Originally Posted by
TiredSoul
I’ve got a $15(?) flashlight/laser combo I bought years ago at Home Depot.
Runs on 3 AAA and the laser easily reaches a mile. Looks like it’s about basketball size “dot” at that distance.
At 6 miles that would be large enough to cover the cockpit.
Like Rick said, mine wouldn’t be strong enough at that distance to be damaging but certainly feasible.
More complicated than that, it's not linear.
The beam stays pretty tight out to a certain point (the Rayleigh range). After that point, the beam starts to diverge more significantly, quickly becoming useless for power delivery.
The Rayleigh Range is a function of aperture size, so in order to push out the RR far enough to be a useful long-range weapon you'd need a large aperture. Bubba (or al queda, etc) cannot build such a thing. Since the vast majority of legit laser applications are short range and/or low-power, there are just not a lot of large-aperture lasers in existence, outside of mil, R&D, and academia. Even a very powerful industrial laser would probably turn into a flashlight before it reached long ranges... it's designed to cut things at a range of millimeters, not miles.
This is an example of a long-range laser designed as a weapon against distant airborne targets. Note the aperture size. Also note that it requires a 747 to haul it around...
Obviously a long-range weapon designed to injure human eyes would not need that ^^^ large of an aperture, but probably bigger than what you can readily obtain commercially. How big do you need? Not sure, have to do the math (also varies with wavelength and other factors).
Also lasers which are designed to blind (as opposed to dazzle) humans are illegal under international convention, so you can't even steal one from a military arms depot.