[dudeman2009]

As for where to buy one, I cannot help you there. However, a laser range finder may very well work. It depends on other objects using lasers of a similar type. For the accuracy of the finder, it could be very accurate, seeing the field, pointing the laser at the plastic backboard of the hoop would provide a nice reflective surface for the laser to bounce off. So would any semi reflective surface, they are quite reliable and don’t require a lot of understanding to figure out. The only thing to watch out for would be other robots in the way when it goes to refresh the distance.

(I do not know very much about interference between lasers of different K values but 2 identical lasers could cause interference in theory, I haven’t had time to try it out)

As for what others have said, Always be careful around lasers, even a little penlaser is capable blind you at 50ft