> If photoresist boards can be "influenced" by these high powered lasers then it could be a cheapish way of "printing" directly onto PCBs.
>
> Thoughts are to either have a rotary indexed table or maybe reverse engineer a cheap laser printer and pass the board through using the printer optics to raster print the image onto the board.
>
> Anyone know what happens to photoresist under a moderate power laser beam ?
>

The laser from a DVD burner most likely won't have any effect on the
resist. It's wavelength is about 650 nm, whereas the resist is
sensitive to UV. You may have luck if you were to use the laser from a
Blu-Ray burner, but that will set you back many hundreds of dollars.

The guts from a laser printer won't cut it either, because they use a
much lower power laser, and it's 780 nm, which is even further from
the seisitivity of the PCB resist. In addition, the spot from the
laser printer moves very fast across the surface, so will never stay
in one place long enough to affect the resist, unless you were to
write the same scan line many thousands of times before stepping on.
It might be possible to istall the laser from a Blu-ray burner into a
laser printer.. but then all the optics would be wrong and the beam
would need to be refocussed and realigned somehow.

I think a more promising route is to use a much higher powered laser,
and find a positive acting resist that hardens with heat, or use a
resist that the laser selectively ablates. I'm building such a system
at the moment, using a CO2 laser, but it won't be functional for a few
more months.
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