Color enlarger using laser - Additive method

arturo_rs · 2025-10-26T08:20:51-0400

It is possible to make a color enlarger using lasers. I think, in principle, that "should work".

Using 3 lasers:

Blue: ~450 nm
Green: ~530 nm
Red: ~640–660 nm

The exposure and density will be controlled by the time the lasers emit light. It is an additive process.

The light before reaching the color negative should hit a diffuser for make the light even. Also, the lens of the laser should make a wider cone.

One problem that I found is the speckle. So, to avoid the granularity is using 3 o more lasers from every color to reduce that effect.

What do you think?

arturo_rs · 2025-10-26T08:23:12-0400

This video explain less or more how should work this process:

Instead using filters, color lasers.

Chan Tran · 2025-10-26T08:36:49-0400

I don't think you need to make it laser. There are printers on RA-4 paper that use laser but that is because they need to expose the tiny dots in a scanning like process. For projection enlargement LED would be OK as they can produce monochromatic light too.

Carnie Bob · 2025-10-26T09:02:42-0400

arturo_rs said:
It is possible to make a color enlarger using lasers. I think, in principle, that "should work".

Using 3 lasers:

Blue: ~450 nm

Green: ~530 nm

Red: ~640–660 nm

The exposure and density will be controlled by the time the lasers emit light. It is an additive process.

The light before reaching the color negative should hit a diffuser for make the light even. Also, the lens of the laser should make a wider cone.

One problem that I found is the speckle. So, to avoid the granularity is using 3 o more lasers from every color to reduce that effect.

What do you think?

Lambda was developed in the mid 90's using RGB laser exposure, I owned one for years and did RA4 prints, Cibachrome prints and Fibre Base Silver prints on it, today there are still labs using this device.

Carnie Bob · 2025-10-26T09:03:57-0400

Also ancient history , in 1974 I was using a Nord Enlarger which used Additive light RGB to make cprints.

Chan Tran · 2025-10-26T09:35:35-0400

The Minolta/Beseler 45A color head which uses xenon strobe is also additive.

ic-racer · 2025-10-26T09:36:07-0400

Fire the lasers into a light pipe. (for diffusion)

Chan Tran · 2025-10-26T16:26:47-0400

With today's technolgy using additive method makes sense but there is no need to use laser.

koraks · 2025-10-26T17:03:05-0400

arturo_rs said:
The light before reaching the color negative should hit a diffuser for make the light even. Also, the lens of the laser should make a wider cone.

So you don't use lasers to begin with, as it just makes things unnecessarily complex, and exposures will be slow. Instead you use LEDs. Plenty of people have built LED light sources for enlargers by now. Mostly for variable contrast B&W, some for color. I've done the latter; I've built several versions and I've been using RGB LED exposure for both b&w and color printing for several years now.

DREW WILEY · 2025-10-26T17:20:52-0400

There are several manufacturers of photosensitive laser printers. Those are very expensive industrial machines coupled to dedicated scanners, automated paper cutters, and direct RA4 roller processor output.

LED is the new kid on the block and shows a lot of promise.

I built a couple of narrow-band true additive RGB pulsed halogen enlargers, up to 8x10 inch film size capacity, designed for up to 30X40 inch prints. Makes that old Phillips design posted earlier seem like a tiny toy by comparison. Mine is over 14 feet tall. Then I have a second version for up to 5x7 film. The quality of color is analogous to what big pro RGB laser printer deliver; but the detail is even better, since no intermediate scanning takes place.

Color enlarger using laser - Additive method

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