It's the most stupid of things to do, to target the occupants of a police vehicle which provides it's own evidence, easily upheld in court. The laser beam itself leads straight to the hand of the perpetrator and the helicopter can immediately record the evidence on video, identify the address or vehicle, or even the guilty individual and lead police ground vehicles directly to that location. Chances are, if the helicopter is there, the ground vehicles are not far away and in radio contact.