What is causing this shadow. co2 laser 1 pass
Your profile says “ortur”, so it’ll help to know more about the CO₂ machine having the problem.
It’s probably a misaligned beam splashing off the inside of the nozzle.
Scorch some tape over the entrance apertures of all three mirrors. Set up a manual pulse on the machine console, perhaps 50 ms at 30% power, and fiddle with the timing / power to get a brown mark rather than a burned-through hole.
If the beam isn’t at the center of all three mirror apertures, then it’s time for a thorough mirror alignment. When you’re done, upload five pictures of the scorches at the four corners & center of the platform so we can look over your shoulder.
If the beam aiming looks good, then we explore other horrors. The nightmare scenario is a failing tube not operating in TEM00 mode.