Garage Door Sensor?

You know those sensors next to the garage door, that if tripped, the garage will stop closing?
It's so that if people (mostly kids) walk or run through, it won't close on them.

There's a little rectangle plastic box on each side of the garage, and each one has a lens pointing to the other.

I would bet they're using IR lasers.

Question is, what's the strength?

probably <5mW

Definitely <5mW, I couldn't imagine falling over and getting blinded by a garage door sensor.

I have actually built an alarm trigger (I think similar thing..) using simple parts that included LDR (light dependent resistor) and simple IR LED (like one of those you find inside your TV remote).. I just put the IR LED inside few centimeters of black tubing so it would send a more concentrated beam and that was it   No lasers   If I remember right it only worked max 3 meters and was affected by sunlight if the receiver was badly adjusted.