[EagleRob]

Well if they're going to do this then they also need the plane of the goal lines extended upward from the field as well so we can know if the ball breaks the plane. The first down laser could be made eye-safe if the divergence was large enough or if face shields filtered the 532 um green wavelength (guessing it would be green due to relatively cheap cost and small size of frequency-doubled Neodymium YAG lasers) but I can't see how it could be projected across the field with 28 sets of feet getting in the way.