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. :)