Odd Unfocused beam

[billturnbull]

Hey all,

I've had some cutting problems lately and found that the beam isn't very good. I've attached a photo of a test firing of the laser, about 10cm away from the laser tube.
The first time before cleaning was a rough dot with a circle around it.
I cleaned the tube lens with a syringe and ethanol as described on the EFR web page and it seemed much better, so I gave it another squirt of ethanol and it's back to the same as the first photo.

Has anyone got any ideas what's going on?

It's an EFR F2 80w CO2 tube.

Thanks for reading!

Bill



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[Dean448]

There are a lot of posts on this site showing weird burn patterns. Unfortunately they all lead to a bad tube. I had a tube that created a ring. The main culprit is running at too high a temperature or current or both.


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[billturnbull]

So, this morning I got stuck into it and removed the side cover and the output lens on the tube was filthy... I think the second squirt may have just washed all the grime back onto the lens as it had a kind of high tide mark!

I carefully and gently used a q tip and alcohol and cleaned the lens, guess what? Muuuuuuch better... A nice solid spot!

I'll do some cutting then report back...

(Still, I think we'll order a spare tube though...)

[vrc321]

>>output lens on the tube was filthy.<<

Sorry to be a newbie, but exactly where is this lens located? Just inside the hole at the end of the tube?

Thanks.

[rodrigomartins]

>>output lens on the tube was filthy.<<

Sorry to be a newbie, but exactly where is this lens located? Just inside the hole at the end of the tube?

Thanks.

is the lens that sits at the edge of the output laser tube equal in the image below...



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[vrc321]

Thanks for sending that. Not sure if mine has something similar on the end but I will check in the morning.

[rodrigomartins]

Thanks for sending that. Not sure if mine has something similar on the end but I will check in the morning.

all laser tubes have the lens in the output ... and you should clean it from time to time ... it is on the negative side of the tube ....

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[vrc321]

I checked it tonight and found the lens to which you were referring. I can't really see in there due to the position of the tube in my laser's cabinet but I took a clean cotton swab dampened with optical cleaner and went over the lens. Nothing showed up on the swab that I could see but it was a good thing to check.

Thanks.