Yeah, you can click my karma button if you want to test the function .... 
Ohhhhhhhh I didn't notice that lol. Yep, tested it out on both of you!
If you need something like those laser beam systems in banks which will turn on alarm when laser beam is crossed i have solution for you. You need a laser beam(you can get simple pointer laser) and you need photo diode(they are pretty cheap 10pcs on amazon is 7 dollars). You make simple little setup: first you tape sides of diode (you roll around it with isolation tape(black) so only cathode and anode are visible from the top) and you put laser beam strait to center of diode. Diode will let trough some amount of current (depends on laser strength of laser) so you will be able to hook up 5v to one side of diode and other side to arduino on analog in pins. Hope i helped.