My RGB laser arrived yesterday, and today I got to play with it. There is no such thing as a true white laser because the nature of laser light is centered on a single wave length of light. However, using three lasers and beam combiners can produce a beam that visually appears white. This laser module has a 200 mW red, 100 mW green, and 200 mW blue laser diode with two beam combiners. The result is a 500 mW white beam.
My experiments with making a laser tunnel went well, but one item I failed to accomplish was a tunnel with counter rotating fingers. I tried using a PWM to dim the laser for some fingers, and keeping one at full brightness. But the laser can module can only transition no faster than 20,000 times/second which for this project isn't fast enough. However, having separate lasers to control, I can accomplish this effect. Rather than dimming a single laser, I can simply turn one or more of them off.
The changes to the code were minor. I simply duplicated the logic for the timer compare A interrupt and setup a second set of variables for timer compare B interrupt. This allows timer compare B to mimic what compare A does, but with different parameters. Didn't take long before I had the effect I was looking for.