DIY Laser levelling using webcam and laser level

[devmonkey]

Hi John,

I've put up the first version of the wire app here:
https://github.com/betzuka/laserleve...uilds/wire.zip

Extract and run wire.bat, needs java installed as per the laser app. The wire needs to be crossing the rectangular field of view of the sensor in the short dimension, e.g. if your sensor is 640 wide by 480 tall wire should be crossing the sensor from top to bottom.

It doesn't care whether it is looking at a bright wire on a dark background or vice versa, just needs a decent contrast and the microscope focused so that the wire edges appear reasonably crisp. My fishing line is just black mono filament, super cheap kids stuff that I already had. The main reason for the different algo from the laser is that the objective is lit from the front rather than behind, so it isn't acting like a shadow camera, this means you get lots of reflection off of the surface of the wire which would misslead anything searching for a gaussian, or indeed searching for anything other than the wire edges.

Your idea of using it to check for planar surfaces is brilliant ! I could stand my machine on end, drop two plumb lines and measure the relative error between the two lines from each respective rail.

At some point I will integrate it into the laser app so all the other error plotting stuff works. Do you have a microscope to test it with? If not this is the one I'm using, it is also very handy for SMD soldering etc.
https://www.amazon.co.uk/Microscope-.../dp/B07BF86SRP

Cheers, Joe

[John McNamara]

Hi Joe

I do have an optical microscope, A cheap student version I used to align my lathe in 2011 using wire. The is a longish post here that discusses lathe alignment and wire, https://www.model-engineer.co.uk/for....asp?th=136771 In this case I lashed up a measuring stage that allowed me to position the wire centrally in a slot by eye using my bio computer then measure off the error using a micrometer. It worked! Page down the thread to see photos.

In particular note the simple wire positioning stages clamped to the lathe bed made from scrap steel, rock solid.

Using a USB webcam or microscope with your software is clearly a better solution. It eliminates a number of sources of error.

I don't have a working USB microscope I will order one! I cant wait to test the software.

In many ways two cameras will be even more useful, for XY measurement, Ideally using one computer, although old PC's are easy to source for nothing or next to nothing, if two instances of the software could interface to two USB ports on one computer it would be more convenient.

Regards
John

PS stretched wire plumb lines are used to this day by heavy machinery installers, for instance passenger lifts and giant boring mills to align the column. Normally the bob weight is suspended in a container of thick oil to damp out any tendency to sway like a pendulum.