Tuning the scanners

[rfourt]

Hello ppl i have now started to tune the scanners. its a nightmare for sure. I like it but i got some big problems.

1. in the scanning tuturial it says:
Set the scan speed to 30Kpps, and load the pattern. Now slowly adjust the scan angle setting in your software and watch the center circle in the test pattern.
Where is this.? im using "Easylase Usb Tester" software and cant find this Angle setting nowhere?

2. on my scanner "50k Scanners from Laserworld" i have 4 different pots.
Size, gain, HF, LF and position, linerety, offset.
The G, LF and HF are all back to zero, and then it only displays a dot. if i higher them i get some terrible looking testpatterns.

3. the scan angle, where do i control that,? With Gain or with size?

4. The scan angle counting.. gets us really confused. 8% scan angle width a distance of three meter would that mean that the image is 42cm in width?

I can say that the settings/pots are really messed up by me, meaning i guess its really way out of good settings.

And i have a hardtime even getting some results.

Or hold on,. my friend. Andreas sitting next to me now and tuning manage to get this: (see attached picture.) but we are running the ILDAtestpattern12K at 10k.

thnx for any help. (7hours and counting. )

Regards.

/Rickard

[whiteg]

Hi,

TUNING-TUNING-TUNING

Help me,
How to "repair" tune scaner?
My LW-50K Scaner Tuning Photos.
(30 000PPS MambaBlack, blanking shift:4, End/start point: 4)
Thanks

whiteg

[mccarrot]

Looking good
But Mamba isn't the best program to run the testframes, as mamba handles the scanner no that nice. try to use the test tools supplyed with the DAC

[buffo]

1. in the scanning tuturial it says:
Set the scan speed to 30Kpps, and load the pattern. Now slowly adjust the scan angle setting in your software and watch the center circle in the test pattern.
Where is this.? im using "Easylase Usb Tester" software and cant find this Angle setting nowhere?

I don't know anything about that software. However, if you have the EasyLaseUSB DAC, then I assume you have Mamba or Mamba Black as well, right? If so, then at the bottom of the screen there are controls to adjust the size of the scanned image. (I think you need to click on the Geo button first, and then that will bring up the sliders for size, as well as the ones for geometric correction of Keystone, Shear, Rotation, etc.)

If you don't have Mamba, then you need to figure out how to adjust the scan angle in whatever software you are using. But this is a *software* setting! It's got to be there somewhere.

2. on my scanner "50k Scanners from Laserworld" i have 4 different pots. Size, gain, HF, LF and position, linerety, offset.

Huh? That's 7 pots, not 4! Are you sure you're turning the right pots? (If you're not, you're really in trouble...)

The G, LF and HF are all back to zero, and then it only displays a dot. if i higher them i get some terrible looking testpatterns.

When you get all the way down to the dot, you are at zero. Then you tune up from there, just like the tutorial talks about. Use the quadrature square wave pattern first. Add a little gain on each axis until you have something that looks like a square. Then add some more gain until you see overshoot on the corners. Now add in some LF damping to get rid of the overshoot. Then more gain (which will give you overshoot again), then more LF damping to get rid of the overshoot.

Continue doing this on both X and Y until you get to a point where, when you add in the LF damping to get rid of the overshoot, you start to see some undershoot develop. To get rid of the undershoot you need to add a little HF damping. But don't over-do it! You want a nice sharp square connected by 4 bright dots at the corners.

One you get to where you have to add some HF damping to correct for undershoot, it's time to switch to the ILDA test pattern. Then you'll be able to monitor the circle as well as the square. All of this (and much more) is in the tutorial. Just follow it step by step and you'll be fine.

One thing though: are you 100% positive you've identified the pots correctly? Because if you're turning the wrong pots, then you'll totally screw the tuning up, and my tutorial won't help you fix it.

3. the scan angle, where do i control that,? With Gain or with size?

Different software packages call it different things. But don't confuse the scan angle setting (or scan size, or image size, or output gain, or any other term for it) in the SOFTWARE with the Servo gain pot on the scan amp. They are two separate things.

Note: There *is* a pot on most scan amps called "Input gain". (On your scanners, it's probably the "Size" pot.) This can be used to adjust the scan angle, and it won't affect your tuning. However, the standard procedure is to have this control set fairly high, and then adjust your scan angle down using the software setting.

4. The scan angle counting.. gets us really confused. 8% scan angle width a distance of three meter would that mean that the image is 42cm in width?

Yes. Exactly. For more information on calculating the scan angle (including a helpful table), have a look at the Pangolin website where they have a page devoted to Scan Angle calculations.

my friend. Andreas sitting next to me now and tuning manage to get this: (see attached picture.) but we are running the ILDAtestpattern12K at 10k.

OK. First, you need to be running the scanners at 30K, not 10K. (Unless you plan to always run the scanners at 10K, that is.) You tune your scanners for the speed you expect to run them at. And although your scanners are supposedly rated for 50K, it would be better to run them at 30K and enjoy a wider scan angle.

Second, from the picture you posted it's clear that you don't have anywhere near enough LF damping. See the overshoots on the corners? LF damping will correct that.

I'm really starting to worry that you are turning the wrong pots. It's fairly easy to correct for gross overshoot like that. It should only take a 1/2 turn to 1 full turn at most.


WHITEG:

It looks like you're scanning too wide. Reduce your scan angle to around 5 degrees and see if the center circle looks better. Then re-tune from there. (It looks like you have too much servo gain on both X and Y... Need to walk them down a bit.) Also, you need to look at the laser media test pattern to see if the scanners are running at the same speed or not. (You didn't post a picture of that pattern...)

Note: If you try to tune your scanners with the scan angle set too wide, you will *not* be able to tune them correctly. You don't want them running as wide as possible.

Adam

[whiteg]

Hi,

Thanks for tips Adam!

whiteg

[p1t8ull]

I found the LW manual was wrong on a couple of sets I have played with... the HFD and LFD were the opposite way round.

[tocket]

If you need help with this I can swing by and see what I can do with your scanners, since we're in the same town and everything. I have 45K laserworld scanners myself that I have tuned. I'm no expert, but I managed to tune mine from scratch to a decent state.

[h2so4]

Hi!
I'm experiencing great problems tuning my LW50k...
I tried setting everything to zero and tuning from scratch. Could someone please give me a link to download the quadrature square wave pattern? I think I've got a problem with it as I don't see a piece of the square. By the way, I managed to get something which looked like a square but what I think is undershooting, is really strange. After some time increasing gain and LFD, i seem to get undershoot but it doesn't look like the pictures in the tutorials, but more like a kind of wave near the vertices. Anyway, I switched to ILDA test pattern but didn't manage to get the correct circle. The phenomena I see on the square from some time on seem no more "under/over shooting" but some kind of "nodes" of drawing at the vertices and the outer (big) square has quite-rounded borders. Then, I think something got wrong and the Y galvo went in resonance and the mirror almost "exploded". Now I am going to use the replacement mirror but at the moment I don't have the glue and the shops are closed. When I am done with the repair, I'll need tuning? Any advice? I am really worried about this. I use the scanners for beam shows so I don't need very accurate tuning but at least I need something "acceptable". Could someone who has messed up with these scanners provide me some advice about tuning them from scratch?

Thank you very much!

Al the best!
Giovanni

[whiteg]

Hi

I tried tuning my scanner following Adam's tutorial, more times.
I'm not happy.
Maybe I'm waiting to much from LW-50K, but short lines always wave.

whiteg

[h2so4]

Isn't LFD and HFD swapped in that last picture? I've managed to do something which poorly looks like "tuning". The circle is far from fitting in the square, but at least beam patterns seems acceptable. The point is that if I tune to get something acceptable in the ilda test pattern, the rest is horrible and if I tune to see other images correctly, the test pattern looks horrible and the galvos seem crazy! The pattern in your second picture could scarsely be recognised. I am really disappointed with these scanners...Maybe I'm doing something wrong?