In research for our electronics-embedded art-book project, I wanted to be able to generate a range of possible colors. Combining red, green, and blue light, and varying the intensity of each channel (using the PWM ports of an Arduino board) seemed like a good idea.

I started using the single unit (5mm diameter) RGB led from Sparkfun. link (BTW: This is a great site with lots of resources.) Their LED is really bright, but the separate red, green, and blue nodes can't really be expected to lie dead-on at the optical center of the plastic lens in the component. So their beams do not overlap very well. That didn't bother me because I only wanted a soft diffused output anyway.

So... Here are some tests using various material. The first thing I compared was using a thin gob of cotton, vs. actually scratching-up the lens of one of the LEDs.

Diffusion test 1

This is what the resulting patttern looks like on thru a 1/8" piece of white plexi.

Cotton vs scratching

This shot isn't color corrected, but does show how the cotton diffuses better at the expense of attenuating the output. The pattern from the scratched LED is actually interesting, but doesnt mix the color too well.

To be continued....