So, recently I was adjusting mirror alingment because my laser could not work on the right side of my work table (double line), only at left side. I alinged my mirrors succesfully, and my pulse was super clear and perfect round dot in all four corners. It cutted and engraved properly in all corner of the honeycomb. I worked at my laser for 4 days normally and at the end of every work day I would clean the mirror 3. with alcohol.
The problem came the 5th day when I turned on my laser and started cutting at the right side of honeycomb, it was producing double line just like when my mirror alingment has been messed up. I tested “near” and “far” pulse at mirror 1. - mirror 2. relation and it worked well but “near” and "far position at mirror 2. to mirror 3. was not working proprely, so the problem is in mirror 3 probaly I concluded.
What can cause this?
Can somehow mirror 3 move when cleaning?
Upload good pictures of the pulse tests at each mirror position, so that we can see what you see.
If the error is apparent at the entrance to Mirror 3 at the laser head, then the problem is due to something between the laser tube and Mirror 3.
Unless, of course, the entire laser head is loose and can move, which has happened due to stripped holes for the head-mounting screws.
Other folks have found loose mirror mounts, either the entire holder at the frame or the lock ring holding the mirror in place.
There can be other problems, but those seem most common. Take a very careful look to be sure all of the “immovable” parts really are firmly attached.
When something changes, especially like this, I suspect TEM resonance issues. Mechanical things, especially optical paths, are not going to shift out of alignment sitting overnight while you’re sleeping.
An alignment is only as good as it’s source, so check it at m1.
That’s the shape of an unfocused diode laser. The spot looks almost properly focused at the platform, so adjusting the red-dot laser pointer’s focus should tighten it up.
If that’s an integral red dot laser mounted on the CO₂ laser tube’s output end, then it may not be possible to adjust its focus without taking if off the laser, which you probably don’t want to do. The manufacturer probably pre-set the focus for a typical machine, perhaps not carefully, and your machine is on the edge of proper focus.
Now that is a problem.
Most likely, the screws have been backed out (loosened) until the entire adjusting plate is resting on the laser head. The springs look fully extended, so they’re not doing their job.
Spin the hex nuts midway up the screws, then tighten all three screws about eight turns to take up half the visible thread, which will pull the plate up the head and put the screws in compression.
Take a look at the other mirror mounts, because if one of them is that badly adjusted, you may have two more mounts to fix the same way.
Then re-align all the mirror you tightened so the beam exits through the middle of the nozzle as it should, which will (probably) fix the bad spots in that first picture and with the springs working correctly, the beam should stay aligned.
So, my red dot was perfectly round and clear on the platform before I did a mirrors alignment, after that red-dot pointer became a bar instead of a dot. On the picture it looks like a perfect dot, but in reality it looks more like a bar.
I will try to apply your steps, if there is any problem I will ask.
Obviously, something changed during that operation, so now you must figure out what happened. Fortunately, you can almost surely restore proper operation and learn something along the way.
For example, did you take the focus lens out of the laser head for cleaning, then replace it upside-down? The convex side must be upward.
I would start with tape on each mirror and pulse the laser near and far. Post the results. Look closely at the mirrors for any defects along the way. A few weeks ago I helped a guy that had a small scratch on his lens that blurred the results.
Yes I am 100% sure that my lens is on the correct side.
So, the best for me is to do the alignment again and try to figure out why my red-dot pointer looks like a bar, and also try to tighten hex nuts so the 3rd mirror is fixed?
Here is the hardest lesson I ever had to learn: I am sometimes completely and utterly wrong, which generally happens when I am most certain I’m right.
When you reassembled & realigned the machine, you know you did it right, but the evidence strongly suggests something went wrong.
The nuts prevent the adjusting screws from moving, but tightening them will change nothing when the screws are in the wrong position. Do what I suggested to move the plate holding the mirror where it should be against the springs, verify the other mirror plates are correctly positioned, align the laser beam path, then snug the nuts to lock the screws in place.
Take pictures of the targets (tape, paper, whatever) you use to verify the beam position and show us the starting & ending condition so we can check your work.
The shape of the mark at the entry of Mirror 1 helps verify the laser tube’s condition: it should be round and smoothly shaded.
And, as @micrololin suggests, carefully examine the mirrors and lens to verify they’re in good condition.
Today I did a re-alingment, and I noticed that the problem was at mirror 2 to mirror 3 relation, I did not finish the alingment. Tomorrow I will send pictures of pulses at each of mirrors so you can inspect if there is any issues.
The red-dot pointer produce the same bar as at the mirror 3 at mirror 2 and mirror 1, but at mirror 1 it is smaller and clearer. I will try to take some good pictures to you can see.
It is obvious thar mirror 2 to mirror 3 relation is not aligned, it was and I have no idea how that messed up. Also I did not managed to figure out why my red-dot looks like a bar. The beam also looks like a bar at mirror 1 to mirror 2 (far).
It was and I don’t know
The spot at Mirror 1 looks reasonably good, so perhaps Mirror 1 is damaged. If the mirror is good, then the beam shape at Mirror 2 confirms @jkwilborn’s suspicion the tube is not operating in TEM00 mode.
As I explained, a bar is the shape of a defocused diode laser beam. The red-dot module is focused to produce a small dot at the platform (about 1.5 m away through the main beam focus lens), but will be defocused at shorter distances (just outside the module at the main tube).
I initially thought the red-dot module in your machine is incorrectly focused at the platform, but damage to Mirror 1 could account for its shape.
Take a close look at Mirror 1 and upload a picture with the mirror reflecting a plain background so we can all see what you see.
I wanted to see the surface of the mirror, because I assumed the laser beam is properly shaped and the mirror was damaged, but this picture contradicts that:
Although the spot is round, the unburned area in the lower left quadrant shows that the energy distribution isn’t correct over the entire beam. It should be more intense at the center and taper off symmetrically around the perimeter, which it does not.
Everything is clear now, I understood you. I just have some questions for you.
How can laser beam cut and engrave on the work surface at the every corner almost perfectly (I do not know what exactly is perfect laser beam because I have had problems with the beam since I bought the laser) when the tube is not operating in TEM00 mode?
What can cause that the tube is not operating in TEM00 mode, for example my tube is not very old it has only like 400 hours of operating and I do not see the reason why laser tube would not operate correctly?
