How Can I Measure The Power Density Of My Laser?

Peak power, average power, power density, energy density… all of those terms can be quickly confused and mixed up even by experienced laser users. In this short article, we’ll focus our efforts on one of these parameters: power density. We’ll start with a quick definition and then we’ll dig right in as to why it’s relevant and how to measure it.

WHAT IS LASER POWER DENSITY?

The power density, as its name suggests, represents the quantity of energy in your laser beam per time unit per surface area. Usually, it’s measured in watts/cm². Depending on your application, it might be crucial that you stay below a certain amount called the LIDT (Laser-Induced Damage Threshold) so your optical components don’t get damaged.

It can also be the opposite; you need the power density of your beam to be high enough so it cuts through a material. See our laser beam profiler in action in the video below as HiLASE Center is experimenting with material limits!

If we think about pulsed lasers, we usually refer to the concept as fluence or energy density, it’s slightly different, but the fundamentals are basically the same. It’s the concentration of energy, instead of the power, in a certain area of space. But, let’s not get carried away here and keep the focus on power.