I know a bit about animal behaviour and would strongly advise against your proposed idea. Most wild animals, bears included, prefer not to come into contact with humans unless there is a need. The need (in this case) with bears would propably be either hunger or you are somewhere he/she wants to go.
In either situation you become competition (or the food) and bears usually win unless these types of competition unless (a) you frighten them away or (b) you escape.
Very loud noises usually work, ie. gunfire etc. However, pain usually acts as a positive stimulus and bears which are used to fighting and hurting each other are then almost impossible to stop by a man unless killed.
You would stand only a 50/50 chance of blinding a charging bear in one eye with a laser (remember he's got two) and he's also got an acute sense of smell. OBTW charging bears cover ground quicker than you can run despite there size!
I would honestly rate your chances of succeeding with this idea as zero and bear attacks are usually fatal if you are unable to effect an escape.
In this situation it is better to have a Gun than a Laser!
Doug