Thread: DIY Laser Level
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Ian Stirling
 
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Default DIY Laser Level

Ian Stirling wrote:
david lang wrote:
Ian Stirling wrote:

It won't send a little red dot a hundred feet.
The cheaper units typically have a divergance of around half a
milliradian. For less divergance, you need to be able to focus onto an
objective, and have a bigger lens.
The cheaper ones will do a spot of maybe 5cm at 100m, and this is
trivial to see at dusk.


Mine will shine a red dot onto the chimney of a house at the end of the cul
de sac, well over 100 ft away. Granted I don't know how big the dot is, but
it certainly reaches that distance.


True - but the dot it sends is not little.
At 100 feet, you're looking at 2-3cm or so.

If you're next to the dot at night, you can probably see it perfectly
well until the dot gets to well over a meter.

And then - looking towards the laser, it's visible when the spot is many
tens of meters wide.


I should have mentioned - that I've also used a laser pointer, a bit of
15mm pipe insulation to grab it, and a bit of waste pipe, to slip a
laser pointer into accurate alignment with a pair of binoculars.
The binoculars then form a beam expander, and greatly reduce the
divergance.