I’m using a MOPA laser with LightBurn to etch a logo on 20 parts within a 220mm x 220mm area. Despite having an accurate CAD model and jig, the logo isn’t centered on the parts. My supplier mentioned that the middle position should be fine, but the edges may be offset due to normal lens reflection. They suggested adjusting each position manually and saving the settings for future use. I don’t know if this is just compensating for a laser that is not properly calibrated. Any insight would be most welcome.
No, not normal, I routinely run right to the edge (and sometimes a little bit beyond ) without what I would consider focus issues. (Using a 60W MOPA, maybe different with 100W lens)
How close to the 220x220 edge are you noticing the out of focus?
What are the symptoms?
I don’t think calibration will (directly) affect focus with a galvo, may be a lens issue, but you should run a calibration on it for other reasons.
These are F-Theta lenses, meaning it’s a flat field lens. So I agree this shouldn’t affect focus. It does have limits.
It’s focal length is used to determine surface speed and size of image.
As the angle gets larger, closer to the edge, more of the beam is reflected that can cause variations. I’ve never tried the edges, I put a longer lens in the machine…
I did learn that the cost of a >=100W lens is about 8 times the cost of a lower power lens. One of mine that cost $60 is about $480 in the >=100W version, they apparently use a different type of glass… one of the reasons I stayed under the 100W level.
I would expect that the vendor sells a lens with certain coverage, it should do what you purchased it for. Selling you something that says it’s got 200mmX200mm, should work at those limits.
I just know the surface information about these, that’s about it.
Thank you for your response. So they are off by up to 1cm in areas even within the first 10cm square. The central one is in focus and others are not. Thanks again
Hello, Joseph I may have misunderstood, when you say out of focus it sounds like you are really talking about out of scale. That makes more sense and a full re-calibration should be performed. A 10x10 square should be 10x10 everywhere inside the listed working area. To me, out of focus would be square burning brightly in one area and not so bright in another area.
My terminology is wrong. Sorry for the confusion. The parts are still etched fine but the position of the logos is out of place even though the jig and cad is correct
) without what I would consider focus issues. (Using a 60W MOPA, maybe different with 100W lens)
