1-Disconnect the diode from the driver.
2-Discharge any caps in the driver circuit.
3-connect the digital multimeter in series with the diode and the driver.
4-turn laser on and look at reading.
5-turn laser off and again discharge any caps in the driver before reconnecting the diode.
Checking the current going into the driver is a lot easier for obvious reasons.
An easy way to measure current over and over is to just put a 1 ohm resistor in series with the LD. All you have to do is measure the voltage across the resistor where 1mV = 1 mA, that way you don't have to keep taking your circuit apart if you adjust the pot or swap resistors on your driver.
For anything (expected) under 200ma, under DCA set to 200m. Anything greater than 200ma (expected), 1 click down to 10A.
You have to plug the + lead of the tester into either the 20m or 10A holes. If you test at 200m and what youre testing is above 200ma, you will blow the fuse or burn the meter. Make sure your MM has its test leads plugged in correctly.
Set the knob to the 2000m setting, connect the diode to the driver (remember to short out the capacitor) get a 1 ohm resistor and place it between the positive wire coming from your driver and the positive pin of the diode. Then take your multimeter and place the + probe between the driver and resistor and the - probe between the resistor and the diode. Set the pot to its maximum resistance and power up your driver, slowly turn your pot down and you should see the reading on the multimeter start to go up. When it's set on the 2000mV setting it should display like this: 0.000 so if you get a reading like this: .250, the diode is being driven at 250mA.