Homebrew PCBs

> Phil P wrote:
> Is there any chance of you posting some more
> info about the optics block?
> I've been playing around with an RGB laser set
> (red diode, green DPSS, BluRay/HD-DVD playback
> diode) and I'm curious how you got the spot
> size down. The best I've managed is about 0.5mm,
> which is nowhere near small enough to get any
> reasonable amount of resolution (about 50DPI
> by my reckoning)...

If you have a bad shaped laser to start with
(Most Laser Diodes do) then you will need a
couple of lenses to get to a small spot.

Either one lens to do something about the
astigmatism and one to shrink it OR one lens to
spread, go through an aperture (pinhole) and
another lens to get the small spot

Blue Sky Research have some laser diodes with
a micro lens built on the front.

http://www.blueskyresearch.com/c/b/posts/view/38

You will note they do down to 0.025mm spot size
(perfect for 1000dpi)

The other place to look at it

http://www.optima-optics.com/ld_kit.htm


When you build your laser plotter, you actually
want you spot size LARGER than the DPI you are
aiming for.

Also the elliptical beam is not so much a
problem either.  You just align it so the short
axis is with the drum.

I got as far as electronics, print driver and
a crude drum before I put my project on hold
a while back.  All this talk has got me back
in the mood :D