Using red-sensitive film with a plotter

Very interesting! Why not regular film and a white LED?

...Jim Thompson

Hmm...

Do you mean photographic negative film (like for a large-format camera) or something else?

I never though of using ordinary photo film like that - I have some around somewhere (in the loft I think) - wonder if it's UV opaque when exposed (and not when not!) I must dig it out and find out.

Of course, what I really want is a focussed UV laser to draw straight on to the sensitised board.

Rick.

There was an almost identical photoplotting scheme sold as a proprietry product in the UK, about 15 years ago.

It was based around the Roland DXY1100/1200 plotter (which was an A3 flatbed with electrostatic paper grip). The high power UV source (about 500W) was in a separate fan-cooled box. A 1/4" glass fibre-optic bundle connected the two, plugging into the pen-holder of the plotter. I do not know what the optics were on the pen-end, but pen ran in contact with the film, with the normal pen-lift of the plotter apparently enough to reduce the UV to obtain a good light/dark contrast.

The UV film was quite sensitive (compared with other UV films), and it did require handling in semi dark-room conditions to avoid fogging. I suppose this sensitivity was needed to get good exposure at reasonable pen speeds and to avoid having to overplot.

Line film would be better because it is less sensitive and has a high gamma?, so develops to black or clear, with no intermediate grey scale. It is often green-sensitive, which conveniently allows working in the darkroom with an ordinary red safelight.

Hey, I never thought of a fibre optic guide for the UV - must be special glass to transmit it though (crown?)

I had a DPX2000 plotter (A2 flatbed) a little while ago, but sold it on eBay because I didn't have room for it. I really regret it now!!!