Re: Does range really affect a lasers ability to b
A couple of main factors..
1. As you said, air itself and the air's quality. You can see the beam because it is reflecting off inpurities in the air(dust,smoke,etc.) everytime some of this light reflects, the beam loses power. The farther it travels, the more power is lost, although within normal burning distances, this isn't a factor unless we are talking BAD air.
2. Beam divergence.. Our lasers burn because there is enough light energy focused on a tiny spot, and when the light hits material, especially dark material, it produces heat. As the beam travels out, it gets wider. For example, my 150mw green's beam is approx 1mm in diameter as it exits the aperture, and by about 4 mteres away, it is over 3mm wide. Now I can see the spot on a white house 3km across the valley where I live, BUT if I look through a telescope, the spot is almost a half a meter wide! This is hard to notice with the naked eye, though, same as looking down a road and it appears to be thinner at a distance. Some lasers let you focus.. the beam will get smaller as it travels to the focal point, then wider as it gets farther past the focal point. Of course the focal point is the best burning point. Better optics mean better burning, BUT even if you can focus at more than say 10 meters away, you won't be able to burn as well becaus of energy loss due to impurities in the air and the air itself. Seems most greens(with naturally worse beam divergence) are lucky to pop a balloon past 5 meters. Focusable greens can manage this feat at sometimes 18 meters. Reds appear to be the superior burners, mostly because of a larger starting beam resulting in easier focusing.
Of course the output factor has alot to do with this. more power means burning is possible with a wider beam/longer distance.
So in short, yes. distance is a big factor in burning capability.
Popping baloons at a fair at 1/4 mile takes one HELL of a laser.. There are a few guys in here with capable modules I am sure, but I bet they paid good $$ for them, and I REALLY doubt they are handheld pointers. Not to mention of course holding the laser stable, and firing at a very likely moving target. Most of our lasers require at least a half second of being held steady on one spot to pop the balloon. :-/
But it doesn't matter, air absorbs and scatters light, thats why the sky has a colour and is not transparent and black so you could see stars in daytime.