DIY Laser levelling using webcam and laser level

[devmonkey]

Hey guys,

I have been following this thread with great interest. Really great work.

I really like they way the camera + software is used for this purpose. It smells like a commercial oppertunity in my opinion.

Anyway, Since i bought a new house i am about to move my cnc machine in about a month or two.

I think i could use a laser level device for some of the needed remodelling work so that one could pass investment committee.

I would like to use this technique for a check on my machine after transport.

Actually.. it would be the first time and method i could set up for a half decent check on my machine.



So i would like to buy a new laser device with this in mind.

I only have an 8 mm umbilical type usb HD cam atm. So a really small chip.. i guess not usable for this pupose.

Maybe it could be with the indirect method putting the camera behind the screen.
Is that idea abandoned?

Are you guys using 640x480 on purpose?
Do low res low cost chips have the wanted size / resolution / pixels per mm.
So no need/advantage for throwing a few extra pecunia?

So does a laser level loc in position after setup?

Or do you have to trust the deviation is constant / repeatable.

Greetings Bert


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Hi Bert,

The sensor in your cam is probably fine, although if the overall dimension of the camera is only 8mm it maybe harder to work with. The VGA sensors we are using are 2mm across.

It seems most of the cheap cameras are vga even though they are sold as HD. It is difficult to determine what the actual resolution of the sensors are without a part number, some are probably higher resolution sensor that are binned to get VGA output. We want a reasonable frame rate for averaging so given the bandwidth constraints of USB2 which most of the cameras talk, VGA can be give us 30FPS.

If you take a 2mm sensor with 640 columns of pixels you get 3um per row which is plenty small enough for what we are doing.

My laser doesn't lock in position, but once allowed to stabalise it doesn't move unless knocked. I only need the laser to not move for one measurement run, as I'm not trying to align to the laser rather to get the errors between the laser and whatever i'm measuring to lie in a straight line. From my initial experiments the laser doesn't move at all over say a 10min session. The Dewalt laser I'm using is damped with a magnet, this probably helps. The laser doesn't even need to be self leveling, this just helps getting it setup.

So the process would be switch on the laser (this moves it a bit), wait for a few seconds for it to stabalise, take N measurements along a rail, switch the laser off, shim the rail, repeat. It doesn't matter if the laser moves between runs.

Cheers, Joe