No matter what I try, I can just not seem to get my laser aligned. I believe the issue is with my 3rd mirror. The other mirrors should be fine. I’ve made a video of me trying to align the 3rd mirror and the result I get. Any help would be SO appreciated.
The video should be viewable now.
I may be thick as a brick, but the fact that it’s not cutting through a chunk of wood seems to have nothing to do with beam alignment at the third mirror.
What result are you expecting and why does that depend on the alignment?
Let’s start from the beginning.
Upload good pictures of the beam scorch on tape (or, better, paper targets) at the entrance aperture of:
Given those three pix, we can verify the beam is making it to the laser head in good order.
Then you should be able to assemble the laser head with a paper target at the lens position, center the beam on the target, install the lens & nozzle, verify the beam comes out the middle of the nozzle, and you’re done.
Start with the beam into the head and we’ll go from there.
In addition to what @ednisley writes, it could indicate that your nozzle may not be perpendicular. There have been a few posts on the subject here lately.
I can’t see if your machine bed can be raised/lowered, if so, make a test shot with a distance of a few mm to a test piece, you must not move this test piece, lower your machine bed a fair bit (min 100 mm) and shoot again . See if you get one or two points as the result. This test can be done with or without nozzle/lens.
Here are the dots on tape on each of the mirrors. I made separate burn marks far and close so you could see the quality of the dots. The close and far dots do line up when on the same tape.
It is subjective, but for me it is not 100% ok.
… have you tried sticking tape on the outlet of the nozzle? or have you done the test I recommended, to make sure your nozzle is perpendicular. Even if you only hit the inside of your nozzle a little you will miss this energy.
You do not write how much Watt you are dealing with.
Have you done a regular ramp test to find your focus?, on the video it doesn’t look optimal.
Excellent!
The Mirror 1 scorch is rather far off-center, which you can fix by moving the whole mirror mount. At this point, that’s not worth doing, but the next time you do an alignment, start by centering that one.
The beam enters the laser head off-center by enough to need fixing, which requires moving the laser head on its mounts to catch the beam in the middle of the aperture.
Do not change Mirror 1 and Mirror 2: they’re fine.
When that’s done, adjust Mirror 3 to put the beam in the middle of a paper target replacing the focus lens.
Install the lens, reassemble the nozzle, stick tape on the nozzle exit hole, and verify the beam punches through the middle of the hole.
Then run @bernd.dk’s test to verify the laser head and beam are perpendicular to the platform.
Then run a ramp test to verify the focus position.
Report back on all those steps so we can look over your shoulder …
Maybe it’s just me, but it looks like the beam diverges more than it should between m2 and m3, marked with a red line.
There is no way to tell the beam quality as these are just black spots for all practicality. Less power and/or shorter pulse time.
However, the right hand one seems to have less power near the middle, green arrow, than around it’s edge.
One of the issues is how big in diameter is the full size beam. You’re right, this would be unacceptable to me as far as doing a proper alignment.. It should be easily fixed, it’s not like these alignments routine require an education level of brain surgeon, it’s not rocket science either.
In his video, the laser lines seem out of focus, cut seems thicker than I’d expect.
At this late date we may never get the rest of the story; I figured making the beam come out the middle of the aperture would at least move the story forward.
There does seem to be more divergence in that last spot than there should be and I don’t like the beam shape, either.
Is it just me or have we seen a lot of tubes that don’t seem to be resonating in TEM00 lately?
I think my latest tube has caught the bug, so to speak…
Replaced the original OMTech tube … I thought it had been less than a year. Had terrible performance, so I checked alignment. Looking at the spot before m1, it was very small, maybe 1.5mm and had moved – off center.
Two pulses to m2, near, green, far, red. Far pulse shows the departure from TEM00. Bummer, though it’d been close to a year, but I put this tube into the machine in January 2023 … who knew? Tube was manufactured in November of 2021.
When I pulsed on m2 at the far distance, I could see the doughnut shape… so I ordered another one from Lightobject. This new ones 50W, 1000mm in length, so I’ll have to figure out how to handle the part sticking out.
The near spot looks very similar to the one taken at m1, but the far shot shows the failure. Funny, this was aligned to the center last time I used it ???
So I guess you’re right 
It might be like Capacitor Plague: all the tubes manufactured during a few (?) years share a common problem. They all share the the same ancestry and the same fault, regardless of the brand name on the tube sticker or box.
For all I know, all tubes come from the same (group of?) factories.
Why am I suddenly afraid to venture into the Basement Shop:trade_mark:? 
