Someone in a post about the above said “a picture of a hole is not helpful”. We have been doing our alignment by pressing the manual “pulse” button, which is obviously 100% power. Should we be trying t o assess the TEM at lower powers, or would that defeat the object?
Same person said they cut targets out of watercolour paper. Isn’t the “target” then some microns at least closer to the laser, but more importantly since the mirror is at 45°, some microns to the left or right? How much does the thickness of the paper affect the calibration?
In fact if we just want to test TEM, shouldn’t we have target that is perpendicular to the laser?
You can set the power on your Ruida Controller. I set mine for 15 or 20% and with a fixed pulse time as well, I think it was around 100ms, but you will need to experiment with both settings for your machine. That gives consistency in your testing.
I use construction paper or card stock since it’s a little thicker than printer paper or tape.
Thanks. Am I right in thinking that this is “diagnostic step one” and anything other than the TEM00 pattern means we are wasting time aligning mirrors, testing power packs, focussing lasers etc?
Sorry for separate replies but …I’m guessing thickness isn’t an issue for this test if we are perpendicular. Would that mean we can just use some of our waste 3mm MDF (of which there is plenty!)?
We make holders for miniature paint pots which result in about 30 or so very neat 25 mm circles. Waste to us, but I swear we could sell them to someone!
You are correct. If the tube isn’t working properly you will get poor results with everything else. This is a picture of mine before and after replacement. Exact same settings on the pulse. Guess which is after.
To be honest, I’ve done it both ways, and it doesn’t seem to make much difference. I say this because the target at M3 (on my machine) is on the same plane as the mirror, when I check alignment (I’ve also had it at 45°, no change). That being said, at M1, it would be best to have your target perpendicular to the beam when checking for TEM00. @jkwilborn has a useful response to this thread: Lost of power on our Reci W6 tube? - Community Laser Talk - LightBurn Software Forum, specifically post 2 and 4. I run my 60W (when pulsed) at 30% pwr and a pulse on time of 30ms (YMMV depending on your laser). This gives me a nice toasty brown spot that’s readable without blowing a hole through the paper. Jack likes watercolor paper, (I use cardstock), as anything thinner may just catch fire. Jack has a great number of good posts about beam quality and alignment on this forum.
