Whats the duct tape for??? lol

I know the laser motion detectors for alarms you can pick up at HD, when something breaks the laser beam it sends a voltage (or something) along one wire that you have access too, inorder to tie into your alarm system. I was thinking maybe there is a way to use that output and do something useful with it.

It'd be nice for when you were practicing alone and wanted to keep track of your laps and times as you practice.