You can do this with sound. A hybrid system even better. I built tech ~10 years ago to track quiet, sound emitting objects in real time to sub CM resolution

You can do this with sound. A hybrid system even better. I built tech ~10 years ago to track quiet, sound emitting objects in real time to sub CM resolution using microphone arrays. And in one demo I even had a laser pointer mounted on a 2 axis.... "swinging thingie" (sorry, I'm not a mech-E) which would constantly stay pointed on the loudest object in the room, as it moved. Fun stuff. Creepy even. Shame I never found a use or a buyer for the tech. :/ EDIT: I bet an improved hybrid one would use sound to get within the right 1-2cm, with a zoom camera mounted on the pan/tilt apparatus to get it even more accurate.