How do I measure power?

How do I measure the power going to the diode (mA I believe) and how much it is emitting (mW)?

power to the diode you can't really measure easily without dismantling things. You need a multimeter to read voltage and amps. voltage*amps = Watts, a unit of power.

Measuring laser power takes a power meter. They are general expensive though. A half decent name brand setup will run you $400 and a decent name brand setup will run you into the 4 figures. You can get lesser meters for $100+. In any case, if you just have a single laser to measure you may want to pay the shipping to send it to someone else who can measure it for you.

Spin -- If you are gointg to make lasers a hobby, you will need AT LEAST one DMM and a power meter. Tools of the hobby
Mike

If you made your own and used a DDL driver, here's a link on how to test it for voltage and milliamps:
http://www.laserpointerforums.com/forums/YaBB.pl?num=1197651171
The four diodes have a load of 2.8v and simulate a LD.