Laser tube is firing a ring

I have a Preenex 100w laser that’s been used very sparingly since July 2020. Doesn’t have more than a couple hours of run time, mostly cutting thin plastics and paper at no more than 50% power but usually closer to 20%.

After FINALLY properly aligning the beam, it’s now firing a ring directly from the tube. I’ve seen posts about internal mirror alignment and possible gas leak issues but those posts are 10 years old. Any current ideas about possible solutions?

I had this exact problem, so I called Lightobject where I bought my Reci tube. They said this is normal at very low power. This does not seem to effect the beam after it is focused.

Two thoughts, First I will echo the lower power, it’s call the preionization zone. If you look at the tube when it’s at low power and firing, the end at the output will ‘dance’ in the tube. it’s completely normal and will straighten out as the power comes up.

Second, I get the exact same thing when my tube is cold. Granted my factory tube is a QC EFR F2 reject relabeled by KH.

My laser fires a ring always while aligning mirrors at low power. Its not an issue. Ring or no ring, once the laser goes into the lens, it will focus into a point.

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