DIY Laser levelling using webcam and laser level

[BryanHoward]

I’ll have to read up on the wire version, I saw mention of it buried in this thread but couldn’t find the description on how it works. I suppose it is along the lines of finding the center of a thin wire using a webcam sensor with a 40x-100x optical element on it? Correcting for the gravity dip over the span of the wire length?

I want to use this to measure the flatness for the surface of a single linear rail.

You mean the conical reflector in self leveling 360 degree lasers is just not good enough? I was thinking about that too but I guess if I’m trying to get just the surface for a linear rail flat all I gotta do is have the surface and the laser beam collinear? Then the precision of the reflector won’t be a factor.

I’ve found this whole method work well with a single point red laser pointer but without the IR filter it tends to blow out the sensor pixel values. It might work better in my case because the “self-leveling” part of the self leveling 360 deg lasers wobbles all over the place.

I don’t think I'd be able to get down to 1 um of flatness on the rails but if I can get down to 10um id be happy.

I’ve got most of your original code converted to python. I need to get the raw points transformed from the fitted line figured out and I’m not sure what you are showing in the scrape and shim vs the residual columns. I thought those should be the same?

Anyways, here's what I’ve got so far. I’ve found around 100 sub samples and throwing out up to 50% of the outliers gives me the most accurate measurements. I turned the camera on without letting it warm up so the values drift up and takes about 5 min of running before it equalizes. It kinda runs slow when recording and it not being compiled to C with nuitka.



Here is with a red laser pointer. Sensor gets blown out so probably need a filter or Neutral density (ND) filter so the peek isn't flat/clipped. Furnace turned on so there is a bit of vibration as well as not getting warmed up.

[devmonkey]

My wire version I used for straightening a rail that was already sitting in plane with its pair since the surface had been epoxy leveled, it was looking down on the wire from above so gravity wasn't an issue. Your setup will work for a single rail in 1D as you have it setup in the video with the laser firing down the rail but you couldn't use it for bringing things into plane as the laser surface is not flat enough. You need a really expensive lens for generating a flat surface, if you look up commercial products for leveling machines in this way you can see the price of the laser source, that is all going into the lens.