co2 laser tube dirty on inside of output lens/glass

I have a 60watt chinese laser tube that is about 1 year old, probably has about 400 hours on it or so

i have been getting poor reduced quailty cutting on thin plastics that i cut,

cooling is always good, mirrors are new and clean, and alignment is very good also

but i did notice that when removing my laser tube, where the laser comes out, on that back side of the glass or lens that covers the end of the tube there is some discoloration, i dont know if its the coating thats damaged or if there is gunk on the inside of the lens

Is there a way to attempt to clean this? there are two water ports right there at the end of the laser, and I wondered if i could use something like a pipe cleaner or such, just something that wouldnt scratch though, and fish it through those water line holes to get to the back side area of that end, they seem really close but i dont even know if that water path goes right up against that lens/glass cover or not, it looks like it may but there could be a gap for all i know.

has anyone had this or figured out a way to attempt cleaning it?

also, i know i have run mucky distilled water through here from time to time, so I am going to be sure to not let that happen anymore but I dont know if that is what has caused this or not, I dont want it to happen more or again obviously.

Please let me know if you have any ideas, It is cutting bad enough that if i can't find a way to clean it, i will probably have to replace the tube, but with such low hours, i would like to try and save this one.

you think its inside the tube? what do you have for cooling? put clean distilled water in what ever you use for cooling a chiller or bucket of water what ever. add a table spoon of Clorox bleach and run the water pump for a few hours, See if that helps. I always have a little bleach in my water, keeps the slime and fungus down.

There are really three tubes, the laser tube itself, surrounded by a water jacket, then the outer glass tube. If you have something inside the window of the inner tube, where the gas that produces the beam is, that is a sealed tube and cannot be opened (without losing the gas).

Yes, I knew there were 3 tubes, and from what you said the area of concern must be the end of the inner most tube, that the laser is in, and there is a glass cover at the end where the laser comes out, as in you could stick your finger in the end of the laser tube and touch this glass, but the thing seems dirty or discolored from the inside, and like you said, i cant get to it, ... do you have any idea if the cooling liquid touches the back side of this lens, wondering if i soaked with the right stuff if it might come somewhat clean. just a thought, from what i can tell, the liquid definately doesnt touch the back side of the lens, as that would be inside of the "laser area" where the actual laser is

As I understand it no coolant comes in contact with any of the laser's optics.

The best thing to do would be to upload a picture to your post. Without seeing what your talking about its hard to tell the correct solution.
I would try Berts idea first and than move on from there - Might be a simple fix if not, add a picture of the problem.

Dumb Question : Did your water hoses start out clear ??? - What color are they now ?? (If they look milky or any other color Change your water)

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Originally Posted by Robert Bonenfant

The best thing to do would be to upload a picture to your post. Without seeing what your talking about its hard to tell the correct solution.
I would try Berts idea first and than move on from there - Might be a simple fix if not, add a picture of the problem.

Dumb Question : Did your water hoses start out clear ??? - What color are they now ?? (If they look milky or any other color Change your water)

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The water is not in the tube with the lens. I use the pink RV antifreeze all year in mine.

sounds like the output coupler lens coating has failed on the inside on the cavity...pictures like Bert said though :) without it we are all just guessing