baddow")
Newsgroups: comp.graphics
Subject: Re: Color desktop scanners (a technical discussion begins)
Summary: No such thing as a white laser
Message-ID: <658@hrc63.uucp>
Date: 8 Aug 89 10:47:34 GMT
References: <1869@ucsd.EDU> <5368@ficc.uu.net>
Organization: GEC Hirst Research Centre, Wembley, England. (uk.co.gec-rl-hrc)
Lines: 24

In article <5368@ficc.uu.net>, cliff@ficc.uu.net (cliff click) writes:
...
> the intensity of the reflected light.  Use different colored lasers (or
> filters on a white-light laser??) for different colors.  You probably
...

There is no such thing as a white laser.  Lasers produce monochromatic light.
White light is a mixture of all frequencies.

You would need three lasers and a mechanism for selecting them.

The rest of the idea, a laser printer based scanner, is pretty neat.

Would a parallel beam of white light work OK? Could it be accurate enough?
What about refraction errors and fringing in the optics?  What about filtered
white light?  How big is the average laser printer laser?  What about
mounting a photo-receptor in place of the laser and generally illuminating
the document?

-- 
Paul Johnson,         | `The moving finger writes, And having writ, moves on,'
GEC-Marconi Research  |                    Omar Kyham when contemplating `vi'.
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