Profiling small laser beams and measuring the beam size (or mode field diameter) can be a serious challenge. But it’s critical to measure, especially in such applications as fiber optic coupling efficiency, defect scanning, optical design and optical fabrication process control. Here’s how we suggest you do it
We’d all like to imagine that our things will stay in mint condition forever. But we know that’s not the case. Just like laser degrade (and therefore must be measured), the measurement equipment itself will slowly drift away from its precise calibration.
This is why we recommend yearly calibration. If you aren’t sure when your laser power or energy is due for recalibration, you can check by connecting it to a meter. If it needs to be recalibrated, a notification will pop up on the first screen.
Here’s how the recalibration process works.
What’s M-Squared, again?
If you’re not familiar with M2 already, it basically sums up your laser beam quality in a single number.
M2 takes a look at your beam caustic (the curve of the laser beam as it focuses and diverges again) and compares this to an ideal Gaussian beam caustic.
So if your beam is perfectly Gaussian, you’ll get M2 = 1. For high quality beams, M2 might be 1.1 or 1.2, for lower qualities you can get up to 3, 4 and even double digits for some low quality high power lasers.
So, how do you know what the M2 of your laser beam really is?