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.