DIY Laser levelling using webcam and laser level

[devmonkey]

Just a quick one but surely if you are going to use a image sensor it is easier to reference off the perfectly straight laser? I'm also not sure why the stepper motor part is needed, wouldn't you just read the error straight off the image sensor and convert pixels to um?

In my opinion and how I visualise this is you are only ever measuring errors to a known reference you don't need to be parallel to it whether it is a wire or a laser or a precision straight edge. What you are trying to do is ensure these errors lie on a straight line, or in the case of two rails in the same plane.

If you want to use the cmos sensor as a shadow camera without optics my software would work if I inverted the image intensity as you'd get a guassian shadow from a round wire strongly back lit. Mechanically with no optics you need the wire very close to the sensor which may complicate things both wrt protecting the sensor but also aligning your wire in the first place. I would just rebuild a USB microscope at fixed focus in an aluminium block.Ideally you need to measure in 2D not 1D so you can set it straight in both dimensions at the same time, this can be done with two microscopes setup orthogonally on the same block. With a normal dot laser (if you are worried about twist then use a cross laser) pointed directly at an image sensor you are measuring 2D with a single sensor, with a wire you would need two sensors as you cannot 'look' down the wire. The cheap £15 microscopes on Amazon at mid resolution have a depth of field that could maintain focus on your wire if your setup error is within 0.5mm or so. Just be aware that you have to remount the guts of it in something rigid as the assembly that lets the optics slide in and out and the part that holds the sensor pcb can wobble. The latter reason is why i've dropped the optics all together as it simplifies mounting it.