DIY Laser levelling using webcam and laser level

Hi John,

It looks like you are using a very old version of the software, I would just download the ready to go latest version, this has the smoothing you need for actual measurements, plus a load of other enhancements, see my previous posts.

When used as a light sensor with a laser and no optics I have testing in pitch darkness and bright light and there is no variation at all, this is because the laser saturates the sensor.

When used as a camera, i.e. focused on an object such as a screen ambient light has to be completely eliminated both front and back of the sensor, you get some shine through the pcb even. I put mine in a black box.

When used as a shadow camera without optics and the shadow generator (wire in your case) very close to the sensor you should be able to just put a very intense light source behind the wire, this will saturate the sensor which is what you want, you will need some diffusion material to even out the light source as I mentioned before.

The software automatically scales the intensity plot, assuming you can generate enough contrast between the thing you are measuring and the background.

You should be able to get very repeatable measurements down to 3um, when using as a shadow camera make sure you tick the invert box in the prefs.

Keep at it!

Joe

Hi Joe

I am using the latest software

3um = 0.00011811" (Inches)

I am going to repeat the test tonight, better light control.

Regards
John

The picture you attached to the previous post was not the latest version John, the latest version has a table of measurements taken and smoothing when taking a measurement, export to csv, etc. Maybe that photo you took was from some previous experiment?

3um = 0.00011811" (Inches) --> CORRECT

FYI, this is what the latest version looks like:
Attachment 26367

Hi Joe

I ran the tests again this time using a small LED torch as a bright light source.
This gives a very sharp high contrast graph.

Strangely the scaling changed to 119.9 pixel lines with the new light source. I repeated the test a couple of times. the results were the same.

I did not change the gap between the wire and the sensor. it must be caused by the change in light source.

I used the software measure table and recorded every step between zero using 0.05mm steps see image below.

The setup I am using moves the sensor not the wire, Important for a point light source to avoid the shadow elongating like the sun in late afternoon.

This is easy to prove moving the torch by the slightest amount changes the measurement.
I really want to find an evenly dispersed light source.

I have yet to try your smoothing settings, That will be interesting.

Edit just noticed the software has changed a bit more. I will update


Regards
John

Attachment 26368

Attachment 26369

Hi Joe
Hi All

I downloaded the next version that displays a graph of the measured points. And look how nice and linear the graph is! .05mm measurement steps on the dial indicator.

Attachment 26370

I ran it 3 times to check.

While testing I moved the light a tiny bit. I had to start again, The light source will have to be rigidly mounted on the platform or you will get errors.

Will the current software work with higher resolution cameras say 1080P? I realize there would be more number crunching for he processor.

Regards
John

Hey guys,

I have been following this thread with great interest. Really great work.

I really like they way the camera + software is used for this purpose. It smells like a commercial oppertunity in my opinion.

Anyway, Since i bought a new house i am about to move my cnc machine in about a month or two.

I think i could use a laser level device for some of the needed remodelling work so that one could pass investment committee.

I would like to use this technique for a check on my machine after transport.

Actually.. it would be the first time and method i could set up for a half decent check on my machine.



So i would like to buy a new laser device with this in mind.

I only have an 8 mm umbilical type usb HD cam atm. So a really small chip.. i guess not usable for this pupose.

Maybe it could be with the indirect method putting the camera behind the screen.
Is that idea abandoned?

Are you guys using 640x480 on purpose?
Do low res low cost chips have the wanted size / resolution / pixels per mm.
So no need/advantage for throwing a few extra pecunia?

So does a laser level loc in position after setup?

Or do you have to trust the deviation is constant / repeatable.

Greetings Bert


Verstuurd vanaf mijn SM-A320FL met Tapatalk

Hi John, Yes with your shadow camera setup you will always have to move the light source with the sensor board, they really need to be bolted together with a gap for the wire. I have used translucent white perspex for led light diffusion before, works really well, you can buy it on amazon.

Quote:

---

Originally Posted by driftspin

Hey guys,

I have been following this thread with great interest. Really great work.

I really like they way the camera + software is used for this purpose. It smells like a commercial oppertunity in my opinion.

Anyway, Since i bought a new house i am about to move my cnc machine in about a month or two.

I think i could use a laser level device for some of the needed remodelling work so that one could pass investment committee.

I would like to use this technique for a check on my machine after transport.

Actually.. it would be the first time and method i could set up for a half decent check on my machine.



So i would like to buy a new laser device with this in mind.

I only have an 8 mm umbilical type usb HD cam atm. So a really small chip.. i guess not usable for this pupose.

Maybe it could be with the indirect method putting the camera behind the screen.
Is that idea abandoned?

Are you guys using 640x480 on purpose?
Do low res low cost chips have the wanted size / resolution / pixels per mm.
So no need/advantage for throwing a few extra pecunia?

So does a laser level loc in position after setup?

Or do you have to trust the deviation is constant / repeatable.

Greetings Bert


Verstuurd vanaf mijn SM-A320FL met Tapatalk

---

Hi Bert,

The sensor in your cam is probably fine, although if the overall dimension of the camera is only 8mm it maybe harder to work with. The VGA sensors we are using are 2mm across.

It seems most of the cheap cameras are vga even though they are sold as HD. It is difficult to determine what the actual resolution of the sensors are without a part number, some are probably higher resolution sensor that are binned to get VGA output. We want a reasonable frame rate for averaging so given the bandwidth constraints of USB2 which most of the cameras talk, VGA can be give us 30FPS.

If you take a 2mm sensor with 640 columns of pixels you get 3um per row which is plenty small enough for what we are doing.

My laser doesn't lock in position, but once allowed to stabalise it doesn't move unless knocked. I only need the laser to not move for one measurement run, as I'm not trying to align to the laser rather to get the errors between the laser and whatever i'm measuring to lie in a straight line. From my initial experiments the laser doesn't move at all over say a 10min session. The Dewalt laser I'm using is damped with a magnet, this probably helps. The laser doesn't even need to be self leveling, this just helps getting it setup.

So the process would be switch on the laser (this moves it a bit), wait for a few seconds for it to stabalise, take N measurements along a rail, switch the laser off, shim the rail, repeat. It doesn't matter if the laser moves between runs.

Cheers, Joe

Hi Joe,

Do you still use it like this?
Or do you also point the laser directly to the sensor now?

Oh btw this is my camera:

https://s.click.aliexpress.com/e/EWnU1gjA

1280x768 i guess.

Hope to put it in the dustshoe later.



Grtz Bert.

https://uploads.tapatalk-cdn.com/201...e77e002841.jpg

Verstuurd vanaf mijn SM-A320FL met Tapatalk

Quote:

---

Originally Posted by John McNamara

Hi Joe
Hi All

I downloaded the next version that displays a graph of the measured points. And look how nice and linear the graph is! .05mm measurement steps on the dial indicator.

Attachment 26370

I ran it 3 times to check.

While testing I moved the light a tiny bit. I had to start again, The light source will have to be rigidly mounted on the platform or you will get errors.

Will the current software work with higher resolution cameras say 1080P? I realize there would be more number crunching for he processor.

Regards
John

---

Great result, would be interested to see what it looks like in 0.01mm steps. What does the residual chart look like? I can see your residuals are all less than one pixel which means your step size was very consistent. Also if you put in a scaling factor in the umPerPixel preference you will get your results in um, or tenths or whatever. I need to make these preference persist between runs.

At the moment the software asks the cam for a vga image, so it doesn't matter what the cam resolution is, I can make this more configurable.

Quote:

---

Originally Posted by driftspin

Hi Joe,

Do you still use it like this?
Or do you also point the laser directly to the sensor now?

---

Hi Bert,

No I just use the bare sensor in a milled fixture, see:

Attachment 26375

Nice work guys. For us laymen, how would this work (once all the problems are worked out) for, say aligning the parallel rails on a Y axis to make them level with each other? Is it just a case of placing the sensor on one rail and the laser on the other and then shimming until the software shows the line dead center of the screen? Forgive my ignorance.

Hi Joe

The M'soft webcam I am using appears to have a sensor active area about 2.5mm wide That would help explain why my resolution results are a little more than 3 microns.

Noise. There is a discussion on the MEW site about astronomical photography and the need to reduce noise. Camera sensors for this application are sometimes super cooled to reduce it. No I am not suggesting this level of sophistication for a webcam. However it may partly explain why the measured value particularly the right of the decimal point is ever changing? the first two digits to the right are very important. If they are stable we get a 100 fold increase in accuracy, maybe impossible but worth striving for.

Catenary sag.
For a DIY person setting up say a router with 3 Metre rails roughly what is needed for 2.4 Metre travel, a stretched wire will sag due to gravity. Using your measured value table as a reference and given an input length the calculation could be applied and the true calculated value displayed. The weight of the wire is almost negligible the applied tension can known, say a barbell weight and needs to be input as a constant also. I am not sure how much work this would be to implement in the software, It would be very useful if it can be done.

One of the advantages of stretched wire is that it is very easy to align to high accuracy, 0.0001" positioning is fairly easy to achieve by placing a precision block at each end of the object being measured. By stretching the wire over the blocks you have very stable line parallel to your work piece.

I will run a set of tests tonight at .01mm increments. and check the residual chart. and work on the light source.

Regards
John

Hi Joe
Hi All

Below two images of a test of 0.25mm in 0.01mm steps.

The Dial indicator used was a Mitutoyo 0.01mm resolution unit. Ideally I should have used a higher resolution unit. I have one but I would need to make a mounting base for it. This would reduce the Measurement error slightly. Having said that the residuals look pretty reasonable. I guess I am splitting hairs here.


Attachment 26385

Attachment 26386

Hi John,

Let me just sanity check your methodology. You have the sensor or wire on a precision positioning system. You move the system in steps based based on your dial indicator and click measure at each step? Is that correct? Just wanted to check you aren't moving the system until the measure value increases by one step then clicking measure as this would always produce a straight line, I don't think you are doing this but just want to be 100% sure.

You have the umPerPixel set to 1 therefore the numbers you are recording are in the units of pixels, this means anything to the right of the decimal point is to a sub-pixel accuracy. This ok to an extent (say 1 decimal place) but will soon deteriorate into noise. The gaussian fit will be afffected by a single intensity point change of a single pixel that is why you get jitter at extreme sub-pixel resolution. To remove all jitter you would probably have to perform the test under lab conditions in a vacuum to avoid dust particles and with a lab quality camera with high precision pixel exposure times. The exposure times (and therefore the intensity readouts) of these cheap sensors with rolling shutters are not perfect, when a pixel/row is exposed for slightly longer its intensity values will naturally be higher. Couple this with the onboard image processing pipeline that is probably trying to do all sorts or AGC and white balance adjustment and noise is inevitable.The image is then compressed onboard to a jpeg adding all sorts of artifacts before being shipped to the PC.

All that said your 0.01mm test run shows your residuals are within +/- 0.4 pixels or 0.0016mm (think you sensor is ~4um per pixel) of a straight line, this is pretty good isn't it? Shimming or scraping in the 1 micron range is most likely impossible for us and probably completely overwhelmed by the thermal movement of the frame.

The 0.0016mm could as you say be down to trying to position the sensor using a 0.01mm dial indicator, quite difficult to judge 1/10th of one division...and outside the tolerance of the indicator.

I can add warping for the catenary sag if you have the equations?

Hi Joe

The measuring system is just a manually driven XYZ platform

Once set up I only move the webcam The light is at this time fixed and non moving. This is wrong! it should move with the webcam sensor although a 0.25mm movement is pretty small slightly less than 0.010 inches. I am going to work on the light next.

And yes I clicked measure after each movement to the next tick on the dial indicator. The straight line is proof that the system is linear. Subject to my possible manual positioning errors as detailed in my previous post.

And the results we are getting are better and better, once the lighting is sorted I am certain the repeatable accuracy can be improved. Once this is done I really want to try a higher resolution webcam.

Regards
John

Quote:

---

Originally Posted by Nealieboyee

Nice work guys. For us laymen, how would this work (once all the problems are worked out) for, say aligning the parallel rails on a Y axis to make them level with each other? Is it just a case of placing the sensor on one rail and the laser on the other and then shimming until the software shows the line dead center of the screen? Forgive my ignorance.

---

That would get the curve of the rails identical but it wont make them straight nor planar.

I was planning on positioning the laser across the room, levelling one rail, the levelling the other rail to the first rail bringing them into plane. For the Y gantry there are some options, you can do it the same as the X and then adjust for perpendicularity when you assemble the machine either by using a square or by using this laser system in tramming mode. Or you can assemble the machine, straighten one Y rail, then use tramming mode to bring the other into plane.

Hi Joe

Just noticed your comment re the catenary sag. Adding this feature to your software will make it exceptional.

The formula is widely cited the Wiki in this case is a good place to start.
https://en.wikipedia.org/wiki/Catenary#Equation

Once your measurement table is filled with points and the user has input a length The catenary sag allowance at each point can be added to the table. The weight of the wire and the tension applied to it need to be added, they do not change so can be stored constants.

Regards
John

Hi Joe

Correction this line my post above
"
The weight of the wire and the tension applied to it need to be added, they do not change so can be stored constants.
"

Should read
The weight of the wire does change according to its length.

Roslau are are a world leader in music wire manufacture.

This is where I sourced my wire. https://parkepianostrings.com.au/pia...als-and-tools/
It costs about $40 AUD per coil plus post. they will ship internationally.

Half KG coils of #2 .010" Roslau Blue music wire contain 1250 metres of wire.

Regards
John

Hi All

Today I received a nice webcam in the mail, a gift from a forum member,Thank you.

It uses a smaller sensor than mine so it will be interesting to see how it performs. I will have to make a new mount for it.
For the tests I will use a one micron Maher milemess indicator. that should assist in getting an even better idea of achievable accuracy.

For any members who live in Australia I will be at the MSME exhibition.
https://www.msmee.org.au/

Our club has been meeting since 1926 in Melbourne new members are always welcome.
Or just pop in at out next meeting as a visitor and have a chat.

Regards
John

John,
I have found a dirt cheap webcam online which is very easy to dismantle which I plan to play with once my more urgent project of working out how to successfully cut wooden gears proves fruitful.

Much as I'd love to come and see you at the MSME I'm afraid it's a bit of a long way from here, even though I don't need to show my passport enroute.

Kit

Hi Kit,

Inkscape has an add-on that will draw involute toothed gears and gear racks. I have used this to input a dxf into Fusion360 to extrude it to an stl for 3D printing. I haven't yet had the need to cnc cut one though. If you want helical cut teeth you are on your own.

Cheers,

Rob

Rob,
Thanks for the information but I use a rather splendid bit of software called 'gearotic' written by Art Fenerty, the creator of MACH3. For anybody interested in creating gears of any kind you can think of, and several kinds you previously couldn't, and especially anyone who wants to design wooden clocks I can heartily recommend it. The program, not unlike Art himself, is a little eccentric and is therefore, in my humble opinion, well suited to many of the regular contributors to MYCNCUK:joyous: The one-off, minimal license fee entitles you to a lifetime of free upgrades.

Gearotic is brilliant for creating the basic gear design. I then export a DXF file to CamBam for design editing and G-code output.

My problem in cutting wooden gears is that those teeth that have the grain running tangential to the gear wheel tend to chip and break off when cutting. Teeth with the grain running radially are fine. I have managed to successfully cut gears from Jarrah blanks created from six segments with the grain running radially all round but the wastage of timber is criminal. I'm currently experimenting with plain pine blanks stabilised with Cactus Juice resin.

Most wooden clock makers use plywood for the gears but, being me, I want to use various types of better-looking plain timber to produce a more impressive result.

I had thought about starting a new thread asking for help on how to cut these gears if the current experiments don't work. I'd prefer not to hijack this existing discussion.

Kit

Hi All

Today I ran a test on a webcam generously sent to me as a gift from a forum member. A wonderful gesture.

I do not know much about the sensor apart from the fact that it appears to be dated 2012.

The test was made using the sensor and .008" piano wire as done before.

When I tested it with Joe's software it counted 93.7 pixel lines to measure 0.2mm
My previous tests with a Microsoft webcam over the same distance of 0.2mm counted 47.56 lines.

The new tests prove the camera given to me has almost twice the resolution of the Microsoft unit.

0.0021mm or 0.00008 inches. per pixel line.

The new camera also displayed less noise and was less sensitive to stray light. All in all a better unit. I will try to find out more about it.

The latest results have really inspired me to to press on with improving the mounting of the camera and better light control. I will report back here with my results. Maybe the Webcam driver software can be used to adjust the sensitivity. That would be useful.

There may even be higher resolution webcam sensors available.... technology marches on.

The accuracy now already achieved will enable the unit to be used to easily test large precision machine tables for flatness if the catenary equation sag corrections can be applied to the measurements.

All this started with Joe's software, Thanks Joe.

Regards
John

Three images below

Attachment 26468

Attachment 26466

Attachment 26467

Quote:

---

Originally Posted by John McNamara

Hi All


All this started with Joe's software, Thanks Joe.

---

Hi John,

You are very welcome, I've been a bit busy with work, great to see you are making progress.

Yes it should be possible to grab higher resolution images from the camera giving you the choice of more dynamic range or adjustable sensitivity.

Cheers, Joe

Did anybody test flatness of the laser beam yet? I'm impressed with results you're getting and just that one question remains unanswered.
I have garde 00 600x400 mm granite plate, one diagonal(720mm) is within 1 micron.
SJ4000 with large sensor and high resolution and can act as webcam.
just no laser...checking ebay...

Hi Sasquatch

If you study the two test series I did with two different sensors you will see that the resolved measurements taken with the second sensor were better with the higher density (The pixel lines were closer together), sensor used for the second set of tests.

No lens was used just the wire shadow.

Devmonkey mentioned that the results were better without a lens when he did tests with a laser. Using a lens with the laser generated distortion? I can also confirm this when I tried using a laser with a lens.

Maybe the standard lens supplied with a webcam or action cam is not the ideal for working with a laser. I know industrial laser cutters use lenses made from Germanium and other exotic materials.

A friend who spent his working life as a physics lab tech also mentioned that webcams will probably have a red filter behind the lens and in front of the sensor. He suggested that this should be removed if working with laser light.

These are only study notes on my part, I wish I knew more about optics. Maybe one of the MYCNCUK members here can give a more qualified view?

Regards
John

Hi John.
My action cam lost lenses in shooting accident (air rifle ricochet).
Flare with lenses is an result of partial reflection on each layer of glass/ plastic beam is passing trough.
My action cam had a infrared filter behind the lenses.
Sensor is about 3x4 mm 1080p gives higher pixel density than 2 mm wide VGA sensor. Should be good.

Can't find any lasers with single cylinder lense. No Dewalt dw088 on ebay UK in acceptable price. Any cheap laser recommendations ?
Edit 1:

Figured out easy and cheap way of testing projected line straightness.
Method requires roughly straight surface, aluminium extrusion should do. Surface must only be flat within sensor measurement area.
line laser
pointer laser
2x camera sensors set 90 degrees to each other.
first camera is following pointer aiming along the beam
second camera is following projected line
With some excel magic we can deduct straightness of projected laser line independently of any beam errors.
Given we can get 3-4 microns resolution on both sensors accumulated measurements arrors should be below 0.01mm in worst case ->just a gut feeling, no real maths behind it so feel free to correct me. That should be more accurate than any straight edge one could buy, as 0.01mm over, say 3 meters, is waay beyond din 874/0. and sag on wire could be greater than 0.01mm too?

Edit 2:
Software feature request:
Can we have adjustable capture resolution,since higher res cameras have bigger sensors allowing wider beams and/or wider measurements range?
Or at least run in maximum supported resolution, whichever is easiest.
Also when requesting VGA stream from 1080p sensor camera firmware is scaling each frame introducing errors.

Edit 3:
Created pull request on GitHub with more resolutions possible.
Unfortunately i can't figure out how to add menus to change resolution nor how to pass resolution via command line parameters.
Just edit settigs.java and rebuild to required resolution, supported are 320x240,640x480,800x600, 1280x720 and 1920x1080.
Hope that @devmonkey don't mind and will add settings menu in free time.

Sasquatch,

I haven't got one myself but this laser looks very promising with a glass cylindrical lens.
https://banggood.app.link/PPKk7DZpR0

Will integrate your resolution changes when I get time.

Cheers, Joe

I've committed a change so that it determines the maximum native resolution of the camera and uses that, please test.

Cheers, Joe

Quote:

---

Originally Posted by devmonkey

I've committed a change so that it determines the maximum native resolution of the camera and uses that, please test.

Cheers, Joe

---

You're a star Joe.
But it defaults to 640x480 on SJ4000. "proper" webcam could be working ok, although windows10 camera app detects it as 1280x720(max video output for sj4000)
Saying that, SxrosCamera by default don't support anything above 640x480, hence you have to define custom dimensions for higher resolutions.
It defaulted to maximum resolution supported by SxrosCamera without custom dimensions defined.
Cheers Les.

Quote:

---

Originally Posted by Sasquatch

You're a star Joe.
But it defaults to 640x480 on SJ4000. "proper" webcam could be working ok, although windows10 camera app detects it as 1280x720(max video output for sj4000)
Saying that, SxrosCamera by default don't support anything above 640x480, hence you have to define custom dimensions for higher resolutions.
It defaulted to maximum resolution supported by SxrosCamera without custom dimensions defined.
Cheers Les.

---

So we can't make it automatically pick the max resolution? If we pick the wrong one presumably it crashes the driver? I don't have a higher res camera to test with.

Edit
Ok so it looks like Sarxos is using a driver on Windows that doesn't do resolution detection, are you using windows? We could change it so that we force a specific driver per platform but then it becomes a bit of a nightmare to package. Will have to have a think.

Yes I'm running it under windows.
If I only change resolution to anything above 640x480 in settings.java it crashes saying that correct resolutions are 174xsomething 320x240 and 640x480
Defining custom dimension as per sarxos manual and FAQ(look at my pull request) allows to select any resolution. I tried 4000x3000(max res of my sensor) but image quality suggested it was still 1280x720, makes sense.
Maybe defining custom resolutions and then autos election would work?

The trouble with asking for a custom large resolution is the camera encoder chip can choose to scale it for you if it is larger than the sensor. It seems there is no reasonable solution without forcing a windows specific driver which will actually query the camera for the supported resolutions. Will look into this when I have more time. Almost all cheap cameras makers lie about the resolution of their sensors as well so we can't rely on the user inputing whatever resolution is 'written on the box'.

I did look at your pull request, but I don't think it works generally for everyone as if you request a non-native resolution the camera chip can choose to scale it for you.

Totally agree on my pull request, not suited for all(most?) cameras.
My understanding is that sarxos don't support higher resolution at all, unless you define them. At least that's what i understood from quick look at sarxos examples ad faq. I may be completely wrong.
My idea is to try defining "custom" resolutions and then running auto detect. I'll try it tomorrow afternoon, as now i left camera at workshop.
But before that I'll try your auto detection solution under Linux, Ubuntu and PureOs(both debian based).
As for now i can't even check benefits of higher resolution as my laser pointer is extremely noisy and line laser will twke 7-15 days to arrive, absolutely no pressure.

Jar from GitHub loads on Ubuntu, detects max resolution as 640x480 then fails. i'm getting blank window and null pointer exception in NextFrame method.

Built from GitHub source on Ubuntu runs ok, detects max resolution as 640x480.

It is indeed driver issue, apparently there is no single driver working on all platforms, those working in Windows/Linux won't work on Mac. And those working on MAC/Linux won't work on Windows.

Just make an option in preferences to select resolution. People using that kind of software should be techie enough no know how to check max supported resolution of their camera?

Did some testing today. SJ4000 gives resolution of 3.75um per pixel in 1280x720 video mode. 4.8mm active sensor width.
If LaserLevel could work with stills, I could get 1.2um per pixel from that camera. Waaay too sensitive, or is it?

My laser finally arrived, and...judge yourself.
camera fitted in precision vice riding on grade 00 18"x 24" granite.
Running across the beam i'm getting 0.04mm deviation from straight line on ~500mm distance
Running away from laser I'm getting 0.02mm deviation on ~500mm distance.
Beam is changing width and apparently this change is not symmetrical.
I was getting same results with pointer laser(runnig away from it), but assumed that irregular dot with surrounding artefacts was to blame.
It's still viable way of checking linearity, but as shadow camera and wire. Cheap(£25, glass lens, 80 MW) lasers are not precise enough. maybe £500 line laser could be used, but for such money there's plenty other options.

My laser finally arrived, and...judge yourself.
camera fitted in precision vice riding on grade 00 18"x 24" granite.
Running across the beam i'm getting 0.04mm deviation from straight line on ~500mm distance
Running away from laser I'm getting 0.02mm deviation on ~500mm distance.
Beam is changing width and apparently this change is not symmetrical.
I was getting same results with pointer laser(runnig away from it), but assumed that irregular dot with surrounding artefacts was to blame.
It's still viable way of checking linearity, but as shadow camera and wire. Cheap(£25, glass lens, 80 MW) lasers are not precise enough. maybe £500 line laser could be used, but for such money there's plenty other options.

Do you have any pics of your laser and sensor? I think there is something strange going on with your setup if you see errors moving the sensor along the laser axis. Is the laser spreading? Have you removed all optics and filters from the sensor and bolted the pcb to something solid? We do know that the laser beam is not bending in the air so something else is wrong.

Bare sensor, unless there is anti aliasing filter glued to silicon, but AFAIK it's DSLR's area.
Stripping further is not really an option, not usable as shadow camera as there are modular PCB's perpendicular to the sensor sticking above it's surface. Webcam incoming.
http://sasquatchv.eu/images/2019/11/06/DSC_0048.md.jpg
http://sasquatchv.eu/images/2019/11/06/DSC_0049.md.jpg

Cable is clamped, moving laptop around has no impact on measurements when camera is stationary.

Thinking about it makes no sense.
Both lasers are focusable, both are set to project same width/size line/dot at 8 meters and 20 cm.
They might be represented as
http://sasquatchv.eu/images/2019/11/...0005756.md.jpg
Laser diodes are not perfect, if one edge is brighter (double line above) average brightness will still be straight line
Pointer produces coupe stray beams right next to the main point, that could be source of the problem.
with line laser i have no idea.