Galvo surpassing it's scan angle

[masterpj]

Hello all, I was lasering *safe off course and not standing in the beams*
during lasering I noticed something odd.
The beamshow was running at it's full scann angle, and as far as I know I was NOT overloading the scanners.
I'm also not overscanning.

However this is what happened:
A short burst of a projected pattern *but not deformed or anything* bursted way higher then it's scan angle!.
*then continued normally again*
this was in the vertical axis and has only happened 2 times (very rare)
and in both these situations this was only higher in vertical projection *not lower*

I'm using a 25 meter ilda cable, so that's known for possible causing slight distortion and a lower scanning angle of 2%, but certainly it cannot scan at a higher that much.
*difference was really much*

I really want to investigate this, it just doesn't seem normal to me.
and certainly I want to figure out what could cause this.
I want to be sure about my projector and also sure about it's reliability, I never want to risk anything.

Oh I should included this: i'm not using the projector for crowd scanning yet and am also not planning on doing that, only with supervision of someone that has more experience then me could be an exception.
I'm also carefull with my eyes at all times, safety is a number 1 thing on my list.


Anything I should know or should be aware of because this is happening?


Scanners are: LW50k
With custom amps.

Galvo's are ok and working great furthermore, no weird sounds or distorted images..... I really don't get it.
the scanning angle is 60 degrees.
but the brief burst was like more then 120 degrees?!!!!!

[danielbriggs]

The beamshow was running at it's full scann angle, and as far as I know I was NOT overloading the scanners.
I'm also not overscanning.

Probably were.
Self-resetting fuse may have sporadically kicked in on the Y axis...

but the brief burst was like more then 120 degrees?!!!!!

If it really was 120˚, it would clip the mounting block.


Conclusions...
Some of the many reasons why you can't and *shouldn't* rely on "software safety" be it BAM's, Zones etc.
Nothing like good-old black aluminium masks et al.

[flecom]

I have has this happen when you have a switching power supply that cant give enough current to the scanners...

the powersupply will momentarily "freak" and the result is a huge scan

or like daniel said, self resetting on whichever driver

[masterpj]

Probably were.
Self-resetting fuse may have sporadically kicked in on the Y axis...


If it really was 120˚, it would clip the mounting block.


Conclusions...
Some of the many reasons why you can't and *shouldn't* rely on "software safety" be it BAM's, Zones etc.
Nothing like good-old black aluminium masks et al.

It doesn't seem to have to do with anything of bams, it seems like my QM is faulty.
I'm also contacting bill about this *just did*
as my QM crashed ~4 times. since 3 days ago.

And yeah I will have someone look at this, preferably in the netherlands. I know I should work on it myself, but I really don't want to mess too much myself in my projector yet.
I would certainly arrange a payment if someone can check this for me

[danielbriggs]

It doesn't seem to have to do with anything of bams, it seems like my QM is faulty.

You have directly proved my point about non-software safety measures.


P.S. Is it a .NET or PCI version?

[masterpj]

You have directly proved my point about non-software safety measures.


P.S. Is it a .NET or PCI version?

PCI and I will send it back to bill for debugging.

[masterpj]

here is my projector scannhaaing the 30k ilda test pattern at full angle.
also I turned the output power down to 40% for the picture

the projected wall is perfectly straight



Also about the software, actually the projection BAm's actually stayed perfect at all times, and it has never failed.
I do know it's not smart to rely on software only, but other then the 2 times y axis jump the places I set no laser output to really never got a laser output
and even not at the jump the zone was still safe

[andythemechanic]

Hi,

I once had the same problem. It occured only some times in an nopredictable way. In my case it was the overheat protection of the galvo driver. When it was just at the edge of being triggered it switched one galvo off for a very short time and then on again. This looked exactly how you described your phenomenon. In my case it helped to reduce the scanspeed, get better thermal coupling of the galvoamp to the heatsink and lowering the supply voltage of the galvo a little bit.
You can check if the effect happens only after some time of hard scanning (ILDA test image at high angles for example is quite hard for the scanners). Then you can check if it gets better if blow with a fan onto the galvo amp. If yes it is very likely the same thermal problem.

Andreas

[masterpj]

First of all: thanks andy, I will try this and if yes.
I will pay someone to fix it for me

secondly:
the a wobbling line *as like a flag pole. doesn't always happen but only at some frames.

[allthatwhichis]

If you are using a QM2000, you may have set a frame to use projection zone 3, which is used for bounce mirrors and usually runs at 100% scan angle by default and is not changed by your main scanner size setting. Some of the beam shows like Melody, Paradise, and my beam shows use this zone to project beams way outside the normal zine size to hit bounce mirrors for added effect. You should be able to use the "advanced" frame window in LD2000 to see what zone your frame is assigned to.

You may also have zone 4 set to a larger scan angle and a lot of beam shows use zone 4 for atmospherics instead of zone 1. Check the size of zone 4 also.

Also use the 12K pattern at 30k to test; I am not sure what the purpose of the 30k test pattern is for since it is so small. Everyone I know uses the 12k test pattern at their desired scan angle to test.