Hi all,

I'm working on a project which involves scanning line drawings into
memory (a large SRAM). Ideally the images will be laser printed on
white paper, so the contrast will be good and lines should be sharp.
But other users may not adhere to recommendations, for a variety
of reasons, so I'm looking for components or techniques that will
reasonably cover all eventualities

My aim is to be able to resolve to 0.5mm or better. I've made an
X-Y bed, 600mm x 600mm (but I may well go bigger), with a
couple of steppers and threaded rod that has good positional
resolution, now I need a read head

Some things I hope to try ASAP -

Illuminate from the back with an LED with a opto sensor above the
paper. This would involve an extra mechanism for the LED to follow
the read head. No big deal

A reflective or proximity opto, which would bounce IR off the paper

Some lens system to enlarge the detection area

I've used these techniques for other projects but not with resolution
as the primary goal. Mostly for event detection. I expect I may have
to restrict a sensor's field of view (eg pinhole mask)

Any other ideas or experiences ? I keep daydreaming about cameras
but I don't think that's necessary, and I want to use components that
are cheap and repeatedly available. Even something like an optical
mouse sensor perhaps. Cheap enough to scavenge from a bought one
or pick up as broken

TIA

Joe
--=20
http://www.piclist.com PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist
.