For 5 mW lasers or lower you might want to look into an optical sensor over the TEC type LPMs, as they are much more accurate for these power levels.
Thanks for the tip! I hadn't thought of this. I'll probably need to prioritize one of the TEC type at first since I have more of the "high power" units than the low-powered lasers such as this. It would be nice to see how much this little 589 nm actually outputs.