Components needed to control an external laser diode with Arduino

Projects General Guidance
1

Hi everyone,

I’m using an Arduino Uno and want to control a 632 nm laser diode so it can be turned ON and OFF through the Arduino.
The laser diode will be mounted externally on a holder, not on the breadboard .I just want the Arduino to handle the switching part.

I’m a bit unsure what components I’ll actually need to make this work safely and simply.
Could someone please explain:

  1. What parts I should get for this setup?
  2. How they would roughly connect together?
  3. Any tips to keep it simple and safe for a beginner?

Thanks in advance for any help or advice!

2

So you have bare HeNe diode or some module? Explain little bit more about your setup.

3

A bare laser diode need some kind of driver circuit. Sometimes it's just a current limiting resistor (like what's used with a regular LED) or sometimes in a cheap laser pointer it's just the internal resistance of the battery.

Usually laser diodes have an internal photodiode and a 3rd connection so the driver can monitor the actual light output and keep it constant. A better circuit will monitor the actual light output in a feedback loop.

Laser Driver Basics.

Once you can power the laser correctly you can use a relay or MOSFET circuit to turn it on & off with the Arduino.

Depending on the application you may also need a lens assembly.

If you buy a "module" all of that should be built-in.

4

If you mean you have a 'flashlight' like device, then open it up and connect wires to either side of the existing switch. Run those wires back to a small relay and connect them to G and NO. Now connect the relay to the Arduino per usual, and a couple of lines of code will turn the relay on via a push button.

5

Please post its datasheet.

6

I have always found that this gives very comprehensive information about this topic.
Driving Laser Diodes.

In fact probably gives you more information than you need but it is a big topic.

7

First we need to know the power.
Is it 5mW?

9

It is 13mW

10

Do you have a datasheet for the LASER diode?

11

Post a link to the data sheet.

12
13

None of those diodes are 13mW or even 632nm

Do you actually know what you have?

14

Sorry my bad, this is the laser I’ll be using

15

So this is a link to the manufacturer's specification

https://docs.rs-online.com/b337/0900766b8155d397.pdf

where you can read details about power supply, output power control and the use of PWM ("The Survelase Maxi laser is also available with a TTL driver board that allows the unit to be gated on and off, or pulse-width modulated at TTL voltage levels via the yellow control lead.")

However: This laser module is not unconditionally eyesafe!!! This is the classification as provided in the spec listed above:

image
image321×301 27.9 KB

You are responsible for a proper laser classification of the device you design ...

The laser module is designed to be use by professional persons!

Unfortunately the risks of using laser diodes are highly underestimated ...

P.S.: Just to get an idea please read this
https://www.repairfaq.org/sam/lasersaf.htm#safcils

(Many thanks to @Grumpy_Mike for linking this brilliant page!!!)

16

You can control it directly from any Arduino
All you need is a 5V power supply.

For an Arduino Uno:

Red wire -> +5V
Black wire -> Arduino GND and 5V supply GND
Yellow wire -> To any Arduino pin