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FrozenGate by Avery

laser dot pics at distance??

A

adamf

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May 17, 2010
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looking for images of laser beams over a mile or so but cant find any thanks...
 





Nice shot RA! Must be nice to have mountains when your trying to find stuff to point at. I have to find the water towers around my house :p. I've seen the spot up to three miles, but no pictures. Once my new laser and beam expander get here I'll try an get some pics.
 
well i have my whole setup now(400mw green with no duty cycle,tripod,tripod mount lg. ,lg.x10 expander, cell phones, camera,car.).... when i find some time i will be taking some cool pic.s plus measurements... i really cant wait..i did some 400yrd tests it was amazing how much difference x10 made...
 
Looking for a pic of the dot at say 1 mile to see how big the dot would be.. Thanks
 
That one RA posted is over a mile. I think he's said that hill is about 1.7 miles away before, but that could be a different hill. That doesn't really give you an idea of how big the dot is though. The spot should be about 2m across a mile away if you're using a green laser with average divergence.
 
is there a table out there to sey eg every 100 metres the dot gets bigger x1 etc cheers
 
No, but it is very easy to figure out how big the spot will be. Every laser has a specific divergence. Divergence is a measure of how much the beam expands. Divergence is measured in "mrad". A typical green laser has a divergence of 1mrad to 1.5mrad. mrad simply means that for every meter travelled the beam will expand a constant amount. The number before mrad is the constant. It tells you how much the beam diameter expands in millimeters for every meter travelled. 1 mile is about 1600 meters, so you take the number before mrad and multiply it by 1600. Say it was 1.25 mrad. That would give you 2000mm which would be 2 meters plus the original diameter.
Would you like me to explain to you how to measure divergence?
 
kevinmassey said:
That one RA posted is over a mile. I think he's said that hill is about 1.7 miles away before, but that could be a different hill. That doesn't really give you an idea of how big the dot is though. The spot should be about 2m across a mile away if you're using a green laser with average divergence.
Click to expand...

It is about 1.7 miles.
The divergence is 0.8mRad @ 2mm beam diameter.
I'm too busy to do the math right now, though.
 
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