DIY Laser levelling using webcam and laser level

[devmonkey]

Hi Michael,

Do you have a view on how flat the projected plane of a cylindrical lens laser line is likely to be? This is something I still haven't measured as I have no large enough reference plane.
Along a given ray it should be absolutely straight but will it undulate across 'rays'? By ray I mean a line from laser source to sensor.

My latest thoughts on how to measure this was to place four pillars in a square on a reasonably flat stable surface (concrete floor). Place the laser so that it projects across the tops of the four pillars and use height readings from 3 of them (as any 3 points will be planar) to bring the fourth into plane with some shimming. Now move the laser around the room and have it cast a different area of the beam over the pillars and measure again, check if all 4 pillars are still planar, repeat this a few times.

Thanks, Joe