How does burn pattern look

Here is a very short burn from my K40 right at the tube exit before any mirrors.

Does this look normal or is it off?

It could be but the picture does not provide any sense of scale?
Is this spot magnified?
Is there a particular problem you are trying to solve?

It’s zoomed in quite a bit, very small dot when looking with naked eye.

I’m getting a circle outline burn pattern after mirror 1 so I’m trying to figure out if its the tube and maybe get a replacement from where I bought this unit.

That appears to be a normal pattern from the tube. No TEM* pattern.

*Transverse Electromagnetic (TEM) wave. 00 = normal

Explanation here;

So it’s normal for the pattern to change into a circle outline after it hits a mirror?

This pic is closest after first mirror.

No, the pattern should not change. The shape of the beam should not be affected by the mirrors. If the burn pattern is a solid circle coming out of the tube, it should be solid everywhere it hits and be reflected as a solid circle.

A good test would be to swap your mirrors and see if the shape persists.

Did a bit more test shots, it’s a little tricky getting a nice mark without burning the paper.

Here are a bunch of shots at 9% power with me pressing the test button as quickly as I can.

Here is a good video to show the burn pattern right at tube outlet

For what it’s worth, you have a huge air bubble in the water jacket; tip it to one side to bleed that air off. Try it again after you bleed it down.


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Is there a particular problem you are chasing other than verifying that the beam looks right?

I just want to make sure I’m getting most out of this thing.

Where is the air supposed to go, those tubes aren’t sealed?

When you rotate the machine the air exits out the top of the water outlet.
I have to pick mine up and rotate the entire machine…not pretty.
No, The water jacket in the tube is not sealed.



Your laser spot looks ok, but with this air bubble, your laser tube will not survive long.

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THX for an important tip

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