Here is what I am trying to accomplish:

In the middle of a room, I have a mechanism with a laser diode mounted on it that can be moved in all axis by a motorized pan/tilt head type device. This mechanism is to stay fixed in the middle of the room at all times.

Now say that I have a phone for example. I want to be able to walk around the entire room all whilst having the laser pointer constantly following and aiming at the phone with as much accuracy as possible. 

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Which hardware, if any, should I use in this circumstance to help accomplish this? I can mount anything needed on both the tracking device (laser) and device being tracked (phone).

This is my first time working on a tracking system of any type. I have attempted a fair amount of research on the topic, but I am still left in a haze. Mostly everything I find has to deal with a camera tracking/following a point, but I would like to avoid this method if possible.

If more info is needed, let me know.