I want to control the following laser module from an arduino digital output:
- Specification V2 – Aug 2010
- Wavelength : 650nm +/-5nm
- Output Power : 4-5mW
- Operating Voltage: V2 = 3.0-4.0V
- Operating Current: 15-20mA
- Operating Temperature: 10 – 40°C
What's the best approach – I've looked at diodes for voltage drops, resistors and regulators but I really don't know which to use. The variability of the voltage and current in the specs is rather confusing.
TIA
Best Answer
The best way is to use a dedicated laser driver IC such as the iC-WKL from Global Laser.
This will take care of the careful regulation needed. It expects a laser diode with an inbuilt monitor diode for optical regulation.
Other less ideal ways to drive them are:
A series resistor to limit current as you would with a normal LED - some more robust modern diodes can apparently be used like this quite successfully.
A constant current setup.
Laser diodes are usually very sensitive to variations in current/voltage (the lasing threshold is quite close to the maximum threshold so not a lot of room for error) so check your datasheet to see how much "play" you have.
This page has some good info on laser diodes.