Hi,
I assemble a new machine, DAVI 30W RF CO2 Laser with SINO-GALVO head’ I try to align the laser source with the optics. I have not finished and not satisfied yet, but I noticed a strange situation, I am sure that somebody with more experience have already seen this and can explain; the laser beam before beam expander seems to be round and after beam expander have an irregular shape (bigger size, ofcourse). If I move up/down or sides the laser, then the point move from the center but the irregular shape seam to remain.
Can I suspect a beam expander quality problem ?
Should I worry about the performance of the machine with this beam expander ?
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In some part it’s the fundamental nature of on and off axis behaviour of a laser going through a galvo, exacerbated by the larger spot size of co2 laser. Airy disks and whatnot. What’s the distance between the beam expander and the first mirror? What’s the beam expander power? What’s the spot size going into the expander, and what’s the size of the aperture of the galvo? I suspect you may have some beam clipping, which should reduce the closer you get to true alignment.
If it’s not going through the f-theta in those tests, then disregard. Blue tape isn’t a homogeneous material, and will be less than ideal for diagnosing pre opticis beam quality. The burn area looks “round enough”!
The beam profile of Coherent’s RF lasers like the Diamond G100 are elliptical, it’s in the datasheet. Gem 50/100 are also elliptical, but the 100 have external corrective optics after the window.
It generally doesn’t matter much if it’s uncorrected.
I say this because, like, the 60W DAVI D60 is CLEARLY a Coherent Gem 50. As far as I know, they may have just disassembled a Gem 50, measured everything, and copied it. It’s going to have an elliptical output. But that’s probably not your problem TBH. Clipping or maybe off-axis lens, or cracked lens?
I don’t have experience with the DAVI. Coherent RF lasers never mode hop from the TEM0,0 fundamental like HVDC-excited glass tubes, but if it’s a knockoff, who knows?
