4 ms·

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 wavel

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.

ein0p 2y ago
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.
- jjtheblunt 2y ago
  What if mounted on an airframe a la pave-low ?
- some_random 2y ago
  How are you going to defeat a drone swarm with a 50bmg rifle or dumb mines?
  - ein0p 2y ago
    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.
- jandrewrogers 2y ago
  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.
  - ein0p 2y 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.
    - ptero 2y ago
      > 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).
      - 2y ago
nuccy 2y ago
If target is metal coated with gold, silver or aluminium layer [1], then the reflectivity is good from UV up to far IR. 1. https://en.m.wikipedia.org/wiki/Reflectance https://en.m.wikipedia.org/wiki/Reflectance
- Pharaoh2 2y ago
  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.
- LeifCarrotson 2y ago
  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.
- jandrewrogers 2y ago
  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.

ein0p 2y ago

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.

jjtheblunt 2y ago
What if mounted on an airframe a la pave-low ?
some_random 2y ago
How are you going to defeat a drone swarm with a 50bmg rifle or dumb mines?
- ein0p 2y ago
  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.
jandrewrogers 2y ago
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.
- ein0p 2y 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.
  - ptero 2y ago
    > 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).
    - 2y ago

nuccy 2y ago

If target is metal coated with gold, silver or aluminium layer [1], then the reflectivity is good from UV up to far IR. 1. https://en.m.wikipedia.org/wiki/Reflectance https://en.m.wikipedia.org/wiki/Reflectance

Pharaoh2 2y ago
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.
LeifCarrotson 2y ago
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.
jandrewrogers 2y ago
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.