DIY Laser levelling using webcam and laser level

[John McNamara]

Using wire has the advantage over a laser beam when it comes to defining the boundary of the image formed on the webcam Microscope sensor. the thickness of the wire is known. and depending on the magnification of the microscope it will cover a certain number of pixels. There will always be aberrations; if the image not perfectly focused or if the lines in the camera sensor are not perfectly aligned to the wire. The the existing algorithm corrects for a fuzzy image rather elegantly.

Placing a black background behind the (illuminated wire) provides a very sharp contrast.

As I posted I got very good results using a manual lash up. using a micrometer. This method will provide all the data needed to flatten a surface. (Sag in the wire amounts to a couple of tenths over 2400mm, 8feet) You can use the Catenary formula to correct your measurements if you require higher accuracy.

The machine I posted on Grabcad simply automates the process and employs a small cutter to flatten a surface in this case held vertically, No sag to worry about. It moved the camera (It is mounted on the cutting head slide) until it is centered on the wire then makes a tiny cut. It will be a slow process, several hours but in the end there will be a very flat surface developed.

If this goes ahead I better dig up the ball screws and linear bearings I bought for this project. :)

[John McNamara]

GrabCad Model

I made a 3d Model to be made from laser cut parts that should be able to prove the viability of using stretched wire and a webcam microscope sensor.

The design uses two webcams to sense two suspended vertical wires with a weighted end suspended in Oil. This will guarantee that the two wires are parallel in two planes. This will eliminate any twist in generated surface, it will be a true plane.

I designed the mechanism using a laser cut frame and 100mm square tube and parts I have on hand.
There is minimal machining to do mainly small size lathe work.

To clear up any uncertainty The webcam sensor is moved mechanically until the image of the wire is Is centered on the webcam sensor. The size of the image will be determined by the magnification used. Small errors in the optics can be ignored as we are always using the same part of the lens.

https://grabcad.com/library/machine-...linear-rails-1

[BryanHoward]

I’ve got the whole python tool complete in comparison to the java tool minus an export csv button. Some other things I’ll add which would be nice - replacing the selected sample in the table with a new one. https://github.com/bhowiebkr/laser-level-webcam

Edit instead of adding another post bump. I've made another version fixing with export and some visual feedback on selecting table samples, a replace sample button which I'll find very useful as I can adjust an area and resample over and over till it's where I want it. Tooltips on everything so you should be able to figure out what everything does by just hovering over the widgets.

[BryanHoward]

Here's my first real test of measuring the flatness of my gantry with a laser and webcam sensor. I’ll have to modify the laser level to disable the self-levelling of it because it’s wobbling all over the place.