Instructables

Laser Tripwire Turned Off By Laser Pointer?

I was playing through my older Splinter Cell games the other day, and had my airsoft pistol next to me. I had attached a laser pointer on it, mostly for kicks and giggles. While playing Splinter Cell, I turned off a security camera by shooting it with some sort of laser from my FiveseveN and it gave me an idea. I decided that I'd like to make a simpler version of this for a scenario airsoft game. So my question for you guys is, is it possible to make a laser tripwire that can be turned off by aiming a laser pointer at some sort of sensor on it? If so, how much would materials cost me, and how difficult would it be to assemble? Could it be pulled off by someone with little electronic experience like myself? Thanks in advance!

Turning off a laser tripwire with laser pointer is a very feasible project. You would just need to add another sensor to act as the disable switch that will turn of the alarm when hit with the laser.

I'd recommend starting with the Another Laser Tripwire Instructable.  Since it already uses an Arduino to detect the trip laser it's almost trivial to add another sensor.  You would need to add another photocell wired similarly to the one used to detect the laser tripwire and connect it to a different input pin. You could then add code to poll the new sensor to detect laser hits.  When the new sensor detects that a laser is shining on it. the program would disable the alarm (and maybe light an led to indicate "safe")  instead of sounding an alarm.

Of course this isn't the only way to go about solving the problem.  You could build a new system with a different microcontroller or build the whole system using basic logic gates.

If you need any help with the circuit/code or want to go a different route don't hesitate to ask.
is there a way to shine a laser on a piece of clothing intertwined with metal that would make an alarm go off when the laser struck the material?