Running an OmTech 100w auto. I’ve had my laser up and running for about two months I started to notice the cut line was a little off. I started the alignment process starting from mirror three. It was centered and then aligned two both front and back. Three was in the middle after some tweaking. Once I pulsed it on a test piece there was a dot and a crescent. Tried to cut a small oval and came out with the image below.
It is possible the laser tube is misaligned vertically, so the unfocused beam (or some part of it) is hitting the inside of the nozzle and reflecting away from focal point.
If the laser tube is perpendicular to the platform:
- Stick tape on the nozzle and verify a manual pulse hits dead center
- Replace the lens with a piece of paper and verify the defocused beam scorches the center
If all those are good, then what you see is, I think, the symptom of a CO₂ laser tube going bad: it’s not lasing in TEM00 mode and emitting a beam that’s not a nice smooth Gaussian shape.
You can check the beam shape with a paper target at the entrance to Mirror 1 at the tube. If it produces round scorches at power levels from 20% up to your normal cutting power (with correspondingly shorter manual pulse times), then something else is wrong.
Show pictures of those test results to give us more information!
You can follow this post for checking the tubes TEM mode.
