Hello All, Laser Question/Help

[jdavis7765]

First post on the forum but have been reading around a lot at various posts. There is certainly a wealth of information here. As an introduction, I am 33 years old and have just started breaking into the laser world, first with a purchase of a cheap laser from Aliexpress, Emma Laser EM-RGB24B. I have two questions. Can you push a laser too much with complex animations, more drawing more points, etc? I have been using modulaser and some of the designs seemed to push the laser galvos harder than others (whining noises). Is it possible to damage a laser controlling through an ILDA connection? Reason I am asking this is, it seems something went arai with my laser as it no longer will draw simple objects correctly, such as a circle. When more lines are drawn it has an even harder time keeping up and some lines are not drawn at all. I have reached out to their tech support but I fear the worse when dealing with a foreign laser manufacturer (I get what I pay for).This leads me to my next question, I wondered if this is something I have caused and if so, is there a way to fix it if the manufacturer chooses not to help?

I can post images or links if it helps. I was reading the post on tuning galvos, but not sure if this is the issue. Also, I did test using ILDA interface as well as simple animations from .ild filed on the SD card and both had the same issues.

Thanks all for the help and Happy New Year!

[jdavis7765]

Here are 3 test pattens from .ild files I found from here https://www.photonlexicon.com/forums...Scanner+tuning

[VDX]

... much too fast for your galvos ... and yes, you can damage them, if pushing into resonancy and/or hitting the mechanical limits ...

Viktor

[jdavis7765]

... much too fast for your galvos ... and yes, you can damage them, if pushing into resonancy and/or hitting the mechanical limits ...

Viktor

Thanks for the reply Viktor! So, these galvos could have sustained some damage with my output then. The scanner is 40kpps (according to purchase description) and was working great, can't scan much at all now. Are there any adequate ways to limit damage when controlling through ilda in an app such as modulaser? Wish there was some sort of governer switch so you wouldn't exceed these limits. As far as repair, I know it may not be an easy question to answer, but would tuning possibly correct or would I potentionally need new galvos?

[VDX]

... some images of your setup? -- didn't sound like 40kpps or even 30kpps ...

Viktor

[jdavis7765]

... some images of your setup? -- didn't sound like 40kpps or even 30kpps ...

Viktor

Images of the inside? If so, going to wait for response from seller before opening chassis (tamper sticker). If this helps, another user had the same laser https://www.photonlexicon.com/forums...ight=EM-RGB24B

[VDX]

... hmmm ... seems to be pretty "cheap chinese crap", so no chance for 40kpps -- better try with 20kpps, if the geometry will show some consistency ...

Viktor

[buffo]

I am 33 years old and have just started breaking into the laser world

Welcome to Photon Lexicon! You have come to the right place. I noticed that you haven't entered a location on your profile. Please consider doing this, as we have members scattered all over the place and if someone is near enough to you they may be able to meet with you in person to offer assistance.

Can you push a laser too much with complex animations, more drawing more points, etc?

Yes. Most definitely, yes. If you push the scanners too hard, they will overheat and eventually die. The scanned image will look terrible, and sometimes you can hear the scanners start to whine, or worse, to make a screeching sound. If you hear this, stop the output! Driving the scanners into resonance can destroy them.

Normally you will have plenty of notice that you're getting close to the limits of the scanners, because the image starts to look like hash. Also, most scanners that are rated for at least 30Kpps speeds have either a high-current cutoff (polyswitch) on the scanner amp or they have a thermal overload circuit. Either one will shut down the amp. In most cases this will prevent permanent damage, unless you keep tripping the circuit over and over...

cheap laser from Aliexpress, Emma Laser EM-RGB24B.

Hmmm. A quick search suggests that you probably paid less than $400 for this projector, and it is rated for 1.5 watts of output. That's most definitely a "cheap" projector. Based on the pictures I saw, it looks like the scanners in this projector might be capable of 15Kpps speed AT BEST, and might only manage 10K or 12K. If you were running Modulaser at the default of 30Kpps, you absolutely were pushing the scanners way too fast.

Fortunately, as long as you didn't leave it running like that for too long, it's possible that the scanners are still OK. Try reducing the scan speed to 10Kpps and the image size to 20% and see how they look. (Note: the image will flicker more at the lower scan speed - this is normal.) See if the test patterns look better at the slower speed and angle. If so, then you've found the problem - just keep the speed lower and you'll be OK.

Keep in mind that your maximum safe scan speed is also limited by how wide your scan field is. If you have the image size at 100%, your maximum speed limit will be lower. If you reduce the size to 20%, you may discover that you can bump the speed up a few K. (Which is why I suggested you start at 20%.)

some of the designs seemed to push the laser galvos harder than others (whining noises).

Abstract patterns (so-called "lissajous" or spirograph-like images) can be very complex. It is easy to exceed the capabilities of even a good set of 30Kpps scanners when displaying a complicated abstract. The whining noise you heard is probably not a good sign. True, most abstract patterns will generate at least a little whine - even on 30Kpps scanners - but it should be a soft, subtle tone. If you noticed the whining as soon as you started displaying the image, and especially if it was loud, then yeah, you were over-driving the scanners. (Try not to do that...)

it no longer will draw simple objects correctly, such as a circle

Describe what the image looks like when you tell the projector to draw a circle... (Got pictures?) And does the circle look any better if you reduce the scan angle?

I have reached out to their tech support but I fear the worse when dealing with a foreign laser manufacturer (I get what I pay for).

Sadly, yes. If you have toasted the scanners, they will need to be replaced. I suspect you won't get very far with customer support on AliExpress. Fortunately, if it comes to that, you can probably install new scanners yourself (assuming you're not afraid to do a little re-wiring inside, that is). This might also be a good time to upgrade to a set of scanners that can handle true 30Kpps speeds. For around $250 or so you can install a set of scanners that will work *much* better.

I was reading the post on tuning galvos, but not sure if this is the issue.

That might be my scanner tuning tutorial... Re-tuning may help if the scanners overheated and something changed internally. When scanners overheat, the magnets can lose strength and the bearing/shaft clearances can change, to name just a few concerns. Provided these changes aren't so bad as to make the scanner useless, a re-tune can sometimes compensate for them. However, I would rate that as a last resort option.

Normally people re-tune scanners to correct a bad tune from the factory or to correct for scanner drift due to normal wear and tear. Less often they re-tune because they changed one of the mirrors and the rotor mass is now different. But trying to re-tune to correct a mechanical failure is not going to be very effective.

Also, I did test using ILDA interface as well as simple animations from .ild filed on the SD card and both had the same issues.

This is starting to sound more and more like you wiped the scanners. But we need more information to be certain. It would be best if you could test the projector at a known scan angle and known scan speed.

I'd like to see a picture of what the laser media test pattern looks like at 8 degrees and 10Kpps, if you can do that. (8 degrees means that the image size should be 14 cm tall and 14 cm wide if the projector aperture is 1 meter from the wall.) If that looks OK, then try it at 12K, and then 15K. (same angle)

If you can't do the laser media test pattern at 10K and 8 degrees, something is definitely broken...

Adam

[jdavis7765]

Welcome to Photon Lexicon! You have come to the right place. I noticed that you haven't entered a location on your profile. Please consider doing this, as we have members scattered all over the place and if someone is near enough to you they may be able to meet with you in person to offer assistance.



Yes. Most definitely, yes. If you push the scanners too hard, they will overheat and eventually die. The scanned image will look terrible, and sometimes you can hear the scanners start to whine, or worse, to make a screeching sound. If you hear this, stop the output! Driving the scanners into resonance can destroy them.

Normally you will have plenty of notice that you're getting close to the limits of the scanners, because the image starts to look like hash. Also, most scanners that are rated for at least 30Kpps speeds have either a high-current cutoff (polyswitch) on the scanner amp or they have a thermal overload circuit. Either one will shut down the amp. In most cases this will prevent permanent damage, unless you keep tripping the circuit over and over...



Hmmm. A quick search suggests that you probably paid less than $400 for this projector, and it is rated for 1.5 watts of output. That's most definitely a "cheap" projector. Based on the pictures I saw, it looks like the scanners in this projector might be capable of 15Kpps speed AT BEST, and might only manage 10K or 12K. If you were running Modulaser at the default of 30Kpps, you absolutely were pushing the scanners way too fast.

Fortunately, as long as you didn't leave it running like that for too long, it's possible that the scanners are still OK. Try reducing the scan speed to 10Kpps and the image size to 20% and see how they look. (Note: the image will flicker more at the lower scan speed - this is normal.) See if the test patterns look better at the slower speed and angle. If so, then you've found the problem - just keep the speed lower and you'll be OK.

Keep in mind that your maximum safe scan speed is also limited by how wide your scan field is. If you have the image size at 100%, your maximum speed limit will be lower. If you reduce the size to 20%, you may discover that you can bump the speed up a few K. (Which is why I suggested you start at 20%.)



Abstract patterns (so-called "lissajous" or spirograph-like images) can be very complex. It is easy to exceed the capabilities of even a good set of 30Kpps scanners when displaying a complicated abstract. The whining noise you heard is probably not a good sign. True, most abstract patterns will generate at least a little whine - even on 30Kpps scanners - but it should be a soft, subtle tone. If you noticed the whining as soon as you started displaying the image, and especially if it was loud, then yeah, you were over-driving the scanners. (Try not to do that...)



Describe what the image looks like when you tell the projector to draw a circle... (Got pictures?) And does the circle look any better if you reduce the scan angle?



Sadly, yes. If you have toasted the scanners, they will need to be replaced. I suspect you won't get very far with customer support on AliExpress. Fortunately, if it comes to that, you can probably install new scanners yourself (assuming you're not afraid to do a little re-wiring inside, that is). This might also be a good time to upgrade to a set of scanners that can handle true 30Kpps speeds. For around $250 or so you can install a set of scanners that will work *much* better.



That might be my scanner tuning tutorial... Re-tuning may help if the scanners overheated and something changed internally. When scanners overheat, the magnets can lose strength and the bearing/shaft clearances can change, to name just a few concerns. Provided these changes aren't so bad as to make the scanner useless, a re-tune can sometimes compensate for them. However, I would rate that as a last resort option.

Normally people re-tune scanners to correct a bad tune from the factory or to correct for scanner drift due to normal wear and tear. Less often they re-tune because they changed one of the mirrors and the rotor mass is now different. But trying to re-tune to correct a mechanical failure is not going to be very effective.



This is starting to sound more and more like you wiped the scanners. But we need more information to be certain. It would be best if you could test the projector at a known scan angle and known scan speed.

I'd like to see a picture of what the laser media test pattern looks like at 8 degrees and 10Kpps, if you can do that. (8 degrees means that the image size should be 14 cm tall and 14 cm wide if the projector aperture is 1 meter from the wall.) If that looks OK, then try it at 12K, and then 15K. (same angle)

If you can't do the laser media test pattern at 10K and 8 degrees, something is definitely broken...

Adam

Wow, a weath of information you provided me! Thanks. Profile has been updated with location and some hobbies!

So I certainly heard some high pitched whining noises and my better instincts did not kick in to ask before pushing it further and further unfortunantely.

So to display a test patten, I could do this either from an .ild and choose the scanning speed in the software of the laser and report back after that. I will probably get to it tomorrow. Been going back with their support and do not have high hopes :shrug: but will see where it goes.

I am happy to know that I could potentially make repairs on my own and am certainly up for getting my hands dirty so long as there is a path to follow.

Again, thanks for the help and I hope to continue this expensive hobby that I have broken in to. I just love the vibrancy of laser color, I have quite the obsession with LEDs as well lol.

[jdavis7765]

Okay, I decided to break it out for testing. Tested 1 meter from wall with the size of the image at 14cm on the wall, first with 12k which seemed okay, then moved to where I started seeing issues at 20k. Not sure where this leaves me but I did have a question. With the change of the scanning angle, as it gets wider, does this push the laser harder when compared to keeping a lower angle and moving the laser farther away from the projection wall?

Anway, here are the images below labeled according to scan speed.