Thanks for the answer.
Well, a CO2 laser can engrave the copper directly (I think). But It's
so much more expensive than a DVD-RW laser.
How does a CO2 laser tube cost? I saw How it works and it' so impresive.
--- In
Homebrew_PCBs@yahoogroups.com, Mark Robinson
<mark.robinson@...> wrote:
>
> A laser from a DVD burner should be quite adequate to expose
photoresist.
>
> I played around with large argon lasers and scanners as a means of
resist
> exposure rather a long time ago.
>
> It was difficult to keep things square, the right size and in focus
but the
> results were still rather acceptable.
>
> A x-y plotter rig like those used with CO2 laser engravers would be
a much
> better option and a great deal cheaper.
>
> You'd probably want to use a considerably longer focal length lense.
>
> X-Y CO2 laser engravers usually have the collimated laser statically
mounted
> and shining along one axis hitting a travelling 45 degree mirror which
> redirects the beam up the other axis to another travelling 45 degree
mirror
> which in turn directs the beam down onto the work through a focusing
optic.
>
>
> DVD laser diodes are probably best mounted on the gantry aimed
directly at the
> work.
>