A Quick Guide to Profiling Small Laser Beams

When using a camera to profile your laser, it’s important to keep the ratio of laser size / pixel size higher than 20. Not only does this increase the resolution of your profile image, but it also makes your measurements more accurate. (If you have fewer than 20 pixels in your beam, the measurement accuracy will be worse than 5%.)

Beam profiler cameras typically have a pixel pitch in the range of 5-10 microns, with the notable exception of pyroelectric cameras, which have larger pixels.  This means if your laser is smaller than 100-200 microns, you will most likely need beam enlarging optics to profile your laser.

There are two cases where the minimum beam size is less straightforward:

1. Pyrocam III and IV can be used with beams only 10 pixels wide, instead of the usual 20.
2. Phosphor-coated cameras for IR (all the cameras that end in “-1550”) need larger beams because the phosphor coating diffuses the light.

Here are the minimum beam sizes recommended for use with Ophir-Spiricon cameras, both with and without beam expanding optics.

What other challenges do you face with a small beam?  Let me know in the comments.