image output is skewed keystone issue.

[prosnurfer]

Hey everyone! looking for some input here, I have a odd issue with the output image positioning. Ill include a picture. This is just a at home play around project I had built and had it running good at one point with the alignment of everything setup well. I recently moved across the us from east coast to oregon and mailed my self my laser. i pulled it out to play with it the other day and the odd thing is the image output is skewed like a weird keystone issue, as if you were to set up a video projector to keystone to a 45 degree wall.

im using quick show, fb3, and dt40 scanners.

I assumed the stuff got tossed around a lil in shipping so I made sure all the optics were tight and the scanner was tightened down. I can align the beam path to the scanner as it should be on the bottom mirror, I made sure the scanner mirrors were mounted tight as they should be, alignment wise it seems to be solid.

i went to reset up the projector settings and projector zone. I even tried to keystone everything with quick show which didnt help at all. basically the image is always tilted down to the right and pushed back. I am not able to do fine alignment with the color overlap or the fine tuning of the rotation and position with the soft where and dichro mounts until i figure this out.

so my question to all of you is what am i missing? would tuning the scanner drivers resolve this issue? or perhaps im missing something on my hard where side. im going to reset up the dichro mounts but need some new setscrews for the fine tuning that ill have to grab from work when i go back this week. maybe im missing something in quick show main setup, iv worked through all the menus. Let me know if ya all have any ideas.!

happy holidays and happy new years to all!

[dchammonds]

Hey everyone! looking for some input here, I have a odd issue with the output image positioning. Ill include a picture. This is just a at home play around project I had built and had it running good at one point with the alignment of everything setup well. I recently moved across the us from east coast to oregon and mailed my self my laser. i pulled it out to play with it the other day and the odd thing is the image output is skewed like a weird keystone issue, as if you were to set up a video projector to keystone to a 45 degree wall.

im using quick show, fb3, and dt40 scanners.

I assumed the stuff got tossed around a lil in shipping so I made sure all the optics were tight and the scanner was tightened down. I can align the beam path to the scanner as it should be on the bottom mirror, I made sure the scanner mirrors were mounted tight as they should be, alignment wise it seems to be solid.

i went to reset up the projector settings and projector zone. I even tried to keystone everything with quick show which didnt help at all. basically the image is always tilted down to the right and pushed back. I am not able to do fine alignment with the color overlap or the fine tuning of the rotation and position with the soft where and dichro mounts until i figure this out.

so my question to all of you is what am i missing? would tuning the scanner drivers resolve this issue? or perhaps im missing something on my hard where side. im going to reset up the dichro mounts but need some new setscrews for the fine tuning that ill have to grab from work when i go back this week. maybe im missing something in quick show main setup, iv worked through all the menus. Let me know if ya all have any ideas.!

happy holidays and happy new years to all!

I would like to see a picture of your scanners; it looks like X&Y have lost their 90 degree relationship (wild guess).

[james]

A diagonal line from bottom left to top right is a plot of x = y. This looks like you have non-linear gain on both signals. Like the more negative it is the more gain and the more positive it is, the less.

[mixedgas]

I'm seeing crosstalk resulting in Skew. Check your projector wiring for the differential pairs that drive the scanner amps being interchanged. Some where you have analog signal crosstalk. Skew in this case is Xskew= Xraw +(n)Y or Yskew = Yraw +(n)X, and results from the signals summing at some point.

You only have five wires to worry about, X, inverted X, Y, Inverted Y, and ground (usually not used) to worry about.,

X and X inverted should go to the X galvo amp, Y and Y Inverted should go to the Y galvo amp. If any two are interchanged, you get Skew.

Ilda connector pinout is:




1 and 14 should go to the X axis galvo amp, 2 and 15 should go to the Y axis galvo amp. Differential signaling is used for deflection to cancel noise in the wiring. On a good day, pin 25 should only go to the color circuits, but NOT to the center input pin on each galvo amp.

in some rare cases this can occur with power line leakage into the wiring or a power supply "sagging" under load. That takes an oscilloscope to trace, usually.

Swonce in a While the axis pins may touch in a bad cable.

Good luck,

Steve

[mixedgas]

Mr. Hermit,

I might have made that four wire Skrew-up myself, once upon a Midnight Dreary using Dupont Connectors.

Hence my "bet"

Forgot to add that sometimes the axis pins may touch in a bad cable, also resulting in Skew,

If your driving with an FB4, Skew correction is an option in the user menu, and may not just be wiring.

Mr. Hermit is right, check your controller Geometry Correction settings in both Software and Hardware.

Steve

[prosnurfer]

Hey everyone! happy new years! thanks for all the good feedback! Stuck working the last 4 nights, semiconductor industry never sleeps haha, anyways i read all of what everyone said and im going to give her another look tonight.

to all about the scanners and projector: dosent have a show card this is just a at home build I put together, its using a fb3 running quick show latest version. the signal is fed from the fb3 to 25pin connector and out to each component from there. no breakout board. pins 1and 14 and 2 and 15 are used for the scanners. and ill have to double check but i believe 25 is just going to the main ground of the projector.

the scanners were not from aliexpress, but i dont remember where i picked them up ill have to check, ran me about 300ish new. when i first had it running well they do 40kpps settings on quick show with no issues. one thing id like to note is that i belive the x axis always had to be inverted in qs and it was this way from the get go, i double checked the signal to proper driver and proper scanner connections last week when i was working on this. unplugged all connections and re plugged in made sure everything was tight.

the red laser alignment issue i have never been able to get right because i used a multimode diode and its giving me 2 beams at the scanners. i tried adjusting this with the lenses, i may be using a incorrect lenses or need a separate optic to collimate the beam

the mounts are brass mounts that use 4 screw adjustments to flex the metal for the fine aliginment. and arejust mounted to a aluminum base plate that sets the height off the main base plate. all the mounts i drilled and tapped my self with a hand drill haha so i double checked that and everything is tight. but i actually ordered new dichro mounts from otp last week when i was messing around with this and maybe ill remount or use em for a new project. (its funny bc my xmass gifts i mailed from oregon to vermont to my family took a week and a half to get there and the dichro mounts came to my house in 3 days from poland!) dono how that works usps....

im thinking there may be signal leak or cross talk like you guys mentioned, some faulty connection or also some power sag. i don't believe the pots on the drivers were effected in shipping and i havent touched them thats the last ditch effort digging in to a tuning learning project id probably order a new set of scanners before hand at that point.

so for tonight!
- first off im going to clean my optics and scanners, got some mirra wipe swabs and a vial of iso with a mirra swab tip used to clean ion detector bars, double check alignment once more, had it set pretty good last week
-pull out the fluke and check my connections and voltage signals and power supply's. hopefully its just a silly connection issue and i was being lazy with my troubleshooting after a few glasses of wine on xmass night.
ill set up my oscope if i have to.
- it might help if i make a breakout board down the road, with soldered connections, bc the wires are screwed in to a 25pin ilda connector with a screw in breakout on the back ill take some better pics and post.

Thanks again for all the ideas and help everyone! ill update with my findings! hope everyone had a good happy new years and that some of you got out to see some shows or spent it with family and friends!

cheers!
matt.

[james]

Your scanner inputs are differential. That means you should have 3 solid (verified) connections per scanner. You need the non-inverting signal from pin 1, the inverting signal from pin 14 and a reliable ground connection that is the same ground as the ground from the signal source. That's just for the x scanner. You need the pin 2, pin 15 and signal ground for the y. If you want to avoid having to flip the x axis in software, just exchange the non-inverting and the inverting signal connection for the x scanner.

Upon further examination, this appears to be a conspicuous ground issue.



.

[prosnurfer]

I'm developing my own Teensy T4.1 laser synth/DAC from scratch, using Reaper's DAW, APC40 mkii MIDI surface, TouchOSC, & dual touchscreens, instead.
IOW, I'm using modified modern music production technology to play/record/store MIDI controllable visual music onto 16 MIDI tracks along a DAW's timeline (instead of LSX, QS, or Beyond). That approach is producing beautiful unforeseen imagery, with a rich set of controls and customizable workflow, but with the caveat of producing only abstract waveform cycloids, instead of wireframe vector animations (not interested). It is both enabled and limited by a freely downloadable, Arduino compatible Audio library. In fact, in order to achieve vector animations, I would need to code that vector imaging engine from scratch... maybe someday... maybe not. But, you can already do that now.
My approach will only become cost effective after repurposing the el cheapo scraps by building:

Roger this sounds like a great project. looking forward to you sharing with everyone. i dream of a euro rack modular synth that i can run a laser with. maybe one day later in life. its a big undertaking haha!

[prosnurfer]

greetings everyone! I finally got around to the laser last night, ended up having to trouble shoot my furnace instead haha, there was carbon build up on the flame sensor for the piolet and when I got home from skiing, when I was cold it would keep power cycling. I was like gosh, I just want to be a laser guy tonight not a hvac guy!

anyways i worked on this for a bit and still have not solved the issue.
- cleaned up my dichros and mirrors. nice! they were dusty.
-checked seating of wires and connections once over.
-checked wire to amp continuity. Aha! thought i found the problem

I was getting a 400k short between 2 of the scanner amp signal pins. the problem was that i have the heatsinks from the amps mounted to the base plate and they now were connected. not sure how this happened bc I originally had it set up like this when it was properly functioning. I isolated the amps by using kapton tape on the bottom of the heatsinks and screws. not the best solution but thats all i had on my desk. a teflon screw to mount would be better.
After they were both isolated and no shorting between any pin.
-amps to galvo have good connection on all pins
-one thing to note is i have 1,2,14,and15 connected to the amps and not pin 25 at all. pin 25 I have connected to the laser driver ground. maybe this is incorrect and the scanners need a signal ground from fb3 also connected?

back to the drawing board for now. got work the next 3 nights and it totally consumes my time. last week i had half my body in a eto rf gen rack trying to find some rectifier diodes, they were in the worst place, chamber finally struck a plasma after replacing them and i felt better haha.

next week when im free i gotta check power to scanners when running and the signals the scanners are getting. im wondering if the fb3 isnt sending proper signal or maybe that ground pin 25 has something to do with this. although i never did have it connected when it was working. perhaps that faulted my scanner amps?

I double checked the 90 degree orientation of the scanners and it looks right but it almost feels like that's off causing the keystone. I don't see how it could be though, the way the mirrors are mounted to the shaft. doesn't seem like that could be bent, the mounting on the block is tight.
I think you guys are on to something about a signal problem due to the curve line on the x.

Thanks for all the help and responses!! will update next week with more findings. leaning toward amp problem, fb3 issue, maybe power supply. Ill include some pics for ya all.
Have a great first week of the new year!
cheers
matt.

[cfavreau]

Your scanner inputs are differential. That means you should have 3 solid (verified) connections per scanner. You need the non-inverting signal from pin 1, the inverting signal from pin 14 and a reliable ground connection that is the same ground as the ground from the signal source. That's just for the x scanner. You need the pin 2, pin 15 and signal ground for the y. If you want to avoid having to flip the x axis in software, just exchange the non-inverting and the inverting signal connection for the x scanner.

Upon further examination, this appears to be a conspicuous ground issue.
.

I agree with James. It is probably a grounding issue. Ground loop or voltage differential or something. Best use a star ground topology for the projector (everything connects to a single point). I might have this suggestion wrong though.

Here's a link to Pangolin's old projector wiring tech note: https://pangolinlegacy.com/resguide12.htm

It is pretty good and will do a much better job of describing how it all hooks up and how to avoid issues like this.