Unstable Brightness?

I recently bought a "5mW" green laser that is pretty overspec. The only problem is, it takes a while to warm up (I thought it was broken at first). However, even when it is warmed up, it'll be very bright (30mW) for maybe half a second then drop down to probably 15mW. The violet laser i bought from the same place is more constant.

Is there a reason for this inconsistency in power? Is it something I can fix?

Green Lasers are notorious for unstable outputs...
The cheaper the Laser the cheaper and less quality
the crystals....
As the crystals warm up they change characteristics
and therefor output...

Jerry

Sorry, as Jerry said there is probably nothing You can do except try a new battery.

There is likely a good reason why laser modules vary so much in price.
(Roithner Lasertechnik charge $118 for a 30mW green module.)