I just put that into a google search and found this-- there is much more there - go find it
Sam's Laser FAQ - Items of Interest
Laser Power, Photons, How Much Light?, Beam Profile
____________________________________________
About HeNe Laser Power Ratings
Any given laser - be it a HeNe, argon ion, CO2, or other CW laser; or a pulsed laser like an Nd:YAG, Ti:Sapphire, or excimer, will have two, maybe three, power or energy ratings:
The manufacturer's power rating based on model. This is the one you find in the catalog or spec sheet and will be the minimum output produced during the warrantied life of the laser under a given set of operating conditions.
For HeNe lasers, there is a single rating since these are generally operated at their nominal tube current all the time. Example (Spectra-Physics HeNe laser model 105-1 HeNe laser): 5 mW.
So that 10mW you saw there means LESS that 10-- could be 9 or .5 both are less- but at least when new that SP should output 5 mWs- most likely red, odd that that perticular model would be the one Sam uses for an example!!
They are quite rugged- I would say better than 50-50 chance that it works or could be made to work. what was the date on it?? (not that it matters that much)