Its worth starting out talking about this project with the problem. I have a lab and I have lasers but I have no power meter.

Some of my lasers are diode lasers and because they are diode lasers they more or less output laser power that is directly proportional to the current into them. Some of my diode lasers are *capable* of outputting 30-50 mW of optical power.

This makes them Class 3B lasers. Class 3B and Class 4 lasers require more safety precautions to keep your eyes safe than Class 1, 2, and 3R. If I limit the optical power of the lasers to < 5 mW in the visible then they become Class 3R lasers, and my eyes are a lot safer.

Because I don't really need heaps of power out of my lasers this is what I want to do: limit the current to limit the power. Problem is I need to measure the power to limit the current. I need a laser power meter.

I looked into buying a meter, from the normal big 3 optical suppliers in the United States solutions cost 300-2000 dollars.

I believe with calibration a more affordable open hardware solution can be constructed.