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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

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1 Answer

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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.

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It's a module with a current regulator built in, not just a diode. Given this, would a series resistor be ok? According to my maths the resistor will be between 50-133R, seems like quite a large range to me. – JimmyP Jan 15 '12 at 14:29
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@JimmyP - Can you link to the datasheet? – Oli Glaser Jan 15 '12 at 16:37
Couldn't find a data sheet, only what was provided above. I've treated it like an LED and added a series resistor, hooked the meter into it and everything's working as expected. Cheers. – JimmyP Jan 23 '12 at 9:59

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