There are some lasers for sale that you can use to light paper and other things on fire. I am guessing that they were aiming one of those at you. Since this was on a university campus, it does not surprise me that some kid would do that to you.

It is hard to tell where a laser is coming from without looking directly at it. Unless there is smoke or fog, even a visible light laser is invisible until it hits something. There is not much you can do in this situation. If you suspect they will do it again to you, then bring a video camera with you and slowly pan it around and hope that it catches where the laser is coming from. That might give a clue as to who might be shooting the laser.

Or you can buy a green laser yourself and aim it right back at the jackass that is shooting one at you. They won't expect it and will be looking directly at you.....