Yes, this is for highly maneuverable soft targets.
A mirror will not work. At the power levels involved, any mirrors must be precisely tuned to the exact wavelength of the laser (e.g. dielectric mirrors) and they must be immaculately clean. That level of cleanliness is impractical in a military environment. Furthermore, the US has developed "white" laser weapons, which will defeat any tuned dielectric mirror like it wasn't there since the lasers have a broad spectrum of wavelengths.
The reflectivity can't just be good, it needs to be nearly perfect across a wide spectrum. At high power levels, even 99% reflectance isn't good enough and that won't be practically achievable for most weapons in any case.
The wiki link says otherwise. Silver and gold are <40% reflective in visible, while aluminium is ~90%, neither of that is enough. Reflectivity goes down very quickly as metals heat up.
That's true, but "reflectivity" even for a good first-surface mirror only means something like 95% energy return. That means 250W of energy being absorbed by an infinitesimally thin layer at the surface of the mirror, instantly pulling it off the glass and vaporizing it. Without assist gas to remove it in a cutting application, the cloud of plasma actually helps absorb a lot of the energy.
Nah, it’ll totally work. For one thing, you won’t be able to precisely track the spot at which energy is focused. For another, most rocket shaped targets can be made to spin (and some already do spin and rely on rotation to scan for targets), thus defeating your “directed energy” entirely. It’s a boondoggle and a waste of taxpayer money, easily defeated from a couple of miles away with a 50bmg rifle or a salvo of cheap unguided mines.
Your intuition about the properties and effects of high-power lasers is failing you. The original design targets for US military lasers several decades ago were specifically selected because there are no practical countermeasures. These design targets were ambitious; it took several decades to develop practical lasers that could start to meet them.
There are fundamental limits to material physics. Spinning doesn't help because there are always fixed points by definition. There are both materials science and engineering limits to spin rates, so you can precisely design your laser power levels to be reliably effective at the upper bound spin rates. All of this was fully modeled out and calculated half a century ago. Other countermeasures, like dielectric mirrors, would be very expensive to use on cheap weapons, and the US already developed a counter-countermeasure anyway with the invention of lasers that emit "white" light.
The scientists and engineers that did R&D on this over the last several decades weren't idiots. Everything "obvious" that armchair weapons experts might come up with were accounted for a long time ago.
I’m not an “armchair” weapons expert. I’m actually trained in weapons design (guidance systems mostly). This is a moronic waste of money and “engineers and scientists” who worked on it have no illusions whatsoever about that, I can assure you. It might be able to defeat something “Hamas grade” or a Mavic with an RPG taped to it, but it’s absolutely useless against any even remotely serious adversary or even something as pedestrian as a modern (where by “modern” I mean made in the 80s or later) wire guided ATGM, which both itself rotates and flies along a pseudorandom spiral trajectory. Try engaging that with your high energy barrel of MIC pork.
> It might be able to defeat something “Hamas grade” or a Mavic with an RPG taped to it
That alone would be a major capability for a layered defense system. Cleaning up decoys would be another one (not necessarily getting those down, IDing them due to reflectivity is almost as good).
What does any of this have to do with US weapon systems? They are way ahead of anyone else in this area of tech. They have invested a lot in these capabilities over many decades, and the public capabilities are state-of-the-art. Laser tech is an extremely difficult engineering discipline, you can’t enter it casually. The US has made large focused investments on mastering this tech in a way no one else has over many decades.
I suspect at least in part due to the difficulties with reliable tracking and ID, not the negation component. Plus due to the fact that RF is (so far) still very effective at least against cheaper stuff. But once that changes the game will be very different.
Not “drone swarm”, this laser can be easily defeated with cheap as dirt weaponry that’s been in use on the battlefield since WW1. In general anything that’s high tech and expensive makes an excellent target. Doubly so if it emits any electromagnetic radiation, and doesn’t shoot very far.
Or just something that gets smoky when it burns, then the energy is deposited entirely into the smoke boundary layer (and might even make a nice reflective plasma).
Intumescent paints are considered the lightest form of passive fire protection. An intumescent is a coating that, when exposed to heat, is rapidly transformed through sublimation, and expands many times its original thickness (up to 100 times), to form a stable, carbonaceous char.
The resultant char reduces the conduction of heat from the fire to the substrate, delaying the time it takes to reach structural failure.
I'm considering getting some for my kitchen remodel.
It would need to be a neutral-density-ish smoke, wouldn't it? If my dealings with (much, much) smaller lasers are an indication, "regular" smoke from laser-heated things is generally buoyant in air, and would tend to just float up and away from a presumably-horizontal beam. It seems like this would limit the smoke's abilities to diffuse and absorb the energy.
As I understand it defenses depend greatly on pulse duration.
Rotation dramatically increases effective armor thickness if energy is delivered over a long time frame etc. But drop to the nanosecond range and a cloud of plasma which used to be the armor is going to between the laser and what’s left of the armor. That said, you don’t need to drill through a target, a jet of ablated material means an equal and opposite force is going in the other direction.
Really though the biggest limitation of a laser defense system is pure kinetic kill weapons. Big thing moving Mach 2+ is deadly even without pinpoint accuracy or being filled with high explosives.
Yes it would ablate at some rate, based on the drag, convective buoyancy, etc. If the smoke is optically thick at all, even if it pushed away almost immediately, the wall ablation rate would probably be a couple orders of magnitude lower than if the laser hit the wall directly...
If you want a fun read, the Galileo probe wall ablation paper is fun, the re-entry power density (at the wall!) was ~10kW/cm^2.
I'd be sort of surprised if the buoyancy mattered much in the face of the amount of air something needs to move to fly. On the time frames that buoyancy acts in I imagine (without data) it's no longer around the drone anyways.
C-RAM: counter rocket, artillery & mortar. You have to be able to get into the incoming rounds, through the metal bodies of artillery shells, rocket warheads, etc.
if the payload is just ballistic and its trajectory is known, the target can just move out of its way and let it hit dirt
those things usually have some sort of heat/EM/something seeking sensor to make it accurate to the last meter, and those still can't "see" through metal (yet (that we know about))
What's their impact on drones and as UAV defence which may be a mostly static site function?
Mobility to deployment, then defended asset which in turn offers perimeter defence against unmanned subsonic directed or non ballistic weapons. (I'm guessing supersonic and ballistic bring different problems)
[Edit: I wouldn't for a minute discount the complaints from boots on the ground. Lots of amazing tech turns out to be useless in the field, has to be redeployed fit to purpose]
"The Protocol does not prohibit attacks against binoculars, periscopes, telescopes, and other optical equipment because it was unknown whether laser attacks on such devices could cause permanent blindness."
The hardest parts are still power source, bloom on target (burning stuff kicks up dust into the air and disperses the laser), and adaptive optic focusing to get through all sorts of atmospheric conditions.
It must be said that the last two are in the realm of things the US military might plausibly be decades ahead on, in secret. The power source on the other hand is far more likely to emerge from the public or academic sector.
Could be a radar or IRST-style [0] system, both are used for that kind of thing. I imagine there might be some design complications with something like IRST to the extent they have to keep laser reflections from hitting the imager.
Cool concept! Probably not that useful for most payloads though like cameras or anything similar. Unless the base where the payload is attached to, is separate from the airframe.
Mirrors are not a defense against high power lasers. The mirror is not 100% efficient, and as soon as it warps or discolors, it absorbs more energy and promptly burns through.
And yes, this is a problem for laser optics too: which is why these designs tend to use focused arrays of beams, cooling systems and/or parabolic mirrors (which also helps with divergence).
That’s correct, but it will definitely require more time, which practically speaking, you won’t have, after all the mirror is made of thin sheet of metal, which requires an extremely high temperature to melt. I think beryllium -which is used already in military- make a good choice, plus the spinning drone as mentioned above would disperse the energy, making it harder to take down.
> which requires an extremely high temperature to melt
What do you think 4kW in a square centimeter generate? Spring air?
Also, beryllium would be an odd choice because all you get is energy soaked up by ablation. No reflection whatsoever. How thick would you like to make that beryllium coating?
If you assume one millimeter (which is a pretty chunky coating), you'd need about 1/10th of a second to ablate it.
As for spinning... you do spin around an axis. And that axis is likely aligned with the direction of travel, otherwise you have interesting dynamic properties.
Which means if you aim at the nose, you can spin all you want. It's not moving. If you miss the nose a bit, oh well, it'll take maybe 2 or 3 tenths of a second. Even if you're well into hypersonic speed range, that's not enough to get the missile on target.
And drones... well, drones just limber along at speeds that make any rotations just a waste of engineering resources. You have time to heat up the whole thing. And fry an egg on it.
Look, there are issues with DE weapons. But 50 years of research mean you're not discovering them from first principles while typing a HN comment.
That’s all nice and sounds good in theory, but practically speaking, drones are always ahead. Assuming the laser is indeed effective, the drone was detected too, and the accuracy is spot on, good luck taking down a swarm that’s piloted by AI, all at the fraction of the cost compared to that defense system in place.
That's a heckin' assumption you're injecting there.
For a drone to fly a system of motors, batteries, sensors and microprocessors has to engage in a complex real-time process to maintain stability, navigate and acquire targets.
Disrupt any of that, the drone falls out of the sky. Or goes off course. Or explodes.
Punching through steel is useful when you're trying to shootdown dumb-fire artillery rounds which have to survive being fired under a 310MPa pressure and need to trigger an internal detonation.
A drone with a camera will be blinded if it catches even a glancing reflection of a 50kW laser. And every bit of defense you add to that system is now increasing cost, weight and power requirements. How quickly can the laser track and engage a drone? It's light, so the time is limited solely by optics tracking speed - for all purposes impact is instantaneous.
And the idea of "stealth" runs in direct opposition to all ideas of reflective coatings - since that does the exact opposite of what stealth materials do to defeat RADAR and LIDAR.
You're arguing from the wrong position. The cost of a defense system competes against the cost of other defense systems, and only very indirectly against the cost of the attack.
If you haven't read the article: The final paragraph addresses most costs. Prototyping the laser - which is always a bit more expensive than a productionized version - was $73 million. A single missile shot is $4 million.
That's 20 missiles shot at drones. That's it. Which means, on a pure cost basis, this thing getting off 20 shots at drones means it's paid for itself. Given it's capable of firing 6 shots per minutes, you need 4 minutes to make it worth the investment. Which, given drone speeds, probably means you fire for 2 minutes and start moving - another advantage it has over a more stationary missile systems.
Cost isn't the issue here.
As the fine article points out, the problems are of an operational nature.
Polished metal will not work at these power levels. It would need to be a dielectric mirror, which can only be tuned to be extremely reflective for a narrow range of wavelengths. The mirrors would cost more than the drone in many cases. Furthermore, the US has developed "white" lasers that don't have a specific wavelength to optimize for, they emit photons with a wide range of wavelengths specifically to defeat dielectric mirrors.
Do you really need to burn through steel plate? Seems like something like this is for shooting down cheap drones.
Though I've always wondered about laser weapons -- I'd think the obvious defense is cladding the device in a mirror surface.