Electronic goalposts

A perpetual problem when playing casual soccer is knowing whether or not the ball went through the goalposts. In fact, I estimate that we spend about 10% of the match disputing whether the ball went through the goalposts. Of course some goals are clearcut, but when you have no goalie, and the ball comes in at an angle, how do you know? And then there are disputes about height...

So, with the advent of those projector pens that project a sensitive laser keyboard, surely they can make electronic goalposts. I mean, have a little device that projects a rectangular area that you can set to whatever size (like 2m wide and 1m high or whatever). When the ball passes through this field, it records a goal. It should also be one way to prevent accidental goal recordings when the ball is rolling out of the goal.

Now somebody make this damn thing and give it to us!