You need lasers. We got lasers. Lots of lasers. Too many, in fact. You should buy these and hook 'em up to your Arduino.
These are great little 3V 5mW laser diodes that are suitable for all kinds of hobby projects: break beam tripwires, line-of-sight communications, or just freaking out the cat.
You'll receive 50, count 'em 50 little lasers, but Sparky the T. rex is not included in your package.