China's ‘Laser AK-47’ Can Set Fire to Targets a Kilometre Away | Hacker News Reader

China's ‘Laser AK-47’ Can Set Fire to Targets a Kilometre Away

scmp.com

17 pointsmhb27 comments

So in ideal conditions you have a big, heavy gun that can sort of harm an immobile target that isn’t using basic countermeasures. Meanwhile a BMG .50 rifle can put a hole in an engine block from twice the distance, is cheaper and more reliable, and never runs out of juice.

Way to put the “PR” in PRC.

You can track a bullet though, this seems to be completely invisible to naked eye so you could put a house on fire (since it seems to be pretty hot) and nobody would know.

Serious question: assuming the structure is burned beyond recognition, would arson specialists be able to tell if a house were put on fire in this manner?

No, though they might be able to tell you where the fire started.

Lasers only travel in straight lines, and any moisture or dust will reveal its trajectory and draw a straight line to the shooter. Worse, you need to keep the laser on target for a while. With a .50 BMG sniper rifle you can be moving before the sound of the bullet reaches the target.

No, an invisible infrared beam reflecting off of dust or water vapor is still invisible infrared light.

Fair enough, but those wavelengths are visible with night vision gear. Either you work in visible wavelengths and worry about dust, or you work in IR and draw bright lines for anyone with NVG.

It would have to be night time or otherwise dark and there would have to be enough dust/whatever in the air and you'd have to be expecting a laser attack. And then you'd have two seconds to follow the 'shot' back to its origin.

In order...

It would not have to be night time, modern NVG is quite adaptable. It would also be trivial to deliver something using the same tech as primative NVGs or basic FLIR as a countermeasure.

Dust isn’t required with IR, the whole beam will be very visible on NVG.

Where are you getting “2 seconds” from as the time necessary to kill someone with this laser?

I believe "2 seconds" is in reference to the following sentence in the article:

> It can fire more than 1,000 “shots”, each lasting no more than two seconds.

The implication being not that you have two seconds to kill someone but that you have two seconds to follow the beam from its destination to its origin.

Article states a 'shot' lasts no more than two seconds. Who said anything about killing? The use case seems to be incapacitation and starting fires.

Why would particulate matter in the air not be required? There's plenty of video on youtube of IR laser pointer operation through night vision. It works the same as a visible laser.

Given you have IR laser detecting equipment suitable for daytime use (I'm not convinced your could adapt existing night vision equipment to the task) that would still require you to be expecting a laser attack to deploy it.

Come to think of it, it's not a given that the weapon even uses a wavelength visible to night vision devices. They don't cover all of infrared.

There's a certain irony in people on a technology site dismissing the deployment of an entirely new tactical option that offers several advantages. I'm particularly perplexed by your suggestion that a BMG rifle 'never runs out of juice' as if they came with infinite ammo or something.

Consider this: if you get shot at by a BMG you'll know about it, and possibly be able to figure out where the attack came from. If you just have things silently bursting into flame it may not even be obvious that an attack is underway. And rechargeable batteries strike me as having distinct advantages over expendable ammo. Every building and vehicle is an ammo locker.

A laser's aim doesn't require elevation to compensate for drop. Its aim is also not perturbed by wind, though affected by refraction due to air temperature differences, and attenuated by smoke/fog/dust, which also reveal its path.

It’s also seriously impacted by bloom on the target, which is trivial to produce with even moderate shielding. There’s a reason some very smart people still struggle with adaptive optics and phase arrays, instead of revealing comical sci-fi “weapons”.

What is "bloom on the target"? Thanks!

My bad, I should have clarified. When a laser hits a target in this context, the target material ablates and burns. This kicks up “dust” and other fine particulates as well as water, and this causes more bloom. It’s also a good defense against lasers of a low enough energy to exploit this, and use ablative armor that is designed to produce clouds designed to be especially opaque to the laser. You can work around this by using phased arrays and other tricks to manipulate the wavelength of the laser light in response to feedback of the target conditions. Adaptive optics are another way of combatting this issue, as well as bloom and divergence through the atmosphere.

I feel the need to point out, in light of you calling this actually existing prototype weapon "comical sci-fi", that when one googles ablative armor, one gets nothing but literal sci-fi.

Don't these hypothetical countermeasures have to assume the weapon would be effective in the first place?

Yes absolutely, the countermeasures aren’t produced because the only laser weapons deployed for the last two decades are either giant chemical lasers mounted on 747’s and designed to imtercept ICBM’s, smaller (but still quite large) ground based lasers designed to intercept rockets, or dazzling lasers that haven’t been deployed at all. The former two aren’t used against human targets and would be expensive and unwieldy if you tried. The latter don’t burn anything, they temporarily blind and disorient.

So yes, why would optical countermeasure be produced and deployed against a threat that doesn’t exist? That isn’t to say such countermeasures would be difficult to produce or deploy against a laser in this power range though.

That's great for tanks or whatever it is you have in mind but I'm not sure why you imagine this being deployed against hardened military targets. Obviously we have very different conceptions of how a weapon like this could be deployed.

YouTuber styropyro recorded a video[1] about this and wasn't at all convinced by the claims.

[1] https://youtu.be/EdURyWZD9tk

The protocol on blinding laser weapons prohibits employing or distributing weapons designed to cause blindness. Is it possible that this weapon is actually intended to be used as a blinding weapon, and the claims about its incendiary capabilities are only to obscure the intended use?

> Because the laser has been tuned to an invisible frequency, and it produces absolutely no sound, “nobody will know where the attack came from. It will look like an accident,” another researcher said. The scientists requested not to be named due to the sensitivity of the project.

OK so there's no sound where it "hits" but they didn't answer the real question I have... What does it sound like where/when the trigger is pulled?

You want it to make pew! pew! noises don’t you?

USA's 'Laser M16/M4', now almost 20 years old:

http://www.defensereview.com/352003/TIS1.pdf

One errant reflection and someone (maybe even the operator) goes blind. I hope they don't deploy these for riot control.

It’s not that long since the Chinese government ran tanks over protesters, blinding people would likely be a feature.

meta: never heard of scmp.com, but I really liked their website and flow! felt very clean. just a tad to much scroll jacking tho

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