Re: Too hot? Too cold?
Too hot can have bad effects on everything. First off is the diode you can kill. High temp can also screw with just about everything else from the crystals to the driver.
You laser may cease to work at all in low temp, but its unlikely to cause permanent damage (IE, bring it back to room temp and it works fine). Only problem I see with very low temps are:
1. condensation getting inside the laser/optics if the laser is itself cold, but in a warmer enviroment
2. thermal expansion if you move it from cold to warmer temperatures quickly, which could cause problems as major as cracking an optic, or cause more subtle damage to the internals.