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
With high power lasers, there’s always a safety concern for equipment and people nearby.
(Of course, I’m not qualified to give a detailed analysis of what needs to be taken into account for laser safety. For that, you should consult a laser safety officer.)
I want to specifically ask whether there’s an issue of laser light reflecting off power measuring equipment.
In applications where a human observer is involved (for example illumination applications), it is often important to measure using the eye-response-matched Photometric system of units. Ophir’s PD300-CIE is a photometric sensor, and is designed to measure illuminance (in units of Lux or Foot-Candles).
A clear benefit of knowing the M2 of your laser is getting a lot of information about beam quality all in one number.
As simple as the output is, it is harder than you may imagine to measure and calculate M-Squared.
Let’s take a quick look at the theory behind M2 to see how it can be measured.