7 questions on laser scanner design (DIY?)

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03-10-2026, 02:08
withlasers

7 questions on laser scanner design (DIY?)

Hello fellow moths, I'm a Mechatronics student doing my internship and part of my system involves a laser vector projector, the application is actually industrial, but need not be super accurate, it's just a concept for guiding the staff around. So between the expensive precise industrial laser projectors, the expensive high power laser engravers, and the expensive proprietary laserist projectors, I'm not sure what's the best use of my money, so I need your help to answer some questions, if you don't mind:

1 do you think an off-the-shelf ILDA laser projector would be reliable enough to handle just a handful of ASCII characters (~20cm tall) and 1-3 rectangles at 4m away up to +-30deg? If so, what's the cheapest option you would recommend? I only need green (420-432nm), 1-5mw output (little, I know), no z needed. I know it's really not a lot to ask in terms of kkps, but I worry about drifting (one frame slowly drifting one way with the galvo's repetitive movement), shaking (image just not being stable, as it's very noticeable being projected on a flat surface instead of on the sky), and repeatability (if image one draws a square at top left limit, image two then also does that, they both should end up kinda in the same spot, I can tolerate +-2.5mm on this).

2 do you know any open source library that I can use to optimize the .ild file? From what I read it seems converting a vector image to .ild is the easy part, optimizing the .ild is the real hard part, which proprietary DAC software usually handles, is that right? My images would be automatically generated, so those VJ/mapping fancy programs are not useful for me, as I need it free and able to automate, so in essence I don't even need a UI tbh

3 Also any open source DAC's you would recommend? I can get a pcb done for cheap at uni, but I struggle with PCB design, so an open source diagram would be greatly appreciated. If not, a cheap one is welcome.

4 For single color, x-y movement, I only need 3 channels, right? One for X, one for Y, and another to modulate the laser? Does it get modulated by pulse width (turn off, turn on) or since it's analog it just varies the voltage?

5 About the laser, I must stay within the 1-5mw range, so I will probably source that separately regardless of what the full-build looks like, and I have a question about the modulation: can I plug a CW (continuous wave) laser and modulate it, or must I find a pulsed laser diode? If it's the first, is there a way to know how fast I can turn a specific diode on and off?

6 For anyone experienced with current galvo's market: The classics I read about online are either gone, or +400eur for used ones or more for modernized models, I also see enclosed galvo heads for powerful laser applications (co2, sla, engraving,etc ) going for 120-300 eur on aliexpress, and open galvo heads starting at 70eur that seems to replicate the classics dt-30's and 40's design, what can I expect from those in terms of performance?

7 Additionally, I should procure: an IR filter to ensure no invisible radiation, safety glasses appropriate to wavelength, f-theta lens to reduce distortion at higher angles, anything else I might need? no need for an UV filter? is the f-theta lens really necessary or compensating with software should do enough for this 'slow' application?
04-29-2026, 05:17
withlasers

yep, pretty much

Quote:

Originally Posted by TheHermit

Something like this?
DJ Laser Light with App Control, 3D Animation Laser Projector for Party, Supports Custom Drawings, Text Playback,

Although by now I'm already waist deep with a pair of chinese galvos (allegedly 30k), a custom made laser module, and an ildawaveX16 DAC.
But I'm struggling to set the scan angle, I have no clue where to do it, if it's by tuning the DAC firmware (force it to map the xy positions to a lower limit), if it's by tuning the .ild file directly (hope not), or if it's by tuning the potmeters on the galvo boards.
04-29-2026, 10:06
mixedgas

I'm the remaining guy on the forum who digs deep into galvo amps and interfacing.
I'm at work but since your working in an ILDA framework with what you can buy, I'll post some files.

I'll get back to you after a day of Co2 Galvo marker reverse engineering.

I suspect your fun task will be converting dxf to .ild (Cad file to ILDA)

There should be three pdf files here:

ILDA STANDARDS

Those are the old ones relevant to galvo interfacing including a few small schematics for positioning voltage to scan amp differential interface per the ILDA electrical convention.

Download a copy of LasershowGen (Free version) to talk to your existing styles of freeware hardware/play with

LaserShowGen – Bitlasers

see for the best:

ScannerMAX - High Performance galvanometer mirror scanners

Laser Galvanometers | Novanta Precision Manufacturing

If you have to go cheap, you Want Dragon Tiger DT30s with the new self protecting scanner amp.

Certified 5 mW safe green lasers come from Z-bolt, find their OEM module page. If I were you, I'd consider a unit with TTL modulation.

OEM Laser Modules – Z-BOLT® Electro-Optics

Next , Where are you located?

Steve
05-05-2026, 06:38
buffo

Quote:

Originally Posted by withlasers

I'm a Mechatronics student doing my internship

Welcome to PhotonLexicon! Where are you located? My oldest son is currently working on an Electrical Engineering / Mechatronics degree with ECPI.

Quote:

1 do you think an off-the-shelf ILDA laser projector would be reliable enough to handle just a handful of ASCII characters (~20cm tall) and 1-3 rectangles at 4m away up to +-30deg?

Yes, although you might see some flicker at that 30 degree scan angle if you have lots of characters. But just about ANY projector using standard 30Kpps scanners will be able to project ~10 letters with a box around the whole word, assuming you are using a single-line font. As you add more letters (or more boxes), the image will start to flicker more.

Quote:

If so, what's the cheapest option you would recommend?

The Amazon listing that the Hermit posted above is probably your cheapest option. You could build something yourself, which would be a great learning experience, but it's going to cost you more. You won't need to worry about the image drifting or shaking; modern laser galvos (scanners) are closed-loop devices with accurate position detection and feedback. They are very repeatable, so long as they are tuned correctly and you don't over-drive them. You will need more than 1-5 milliwatts though, unless you're going to be using this in a dark environment. Well, 5 mw of green might *just* be visible, but it will be hard to see even under normal room lighting. (Unless this is just a proof of concept - in that case you can always add more power to the production unit.)

Quote:

2 do you know any open source library that I can use to optimize the .ild file? From what I read it seems converting a vector image to .ild is the easy part, optimizing the .ild is the real hard part

You're solving the traveling salesman problem, which is an NP-complete problem. So, yeah, it's not trivial. Dunno if there are any libraries to help with that or not...

Quote:

3 Also any open source DAC's you would recommend?

There are a few, but have you considered using a modified sound card as your DAC? There are a few open-source projects for this, and usb sound cards are really cheap. You still have to add the differential amp, and you need to bypass the DC-blocking caps, but it's a fairly straightforward mod... There are several threads here on the forum talking about this sort of project.

Quote:

4 For single color, x-y movement, I only need 3 channels, right? One for X, one for Y, and another to modulate the laser? Does it get modulated by pulse width (turn off, turn on) or since it's analog it just varies the voltage?

Correct. Well, technically X and Y are sent as differential signals, so you have X+ and X-, then Y+ and Y-, but you can come out of the DAC with a single-ended signal and then feed that to a differential output amp to get the correct signal levels. And yes, your modulation is a single-ended signal (0-5volts). The ILDA standard uses the INTENSITY signal for monochrome projectors, but often you'll find that manufacturers just hook up the green color signal (if the output is green-only), or the red color signal if the output is red only. The type of modulation depends on the driver. The ILDA standard supports TTL color (0 = off, 5 Volts = on), but it also supports analog color modulation, were the voltage can be anywhere from 0-5 volts, giving you the ability to "dim" the laser. (Side note: Most DACs use 8-bit resolution for the color signals.) Finally, you can also use pulse-width modulation to control the color, assuming the laser driver can modulate fast enough. Bottom line though, analog modulation is pretty much standard these days.

Quote:

5 About the laser, I must stay within the 1-5mw range, so I will probably source that separately regardless of what the full-build looks like, and I have a question about the modulation: can I plug a CW (continuous wave) laser and modulate it

Assuming we're talking about a laser diode, then yes, you can modulate it, provided you have an appropriate laser diode driver circuit. A laser diode driver is a constant current device. (See Sam's Laser FAQ for more info.) But assuming you have a good driver, you can do analog modulation, or TTL, or PWM. The laser diode doesn't care, so long as you don't exceed it's ratings. (And yes, the datasheet for the diode should include information about maximum frequency for PWM, but that's mostly to do with RELIABLY turning it on, rather than causing damage. Peak current is the real killer of laser diodes.)

Also, I'm assuming you are worried about staying under 5 mw due to regulatory concerns? If so, there could be ways around that limit, particularly if this just a demonstration build and not a completed product for sale. Is this project for the school, or for your internship company?

Quote:

6 For anyone experienced with current galvo's market: The classics I read about online are either gone, or +400eur for used ones or more for modernized models

OptLaser in China sells DT-40 scanners for around $225 or so, and they're very good scanners for the price. I can't speak to the stuff you find on AliExpress.

Quote:

7 Additionally, I should procure: an IR filter to ensure no invisible radiation

Unless you are using a DPSS laser, there won't be any IR anywhere in the device. Even if you did use a DPSS green laser, it should have an IR filter built-in.

Adam
05-26-2026, 03:42
withlasers

Quote:

They are precisely tuned

: is there a guide on how to safely tune them, then? I just got everything working again, and was about to tune them as per Zenodilodon's video from last week.
I am asking but will be searching it for it too, as when displaying a circle I hear knocking and 2 sides of the circle are clipped flat, meaning its hitting a limit, so I guess I am looking for some centering/offset setting.

Quote:

common with most ESPxx MCUs

: I just checked the amplitude of the wave on the scope and it's xxx, from what you wrote I understand 5v will work, but since the ILDA standard expects +-10v I will be limited to half of the angle for this galvo+amp kit anyway, right? I've seen conflicting info regarding the amplitude of the signal (dac->driver board) saying both 10v and 20v for amplitude...

Quote:

But, if the ildawavex16 DAC's firmware is open source, that might be your best option. Perhaps the firmware is intentionally shipped with reduced gains to avoid hobbyists over driving their galvos. Stanley Projects should be able to advise.

: yep, as a matter of fact he just released a new firmware last week that's much better than the previous barebones one, perks of living in an AI I guess, btw he updated it as he released a new version of the ildaWaveX16, now with a raspberry Pi MCU for all the network/file reading/whatnot leaving the esp32 dedicated for buffering and timing of the output signal, it's looking really cool from what I have seen, and yea he's pretty helpful on his discord channel. You guys should check it out he made a youtube video on the the new release.

Quote:

Most laser imaging apps provide setup options for kpps, RGB balance, and image optimization. Otherwise, those functions need to be coded within the MCU's firmware.

: I see, well maybe I pull a free one from the interwebs to test some images, but my usage will be all automated so I don't think I will be using imaging apps unless they got a free API.

Quote:

What are you using to generate your imagery?

: Right now: nothing. I am still building the software, but I have my eyes on a library that allegedly can do dxf to ild, not sure how good it is with all the timings, cornering and blanking... if there are any free suggestions I'd love to see it
05-26-2026, 04:40
withlasers

Quote:

I suspect your fun task will be converting dxf to .ild (Cad file to ILDA)

: ngl I'm banking on openlase or any of the forks on github

Quote:

Next , Where are you located?

: Eindhoven, the Netherlands.
05-26-2026, 05:06
withlasers

Quote:

Welcome to PhotonLexicon! Where are you located? My oldest son is currently working on an Electrical Engineering / Mechatronics degree with ECPI.

: I'm in Eindhoven, south of the Netherlands

Quote:

Well, 5 mw of green might *just* be visible, but it will be hard to see even under normal room lighting. (Unless this is just a proof of concept - in that case you can always add more power to the production unit.)

: I ended up getting a 20mW 520nm, hoping that I can drive it at 5mw and still be readable, don't want to go higher because it's meant to be used in manufacturing and it would be a hassle as per IEC 60825

Quote:

have you considered using a modified sound card as your DAC?

: yes but since it's an internship project I've been trying to keep things simple and documented... maybe for a personal project after this!

Quote:

The type of modulation depends on the driver.

well guess who made the driver? I won't expect much from it haha I spent almost a whole month struggling to get the board to work, using an lm317 for current ceiling, a series of transistors and a 2 channel opamp for the photodiode feedback (I wanted APC because I want to drive the laser at max power permissible by law hehe and without APC based on the pd feedback it darkens as temp rises and then it might be too dim to view, since it's moving fast on the surface) but that failed and now I switched to a barebone board with an lm317 hard set at 60mA, a mosfet and some protection diodes/cap, not proud of it but at least it works, but it seems the DAC is the bottleneck right now, the "always on" is blinking I assume it's an optimization issue while cycling through the internal routines of the MCU

Quote:

Also, I'm assuming you are worried about staying under 5 mw due to regulatory concerns? If so, there could be ways around that limit, particularly if this just a demonstration build and not a completed product for sale. Is this project for the school, or for your internship company?

: yes from what I recall of the IEC 60825 the limits are based on power (energy/time) in such a way that PWM does nothing to safety, in fact below the blink response time it the regulations get tighter, as we can't blink when it happens, so at the end of the day it's the power reaching the surface divided by the area of the dot that's key for the regulation. Our internships are 'professional' here, so I'm working for a company with an intern contract, and then school will grade me based on it, then 6 months specialization, then a final internship for graduation and I'm out

Quote:

Unless you are using a DPSS laser, there won't be any IR anywhere in the device. Even if you did use a DPSS green laser, it should have an IR filter built-in.

: bet, I got a direct diode after reading up on dpss ones, thanks for the advice!
05-26-2026, 05:11
withlasers

Quote:

Originally Posted by TheHermit

Zenodilodon just posted this great video covering galvo troubleshooting & tuning.

https://www.youtube.com/watch?v=vvDk-o-D0w0

excellent recommendation, although as I said in my previous comment I'm not sure if I should give it a go at the pots just yet, atm I'm trying to figure out where in the pipeline I should tune what.
Like per example, where to store and correct for the surface angle?
What exactly should be tuned at the hardware level (trimpots)?
What should be tuned at the (DAC) firmware level?
What is normally configured at the .ild file level?
05-26-2026, 23:26
withlasers

Quote:

Originally Posted by TheHermit

What does xxx mean?

: means I got carried away before I could scope the exact peak to peak amplitude of my signal, but I just did and it's 9.92v

Quote:

Originally Posted by TheHermit

Yes, your galvos will complain with a 'clicking' sound, while clipping and you should see it on your scope..

wait, what do you mean I should see it on the scope? shouldn't the signal DAC ---> DriverBoard remain a perfect sine wave (for a circle) regardless of what's going on downstream in the control loop between DriverBoard <===> Galvo?

Quote:

Originally Posted by TheHermit

For clarification, most ESP's GPIOs output 0-5v. So there would be a 2.5V offset.

: Indeed, the ildawavex16 takes care of stepping it up "The analog output stage consists of a DAC80508, which is an 8-channel, 16-bit SPI DAC with a precision internal reference, used in gain-2 mode, producing a 0-5V output, which is then processed through a 2-stage operational amplifier circuitry to generate ILDA-compliant voltages."
What I meant that makes me confused is how some people say +-10Vdc to mean a 10v differential peak-to-peak, while others say +-10Vdc to mean a 20v differential peak-to-peak, but I'm fairly certain at the moment that the ILDA standard for the signal out of the DAC towards the driver board should range from -5Vdc to +5Vdc, regardless of how it might be written.

Quote:

Originally Posted by TheHermit

Cloudlase is free, but don't have any experience with it and like most 'free' software it needs an ILDA DAC (EtherDream) that will set you back a few hundred $.

: thanks for the suggestion, I downloaded lasershowgen as instructed and will see if I can make it dance with the ildawave, and then check Cloudlase.

Quote:

Originally Posted by TheHermit

Don't you have a deadline looming on your science project?

: yes sir, got till 9th of June for the uni's report, and then 10th of July for the work contract to expire, just yesterday I finally got the galvos-laser-laserdriver-DAC all working (together) for the first time, now I need to fine-tune without breaking anything, and then implement this operation into my application.

So after having scoped the signal from DAC to Driver Board, I see the signal isn't that pretty, but it's solid and symmetric across the zero, which means it's asking it go to the right by the same amount as it's asking it to go to the left, at this point I think this is happening as a combination of 2 things:
1. the circle being full size (it's a test circle built in to the firmware)
2. the galvo being just a little off to the right and down
So I'm thinking I will change the firmware to include a scaling operation by any values 0<v<1, set it to 0.9, and enjoy a clean canvas without having to worry about the little offset at the center, because if the signal is clean, and the galvo is hitting the corner, it must mean that I should find the right potmeter and adjust it, correct? Unless I'm mistaken about the system, which very well could be as the firmware also offers a cross and a square, both are full size, and neither is getting clipped, which is strange, almost as if only the circle is "out of bounds".
Guess I will load up a different circle, see how the wave looks and how it behaves when within bounds, before downscaling in the firmware.
05-26-2026, 23:57
withlasers

It appears that it is indeed a hardware induced bias, because even after flipping X and Y axes (which for center-symmetric shapes shouldn't do anything signal-wise), the bias remains over limits on the right and bottom
05-28-2026, 01:03
withlasers

Many thanks, mate.
Much clearer now what the signal limits should be, for now I will limit the firmware to never request more than 9.5 volts differential from the DAC, in X and Y, this global downscale will keep me out of the edges without messing with the center/offset.
I already did and it worked yesterday, actually, but I copied the implementation from a brightness setting that existed on the config webpage, and that was kinda broken, so my setting was also broken.
So from yesterday to today I'm rebuilding the firmware with various fixes and new stuff.
I gotta say if his plan was to get rich, then he should look for a better plan ;), this isn't exactly a "disruptive" market where you can design a simple product and become rich just like that.. but maybe you know him better than I do
Anyway, I'm finishing up my firmware soon with basic features just enough to enable a testing workflow (load ilda test pattern) and then I will move back to my application, thanks for the tip on focusing on the end goal, in between all the other ways to project an image, the different purpose galvo sets, the protocols, the laser knowledge, the electronics and pcb making for the laser, the lens knowledge, the system design of the whole projector, the data manipulation from CAD assembly to individual parts .dxf's, this project has me all over the place, it's easy to lose track hehe but this is the final stretch, I honestly think the only challenge ahead is the dxf to ild conversion, which I'm banking on openlase forks to help me with, after all I will only be projecting the outlines of the parts and some alphanumeric codes next to it....
So yea, wish me luck! and thanks for all the support, and cool jethro pic! it took me a few times opening this page to put a name to the face but I knew that I knew it from somewhere!
05-28-2026, 02:24
withlasers

Quote:

Originally Posted by TheHermit

Nah. I've only watched some of his earlier YT videos, trying to use steppers, instead of galvos.

: to be honest I have been thinking about pushing steppers to the limit for a summer project, I'm wondering how interesting the workflow could become if switched to digital, will be slower, sure, but it might allow a different way of drawing paths, directly with vectors instead of "timed points", just because it's cheap to try and I'm curious with it. Also analog control loops breaks my brains, left and right..

Quote:

Originally Posted by TheHermit

Sounds like you're making good progress.

: yea, once I'm done I'll check with the company if they let me share parts of the report here for your curiosity but also for future noobs reference. I took too much from this forum not too contribute hehe.

By the way, question about the sounds, I got rid of the clipping by the global downscaling the X-Y coords at the end of the pipeline, right before the DAC's, but the circle is still making a noise, less, but still making clicking noises, I looked into his code and I'm assuming it has to be with how he generates the points for the circle vs for the square/cross/heart, I'm assuming the circle has a crazy high point resolution and that's causing the audible noise, even at lower scales.
However when loading more complex frames, like test patterns, it gets a little noisy too, from soft coil whirring up to audible ticks and clicks, not as bad the test circle from ildawavev2 firmware, but still noisy. And now I'm left wondering: what level/type of noise is considered acceptable? and at what point should I get concerned with the lifespan of the galvo's/driver board? Because when I do a simple square from the firmware, or a circle.ild from the library here, I hear 0 sounds coming from it, but then again those are very simple shapes with smooth acceleration curves... I just don't know what to expected from the complex frames...

Quote:

Originally Posted by TheHermit

Jethro Tull was the band. Aqualung was the 'poor old salt' on the album cover, looking alot like TheHermit

: oh I know, I was lucky enough to catch Ian Anderson in a swampy tent concert during a week-long music festival in the south of Brazil, a bit over a decade ago, those were some magic flute solos! And you mean it looks like yourself? Or like the hermit archetype in esoteric practices like tarot?
05-28-2026, 23:02
withlasers

Quote:

Originally Posted by TheHermit

"timed points", as in **kpps?

yes, I meant I was wondering what if instead of spitting out two points " : " at a set period, with the caveat that we don't turn off the laser in between them, and get a line, what if we could spit out a vector " l " that has its own duration for travel? sure it's not interesting with lines, but I wonder what the workflow would look like for splines, anyway, just a cheap experiment to run.

Quote:

Originally Posted by TheHermit

What does his sine wave look like at the X/Y output connector on the scope?

So the weird one I mentioned before was this:
https://drive.google.com/file/d/1nhZ...usp=drive_link
But I'm at this:
https://drive.google.com/file/d/1mRk...usp=drive_link
https://drive.google.com/file/d/1D7Y...usp=drive_link

I was busy trying to reduce the breaks between the end of a frame and the start of the next one, but it seems that this is the most I can shrink it.
Now, even at 10kpps and a moderate angle (0.7*30deg), I hear something, I wouldn't call it a click, more like a tick, a quick tap, if I lower the angle absurdly (0.1) I only hear the high frequency whirring that I would expected anything to do at this speed, unless in a vacuum hehehe. so I assume that's normal sounding, but not sure if healthy.
But then if I load the 12k ilda pattern, it's ticking like crazy, which I'm not sure if safe or not, and that's at 10k which makes the image barely readable, just strong dwell points with light lines in between them...

Quote:

Originally Posted by TheHermit

Shouldn't have clicking noises with a sine wave.

I thought the clicking was from the end of a circle frame to the start of the next, and tried to reduce that, it improved a little but not much, I guess I would need to have a constant sine+cos to get the cleanest sounding circle, but then we're not talking about an ild file being interpreted and passing thru a DAC anymore, right? then we're talking about a signal generator.. because of the blanked points at the start and end of a file/frame...

Quote:

Originally Posted by TheHermit

Is it clean or still have overflow inversions going on? If it's only a test circle for deflection/size measurements, then it doesn't make much sense to be high frequency.

In fact I don't think I ever got the inversion you're talking about specifically, just that distortion shown above, but maybe the audible noise is coming from the steps along each point, if you look closely you will see that the step response of each point along the circle shape is very fast and ripples around... atm I'm thinking that's where most of my clicking is coming from.

Quote:

Originally Posted by TheHermit

It's important to have the driver boards' power amps properly in contact with heatsinking usually screwed into the aluminum optical plate w/paste. They can get pretty hot, if being driven hard with pulse, square, sawtooth, or even ild frames with long leaps. The galvo's X/Y block is also a heat sink.

yep that's how this kit is made, you described it exactly, I'm happy that they insulated/heatsunk the tab properly, and then I bolted the heatsinks to the frame (3mm stainless steel sheet bent into a cube) but it is getting hot, I measured 43deg yesterday, so I will most definitely be installing a fan, when I'm done I think I will even interface the heatsink to the frame, either with pads or paste...

Quote:

Originally Posted by TheHermit

In terms of noises, you can tell by the image shape whenever the galvos are being driven to hard. Whenever sharp corners start rounding off, lower the frequency and/or image size.

I got this with the LMTESTF.ild (diamond inside square that became famous for coming in standard on a piece of hardware/software, you definitely know it) at 30k, the diagonals became ellipses, but at that point it sounds almost like my ultrasonic toothbrush lol do you mean with this phrase that if the image shape is pristine, the noises can be ignored as normal operating noise? If so then there's my threshold to feel safe playing with it. I really gotta move on to building a mapping() function so the plane transforms can happen to my drawings before they are converted from .dxf to .ild, but I don't feel safe with it just yet.

Quote:

Originally Posted by TheHermit

Yes. I had never heard R&R flute, like Ian's. Inspired me to buy a silver flute and ave a go. In '79, I was doing Laserium shows at the London Planetarium and was fortunate to see Tull at the Hammersmith Odeon, during their peak. Such an amazing showman.

Yes, when my hair is long and yes, but without the hooded cloak.
😎

damn you are living the dream ain't ya? hahaha let me know if you know other bands like that, because I find it hard to relate jethro's sound to anything else out there

I also pushed a video to google drive so I can share the noises it makes, unfortunately it seems the upload button here is broken...

https://drive.google.com/file/d/11nb...usp=drive_link
05-29-2026, 05:02
withlasers

Quote:

Originally Posted by TheHermit

#1: Nasty waveforms, as if it's only noise or the scope's ground isn't connected to the project's ground. Is the project actually grounded (aka Earthed, in EU speak)?

I just figured out what was the problem with those ugly waves, it's the generated circle from the firmware, if I load the circle.ild I get the long pauses, and if I load the circle from the firmware I get those ugly waves, I've seen the code and I think it's because it's generating points on a 90deg arc and multiplying coords according to the quadrant they are, was something overcomplicated like that, anyway not a problem, I won't be dealing with that.

Quote:

Originally Posted by TheHermit

#2: Don't understand what those spikes are about.

those are the V+ and V- of the X axis making a circle, and as you can see there is a looong time in between them... I thought I reduced all the firmware delays before and after frames/files, but now that you said it should be a constant wave, I might look into the firmware again.. those are being read from the sd card, let me try and stream points over wi-fi see if the delays are different then.

Quote:

Originally Posted by TheHermit

#3: Much cleaner wave, but why only one, instead of a stream?

it's the same wave as before, just zoomed in, like I said I improved the firmware to reduce the time between files, but I got to a point where the time before and after each wave match the blank points at start and end of the circle.ild that I have. I am about to do the math to see if the resolution of the DACs match what I'm getting here, maybe I have a firmware bug shrinking my actual DAC resolution...

Quote:

Originally Posted by TheHermit

Is that what those lumps at both ends of the wave are? Points on top of each other?

nevermind what I said in grey, you're right, even if they were blank points at the start and end of circle.ild, they would have positions, unless that's their position, but nah it doesn't make sense that circle.ild would have more time blanking than lasing.. I will double check the .ild see where are the blanks supposed to be.

Quote:

Originally Posted by TheHermit

Diodes are far faster than the galvos. If there's blanking between points, often there will be several points at the same position, with pre and post blanking settings within the imaging app to hide overshooting and bright corners. Otherwise, that needs to happen manually while plotting the ILD frame(s).

Ok, that's going to be for v2 of this prototype hahaha no way I can fiddle with those optimizations in the short time I have, but I would love to, like I said I don't have an imaging app, I'm getting step assemblies, flattening to .dxf's where each part in the assembly is in a separate layer, and upon request to the application, it will gather a group of layers (parts), transform to the geometry stored (projector at the ceiling, assembly table has wheels and likely move during a shift or day), then convert to ild using one of the forks from openlase on github, hopefully my single-frame .ild files with nothing but a few letter and rectangles (I might even program round corners if I have the chance) should be easy enough on the hardware..

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I don't think so. Those steps are too small to generate much sound which would be more of an hf tone, instead of clicking. Noticed the stair stepping on all 3 videos, as if X & Y outputs are alternating in time, inside a loop that has a millis() delay in between to control kpps, instead of spitting out both X & Y together, followed by a single delay before the end of the loop.

I see, it makes sense, still I will check if those steps are a product of the DAC limits or if there's some bad math somewhere limiting their true potential, I have to double check because it could be that I downscaled the projection so much when I took the picture, that the DAC resolution was showing.. I don't know about that second part, I haven't scoped both X and Y simultaneously yet, so all you've seen is one single axis.

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Yes, fan(s) definitely. Fully enclosed case to keep the optics dust free. Thin AR coated glass emission window. Filtered air inlet at one end + ~4020mm fan near the galvo drivers on the opposite side of the case should be sufficient.
Your 5mw diode won't generate much heat, but still needs to be mounted inside a surrounding heat sink block. Whenever laser diodes get too hot, their resistance will drop, sending them into self destructive thermal runaway.

oof, guess I'll have to jerry-rig a fan on the lid of this thing, unfortunately I got to designing the box after shit had hit the fan already, and did it with loads of mistakes like this, I'll make a note for v2 to keep optics enclosed, and electronics exposed to airflow!

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Yes, generally speaking, as long as the galvos are tracking accurately, then all swell unless you're throwing a high level >2kHz sine at them. The circle will look ok, but will be small because of inertia. The drivers will be working hard and generating heat.

ok, good to know, that gives me that threshold of acceptable whirring/buzzing/ticking

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Wow! You can make galvos talk? 13 secs of a wandering camera doesn't provide much time for analysis. Couldn't hear the clicking in the video.

sorry but the interns don't their own office ;) too bad you can't hear, I can hear it in the video, let me record another video with more info

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Those galvo mirrors look very close to each other. Are you sure the clicking noise isn't the mirrors hitting each other at high signal levels?

nope, it's chinese but not that chinese hehe

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I don't recognize those galvos. Ali Express no name specials, I presume? How many kpps & @ what deflection angle are they touting? If that's were they came from, then you might want to half those claims in reality.

this is the one they say 30k and 25deg, but yea I can't get a readable 12k ILDA test pattern even in a tiny angle..

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Check your firmware to try getting rid of the stepping. Then you can start working on the ILDA imagery.

Will do, like I said it might have been that I was working with a stupid small angle, like 20% of the total angle, which would mean +-1v in the signal, and maybe at that scale of 0-2 volts the DAC resolution starts to show, not sure, will find out if it was a DAC limit or firmware bug.
But I gotta say I'm only looking into the steps and the gap between these circles right now because I think that might get my ILDA 12k performance to increase, and once I'm happy with the performance I'll move forward with the project.. still a lot left to do and plenty more to write in the report ^^

I'm going to record a new video right now with some more info on my build and show what I failed to show before
06-09-2026, 23:26
withlasers

small update
Small update just to keep you guys ("guys" as in TheHermit and all his personalities) entertained:
•That day we closed up earlier and I couldn't record a proper video.
•Next week started slow on a Tuesday, but I did manage to solve:
1. The weird waveforms, was a byproduct of the Circle.ild that I had, the auto-generated circle from the firmware looked better but had its quirks as well, eventually I generated a "max" diameter circle with 1000 points and then the waveform would both: stitch smooth between each period, and have smoother steps along it.
2. Found the angle for scanning the 12k ILDA tp at 30kpps, it was 7% of max amplitude, which assuming a max of +-30deg is around 2deg, there you have it in case anyone is interested in buying that particular galvo head set.
3. Wrote a new firmware from scratch that focuses on reliability of the show, regardless of network situation/file size.
•However I also managed to:
1. Burn the laser, a zener diode and slightly damage the LM317 I'm using as current controller, all because I thought it was time to reduce the power to class 2, but wanted it adjustable, so I've put a potmeter along the set resistor, to allow me ranging the resistance between 20-40 Ohms giving me 30-60mA which is equivalent (when cool) to 1-20mW of optical output at the diode.
  Not sure what happened there, took me 1 day to get it running, and it was blinking, at the end of the day it died, took another day to figure out exactly what had died, the why is still unsure, definitely adding a potmeter in the current path was the problem, but it could be inductance from the resistance coil, could be that the pwm I introduced didn't bode well with the circuit, could be that adjusting the potmeter during operation caused the lm317 to freak out a little, due to the electromechanical design of potmeters (wiper losing contact as it turns would open and close the circuit, switching the setpoint of LM317 from 30-60mA wicked fast).
2. Burn the spare laser, decided to use wires to the leads this time, and the tin flowed down and shorted the pin to IC packaging, in my lead-smoked-brain I tried scraping it with the solder iron, which probably overheated the packaging, I realized it immediatelly and scraped the tin instead of using heat, but it was too late, multimeter says it's open with no voltage drop across :c we just ordered a new one and Monday I shall continue with testing the complete application.
So yea, all hands on deck now, I'm blasting the report faster than chatGPT, by Friday I deliver it as is and from Monday I carry on with final tests, production testing and presentations, until 10th of July.
When I get it up and running again next week I'll make sure to get a video and share with you guys my little projector, I was surprised with how well it handled some animations, it can get quite noisy at 30k even at a small angle, but luckily I don't need multiple frames anyway.
06-10-2026, 00:53
TheHermit

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Originally Posted by withlasers

Small update just to keep you guys ("guys" as in TheHermit and all his personalities)

Thanks for the update. Hadn't forgotten about your June 9 deadline. Thought you might have needed to pull an all nighter and was giving you some time to recuperate, before PMing to ask how it went.
Glad to learn that you've managed to deal with all the technical burnouts to get your projector happ'nin and still on schedule with sufficient time to program your presentation, next month. Well done!
Unfortunately, your electronics mysteries are above my skill set, as a mere old school laserist, electronics guru isn't one of my personalities.
Perhaps Adam or Steve might like to chime in with some helpful electronics suggestions.
Looking forward to seeing your video.
BR
Roj
06-11-2026, 12:13
mixedgas

Potentiometers open and close the circuit as you spin them, especially when in the tail end of a LM317.

There is a driver circuit here that might help prevent such failures:

diliev.com/home/materiali/OLUP/0470402296_Electro-OpticalA.pdf

and here:

die4laser.com/dvd-rec/Die4Drive.htm

Steve
06-18-2026, 03:48
withlasers

yep that's what I thought

My strongest guess is that the constant on-off of the potmeter is what messed up my circuit.
I got the new diode delivered, but turns out I didn't burn the #2 one while soldering, the multimeter accused open but I guess it can't handle the voltage drop of the laser diode... So now I have 2 diodes again :D
Just put everything back together now, adjusted the heatsink so the lens can thread in and out of the focal point (before it was just out of the focal point).
And I'm back to square one hehe where I was 2 weeks ago.
Built a straight dxf->ILDA converter with claude's help, now polishing some final aspects of my main program to test it and hopefully next week I'm at the factory with it, testing it in production.
Wish me luck! I'm making pictures and videos as I can and will share more as I have time, the last two nights I was up until 1am 3d printing lens seats...