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Topic: Ebay laser + arduino uno (Read 1 time) previous topic - next topic

8bitbacon

Hi i bought a 50mw laser that u can pretty much see the beam line at night. Anyone know if its possible to change the distance length it emits from 10 miles to like say 3 feet instead.
arduino mini woot

PaulRB

Hi i bought a 50mw laser that u can pretty much see the beam line at night. Anyone know if its possible to change the distance length it emits from 10 miles to like say 3 feet instead.
Hi. Put a concrete block 3 feet in front of it.

Grumpy_Mike

Hi i bought a 50mw laser that u can pretty much see the beam line at night. Anyone know if its possible to change the distance length it emits from 10 miles to like say 3 feet instead.
Yep, change the laws of physics, that should do it.
Any light once created will travel to infinity in this universe, so block it as suggested or get yourself another universe.

Paul__B


8bitbacon

Lol. If i find a way i guess ill repost back here.
arduino mini woot

PaulRB

Lol. If i find a way i guess ill repost back here.
If you do, I hope you will invite us to your Nobel Prize ceremony!

8bitbacon

i probably will just invite you to a light show
arduino mini woot

DrAzzy

The distance that the beam is visible to at night depends on the brightness of the light, and how much dust and crap is in the air, as well as how well focused the beam is. There isn't a good way to limit the distance of this other than having it hit something.

If the room is full of smoke, even a very weak laser will have a visible beam - but the air is normally pretty clear, which is why you need such a powerful laser to make the beam visible.

Be very careful not to shine it at planes in the sky, they *really* don't like people doing that.
ATTinyCore for x4/x5/x61/x7/x8/x41/1634/828/x313 megaTinyCore for the megaavr ATtinies - Board Manager:
http://drazzy.com/package_drazzy.com_index.json
ATtiny breakouts, mosfets, awesome prototyping board in my store http://tindie.com/stores/DrAzzy

PaulRB

#8
May 24, 2016, 08:47 am Last Edit: May 24, 2016, 08:50 am by PaulRB
The distance that the beam is visible to at night depends on the brightness of the light, and how much dust and crap is in the air, as well as how well focused the beam is. There isn't a good way to limit the distance of this other than having it hit something.
The point Mike and I are trying to make is that, assuming it is not blocked, the beam goes on forever. It does not stop after a certain distance. Its intensity drops according to 1/r^2 in a vaccum, so if you move twice as far away, the intensity drops to one quarter of the intensity at the source. There comes a point where it is no longer visible, as DrAzzy says, but that depends how sensitive your eyes or equipment are, as well as how much dust it is passing through.

ElCaron

Sorry to dig up corpses here, but I followed the thread starters history after his last Dunning-Kruger excess. It is pretty entertaining :) AS I am on it, I might as well correct a small thing:

The point Mike and I are trying to make is that, assuming it is not blocked, the beam goes on forever. It does not stop after a certain distance. Its intensity drops according to 1/r^2 in a vaccum, so if you move twice as far away, the intensity drops to one quarter of the intensity at the source.
A laser beam is not a point source with spherical emission, it does not drop of with 1/r^2 like radio waves from an undirected antenna. The intensity drops with the beam divergence. The intensity does drop quadratic to the diameter, which also does increase linearly with the distance to the source, but it does not start at zero. A good laser will have almost the same beam diameter after 2m as after 1m. 
It is often even pragmatic to assume no divergence at all at smaller distances, resulting in a constant intensity.

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