Laser Sensors

[LiquidOrb24]

I'm wondering if anyone would know how to build a simple circuit that has a laser attached to it pointing off into another circuit that has a laser sensor on it. What I want it to do is if the beam gets cut off somehow between the two circuits, an alarm goes off to tell the person that the beam has been cut off. Kind of like a laser security system.

Any info would be greatly appreciated. Thanks

 

[plot]

what you want is an Infra-Red system, similar to this one **broken link removed**

that's a kit you can buy and build, that's a united states company, but the manufactor of the kit is based in germany if i'm not mistaken, so it should be readily available on websites wherever you are located.