--- In
Homebrew_PCBs@yahoogroups.com, Philip Pemberton <ygroups@...> wrote:
>
> The trick will be in figuring out how small the spot actually is, and if
> it's accurately focussed. There is no way I'm focussing it with a
> photographic focus-finder, even on low power with a set of laser safety
> goggles...!
>
What I do is run the laser on a pulse generator with about a 1:1000 duty cycle. That gives a bright enough spot for focusing without too much light.
> BTW, this is all for another pet project of mine -- a laser photo
> printer. Basically printing straight onto photographic paper using the
> scanner assembly from a laser printer. Once you expose the paper with
> the laser, you develop it as normal in the usual B&W chemistry (I've
> been using Ilford paper developer and Rapid Fixer).
>
Yes, I can swap a plug-in board on my photoplotter to do grey scale.
It takes two consecutive bytes for a 12-bit DAC, so resolution drops to 500 DPI, then I repeat every raster line, to get 500 x 500 DPI.
I use Kodak digital sciences laser recording film, apparently made for laser recording of medical scans. I don't know if regular B&W paper is red sensitive.
Jon