Aligning a fiber laser-

So it's pretty easy to align a C02 laser, at least the knowing-where-the-laser-is-firing part; when hit with a C02 beam a piece of blue tape turns white, regular paper turns brown, etc., makes it easy to tell where the beam's hitting your mirrors and lens.

Not so easy with a Fiber, since blue tape or paper does literally nothing when hit with a fiber beam...

My Triumph fiber laser has been acting like it's power output is dwindling a bit. Awhile back I made a 'random' adjustment of the laser's main 'snout' at the end of the optic cable, and pretty sure I messed it up a bit when I did. Also, due to all the working space I have (NOT!), my laser's cabinet has been smacked pretty hard a few times by random thing's being carried about the shop.

About a month ago I got into it, removed the scanhead, and surveyed the situation. Anyone who's pulled their scanhead and looked at it close knows that the horizontal 'tube', aka the beam's pathway from the snout to the scanhead mirrors, is pretty small. I didn't take a measurement but it's somewhere between 1/4" and 3/8" in diameter--
the 'tube' is the smaller of the 2 larger holes:
Attachment 469818
The trick is to make sure the beam is running as dead-center, straight and level thru that hole as possible, so that no part of the beam is hitting the 'tube' itself, which will absorb the light and reduce the beam's power density.

I DID find something I could stuff into the hole that would visibly show me where the beam was hitting: a piece of Magic Eraser! When hit with the beam it will melt slightly. I drew a big box on screen and hatch filled it, and set it to run at 100 speed an zero power. To get AT the tube in the first place the scanhead needs to be taken off. I simply held it in place with my hand when firing the laser-- I started it with the F2 button, then almost immediately stopped it with the ESC button. Took a few tries to figure out long to let it run to get the Eraser to start melting. When it did is left a near perfectly spherical depression in the eraser! And the depression diameter wasn't a whole lot smaller than the tube diameter! And my first test showed the beam was too low and right, it WAS 'bumping' into the side of the tube slightly--

The snout's mount has small adjustment screws for adjusting the azimuth & such, and I got it to hit the center pretty good. Then I had to spend an hour putting the head back on, and re-aligning the RED laser to match where the main laser was engraving...

But, I noticed the red laser was hitting the first mirror quite a bit above (what I considered) the mirror's vertical centerline. So over the weekend I decided to attempt to re-align both the red and main lasers. So I removed the mounting block (the dashed outlines I added to the pic above) from the scanhead and screwed it back onto the machine. It was now just a matter of making sure the beams path showed as dead center as possible at the bigger holes...

I was curious as to whether some clear strap tape would "show" where the main beam was hitting it, so that's what I covered the holes with. I ran a test fire at zero power, and nothing showed after a few seconds. Then I raised the power in 10% increments until I got to 40% power, for about a 3 second on-time, and got nothing on the tape. But the red laser DID show up on the tape, and it was WAY off. But the tape made it very easy to get the red laser centered up nicely.

To test the main laser, I measured the bigger hole, it was exactly 5/8" diameter, so I cut a bunch of 5/8" circles out of Rowmark, then took a 1" x 5"-ish piece of Romark, and added some double-backed tape to it. I taped a circle to it, fit the circle into the hole, then ran the laser for a couple of seconds at 30% power,
it worked nicely!
Attachment 469819

--and this is the BACK of the same circle-
Attachment 469820

--I ended up getting it closer than this, and it seems to have helped! And the red laser hits the mirrors much more to my liking!

Had to do the re-align the red laser thing again, but I think it was all worth it...

HOWEVER---

Turns out I did a big no-no, and I didn't find out till like the next day, when I went into the garage shop while it was light out,
and found ----
Attachment 469821
---look at the towel covering the door...

Yep. I had NO idea that while firing the laser with only the clear tape over the hole, that I was burning holes in the towel 7' behind me!!

--and the black drape beneath too--
Attachment 469822

-- the beam likely ended up hitting the neighbor's garage door, although I couldn't find that it did...

Last thing I (or anyone) needs to do is set their house on fire with a laser--!
And 40% of 30 watts is all of 12 watts, and even un-focused it did this....

So be aware of where you point these things! I got lucky... this time...

But the laser works great! ;)