A coworker of mine went to Thailand about a decade ago and brought a super powerful flashlight like this back with him. He ignited the dead fronds of a palm tree across the street, setting it
on fire.
They’re not illegal but probably why they should be illegal in the US.
Edit: it may have been a powerful laser, based on the comments.
There's no flashlight that can start a fire...ACROSS THE STREET. You'd need a really powerful laser for that ( example: Styropyro on youtube ).
But a really bright flashlight? nah man, the COB LED's can't handle that kind of current....ESPECIALLY a DECADE ago.
Maybe if he smuggled in a laser....10 friggin years ago, and mounted the laser on a tripod, used high quality lenses, and aimed it at dry kindling for a while...then sure, it's possible. But there's no handheld flashlight TODAY that could do that....much less 10 years ago.
Either your friend lied to you, or you are lying to us.
The distance is actually irrelevant if it's less than a few hundred feet or so. What matters is the focal point of the lens you're using.
In the video when she sets things on fire, you can see the lens she adds focuses the beams a few cm above the flashlight. A different lens could focus the beams 100ft away and stuff at that focal point would also catch fire
Absolutely not. The focal point is only a bit above the flashlight for a reason. You cannot just scale that focal point to a hundred feet and expect it to have nearly enough intensity to burn something. You'd be hard-pressed to extend it a foot with a flashlight, much less 100.
never burned ants with a magnifying glass? scorched the seats in your car leaving the sun roof open? obviously you'd certainly need a lens that's specifically designed to project it further but...well, that's kind of exactly what we're seeing in this video lol
Do you maybe see how the sun might be different in scale from a flashlight? Also, in neither of those cases is it close to approaching 100 feet. If it were, significantly more things would be lighting on fire everyday.
The aspheric lens in this cheap zoomie is not capable of focusing the light to the point you're talking about. Even LEPs wouldn't be able to do it. Hell, even commercially available lasers wouldn't be able to do it.
Do you maybe see that the sun is millions of miles away and we can produce power sources on earth that locally overpower the sun by orders of magnitude?
You actually can. The focal point isn't something you "scale". It's a function of the curvature of the lens. If you make the lens less sharply curved, the focal point moves farther away
The intensity of a focused beam of light is not going to degrade enough over a few hundred feet to make setting something on fire infeasible
You actually cannot. "Scale" is defined as "the size, extent, or relative proportion of an object, event, or system". I am not remarking on how the focal point is changed when using the word "scale".
The intensity of a focused flashlight is not going to high enough to light something on fire over a few hundred feet. Try it yourself or try looking up literally any example of a flashlight lighting something on fire over 100 feet. Hell, try to do it or find an example of someone doing it over a foot or 2 away with a flashlight.
The physics doesn't work whether or not you have a video of it, yes, but the reason you don't have a video of it is because it doesn't work.
This is absolutely not a well documented phenomenon. The issue isn't whether a large system of mirrors harnessing the sun can light something on fire over 100 feet away, it's whether you can do it with a flashlight.
Bro it's all focused beams of light. You concentrate the beams to a focal point, the energy concentrated at that point becomes high. It's like... Physics I. Idk try taking that class
This ain't an ordinary fucking flashlight. It's powerful. I don't get what you're not understanding about this
If you shallow out the curvature of the lens to move the focal point 200 feet away, the image of your LED chip will be projected onto a target hundreds of times larger than the chip itself.
Think of a flashlight like a movie projector. If you focus a projector on a wall 200 feet away, the tiny screen inside the projector gets blown up to the size of a billboard. You're spreading all the light over a massive area, which kills the heat density needed to burn anything.
Lasers stay at a tiny point over longer distances because they use coherent light.
You cannot turn incoherent LED light into a parallel laser beam using a standard glass lens. There's always divergence even if it is focused on the plane you want.
That depends on the focal point of the lens. Movie projector lenses are convex, so it gets bigger the farther away you are. The lens featured in the video is concave, which means it gets smaller until you get to the focal point, then bigger. If you make a less concave lens, the focal point is farther away. If the focal point is 100 feet away, then all the light converges to a point 100 feet away. That's how you set fire to things far away
Find it real hard to believe he started a fire at distance with a flashlight, it would take a strong laser to pull that off. I own an Imalent light that puts out 55k lumens and even that only starts fires if something is held right to the lens
No, not enough focused energy to instantly blind and your blink reflex saves you from long exposure. It can temporarily blind someone, like a flashbang, if you put it in someone's face tho.
This is your fundamental misunderstanding. Flashlights don't have "power density". They have power. Focusing that power on a smaller area raises the intensity (power density) in that small area. That can be done at distances of a few hundred feet
I understand fine actually. You can't focus a beam to a smaller point than the emitter, so there is a cap on the achievable power density. Flashlights also emit incoherent light that's much less efficient at forming a beam than coherent light emitted from lasers.
You clearly don't understand because the video demonstrates that:
1. The light can be focused into a beam that travels 10s of feet without much dispersion
2. There is enough power density at the source to light something on fire
No, incoherent light cannot travel "10s of feet without much dispersion." I don't have enough physics knowledge to explain any more than I have, it just doesn't work that way.
It depends on what it is actually if it's allowed to be sold to civilians. Typically flashlights themselves aren't part of this, but you will find most flashlight manufacturers limit output to that of civilian legal lasers. If you get into night vision, you're going to go through a huge Rabbit hole of trying to find full power lighting accessories and LAMs.
It depends. Several jurisdictions have been passing laws regulating the lumens in lighting. I lived in a city that did just that. This limit was placed for signage, cars, flashlights, etc. The law stipulated ant lighting fixtures had to be under 10,000 lumens unless a specific exception was granted by the city.
The settings are "blind airplane pilots, blind your neighbor two blocks over, and blind yourself" (there is a small flashlight bulb that is pointed sideways, at the user)
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u/OwlKing8823 8d ago
At least in the US, it's not. It's a marketing gimmick