Nomothumu 0.9, Time sensor for sport use

timekeeper- I stumbled across this thread and am very interested in your project. Its just the sort of thing I have been trying to figure out how to put together. I need a simple timekeeper -- that is triggered ON by a beam break, and then triggered back off by breaking the same beam again. And accurate to xx.xxx seconds. I am new to the forum (and arduino) and would like some more information if youre willing to help me. Thanks