Laser Power Settings Via PWM Can Fool You

When I bought my first cheap Chinese laser, I set the laser power level with a variable resistor and a mA meter. It worked, but it seemed just a little too iffy to me. If I moved my angle of view of the meter, I would see different readings. I couldn't help longing for a way to be more exact, more repeatable from job to job. Then I heard about the magical PWM. I didn't know what it was, exactly, or how it worked, but I was hearing that it was the modern digital approach to managing power levels in your laser. I'm a modern kind of guy. I'm a digital kind of guy. Sounds like just what I was looking for - or was it?