If you’re a serious laser user, you’ll know how important it is to measure certain laser parameters. Of those parameters, laser power is the most simple way to understand your laser. With the help of Ophir’s blog post – the beginner’s guide to laser power measurement, let’s talk about the first step in setting up a laser power measurement system – choosing the tools you’re going to use – the meter, or interface, and the sensor.

The meter, or interface, measures electric current, and displays the result. Ophir has a whole range of meters and PC interfaces, to suit any setup. There’s a link to the full list in the blog post.

Then – there’s the more complex choice – the sensor itself. The sensor must measure laser power accurately, and convert it to electric current – as that’s what the meter, or interface, reads.

If you’re looking for an easy way to make this choice – you’re in luck. There’s a link in the blog post to Ophir’s sensor finder, which allows you to enter your laser’s parameters and find the ideal sensor for your system.

What’s going on behind-the-scenes to generate these ‘best matches’?
Well, to start off with, there are two types of sensors to choose from – photodiodes, or thermopiles. What’s the difference?
If you have a low power laser, you’ll need a photodiode-based sensor, known as a PD sensor – for one simple reason – it’s the only type sensitive enough to measure lower power lasers.

And conversely, a thermopile-based sensor, or thermal sensor, is less sensitive, but can measure far higher powers – making it the choice for high power lasers.

When it comes to lasers with continuous wave beams, there are three crucial parameters that need to be considered, for either type of sensor.

First, the sensor must be able to cover the wavelength used by your laser. Secondly, the sensor must work well for your laser’s power range. And finally, it must be the right diameter, so that it can fit into the laser aperture.

For pulsed beams, things get a bit more complicated, but that’s a story for another day.