Got my GF today (yay!). While going over it I noticed a mark, or scratch, or something, on the window on the gantry. Thinking it was dust, I gave it a gentle wipe with the zeiss wipes, and some lens paper, but it seems it may be a scratch in the window? Not sure. I didn’t scrub hard as I don’t know how soft that optic is (ZnSe?), so it’s possible it’s a goober of some kind. I suppose if the beam is tightly focused as it passes through it may avoid the spot, which is fine.
ZnSe is pretty soft. Do you have a blower of some kind? Something that will give it a concentrated, direct blast of air? Looks almost like a little piece of foam, but as you said, it didn’t wipe off. Alcohol acts as a solvent so it should eat it up if styrofoam.
As far as the cleaning, it should be gentle but I personally haven’t used “kids gloves”. Some of the backspatter has taken a little bit firmer of a wipe to remove and my optics seem to still be ok.
The lens is (maybe) ZnSe as it’s a common lens coating for low power CO2 lasers. But the gantry mirror windows I wouldn’t expect to be so. I’d use my fingernail to see if it will come off.
Small stuff like that degrades your beam and you lose some power. It still works but you’re taking a loss. Long term, I’d say it needs to be cleaned or replaced. We’ll see what support staff says.
Specs on common co2 laser tubes show ~2.5-3mm beam diameter. If it is not yet focused down smaller, and is centered on the window, then based on a quick and dirty analysis the spot does fall inside the beam:
If the window does just unscrew as @rpegg mentions, then it would be simple for me to swap it out. Assuming it wouldn’t throw off the calibration! With a refractive index of ~2.4 at 1062nm, it could be touchy.
I suppose I can try cutting some proofgrade, and if it cuts completely through and is consistent, then any small power loss is tolerable, and it wouldn’t be worth fiddling with it. It’s only about 4% of the area of a 3mm circle. If it ain’t too broke, don’t fix it =)
Haven’t replaced one. Don’t think calibration is an issue as long as it is in place. A transparent window at these wavelengths. The company sells replacements in the shop.