I have been engraving water bottles for over a year but recently I am having a problem with the image and lettering being out of focus. I normally run the laser at a speed of 400/mm second and 70 percent power but this time I have what appears to be an out of focus image. If I slow the laser down to 50/mm second and 50 percent power the problem becomes less noticeable but is still there. I have read that the y axis belt needs tightening as well as several other things that may be the problem. I have attached photos of the problem as well as a photo of the Cut & Layers. I am using a Thunder Laser Nova 24 60 watt laser with a Ruida Controller. Any help would be appreciated.
Check your TEM resonance on your tube at m1… right photo is how I do it on mine.
Mine had a few weird issue when it went south…
There appear to be other issues and it may be related.
It’s definitely not a focus problem, because the lines are not blurred. They’re misplaced, which is a different issue.
Normally, I’d immediately suggest something’s wrong with the Scanning Offset Adjustment values, but this seems like a different problem.
Make sure that you have not inadvertently disabled or enabled the Scanning Offset Adjustment. Either change could cause the errors you see, but that switch is pretty well tucked away in the settings and unlikely to change on its own.
If it’s still set as you expect it and the table entries seem familiar, you could try measuring and updating the offset at speeds from about 50 to 500 mm/s to see if that improves the situation.
If that doesn’t help, then I think @jkwilborn has tagged the real problem.
Thanks for your reply. I read the article on TEM Resonance and don’t understand it. Also, you mentioned the “right photo is how I do it on mine.” I don’t understand what I am looking at. Any further explanation will be appreciated.
Thanks!
The laser beam needs to operate in a TEM00 mode for it to function properly… This is a 3d view of the power across the beam in the classic Gaussian power distribution.
If you view it down the Z axes it looks like…
What you see on a target is the burn area related to how power is distributed across the beam.
I put a target between the front of the tube and mirror 1 (m1). Pulse the laser, enough to produce a brown burn area… Can’t tell anything from a burnt hole…
A TEM00 mode allows the lens to work properly…
Although the left photo is from m2 and has a short distance, far distant mark for alignment you can see the right one shows it’s resonance or power distribution is not correct. The one on the right is from the m1 position…
Not only is it out of TEM00 mode, it has moved from dead center.
Hope this makes sense?
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