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I've been reading into directed energy weapons recently, and they seem like they're going to be a gamechanger. I'm just curious as to material countermeasures. I've learnt that some dielectric mirrors can be highly reflective, but I can't see them working in a protective fashion and I imagine the range of wavelengths they could reflect would be too small/specific. The current lasers built by Raytheon are between 10-50kW, the 10 kW one being able to shoot down a consumer drone in roughly 10 seconds.

Anyone with a material science/physics background chip in on how easy/what materials could be used as a countermeasure, and how effective you could imagine them to be? I'm just interested as to what the directed energy arms race might look like in 3-5 years. To what extent would simply painting weapons/drones white increase their survivability?

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  • $\begingroup$ Chrome plating would delay the shootdown. $\endgroup$
    – mike stone
    Sep 9, 2023 at 15:39
  • $\begingroup$ Not necessarily as game changing as you might think. The best defense against lasers is the same as for artillery shells and hypersonic missiles. Don't be where they are. $\endgroup$
    – mmesser314
    Sep 9, 2023 at 15:43
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    $\begingroup$ Seems unlikely that anyone will be targeting your consumer drone, barring trying to fly it over Area 51. And then you will find that targeting the controller is pretty effective too… $\endgroup$
    – Jon Custer
    Sep 9, 2023 at 15:47

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From a materials science standpoint, there are two approaches, as follows.

First is to make the coating as reflective as possible at the wavelength of the shooter-downer beam (this is a highly technical term, used only by real hip dudes and dudettes in the shootdown business). This keeps the incident beam from getting into the vehicle being shot at. Note that there might not exist a suitable coating; x-rays and gamma rays can't be stopped in this way.

Next is to coat the object with a sacrificial coating that has a high specific heat capacity, high vaporization temperature, and low thermal conductivity. When the beam hits it, it explodes into vapor before the heat has had enough time to penetrate the coating and enter the vehicle structure. Such materials are called ablative heat shields and are used in re-entry vehicles to prevent them from being burned up. You just make them thick enough to withstand the expected duration of the heat exposure.

Now comes the fun part: for shooter-downer beams of very brief duration, as in the case of an atomic bomb blast, even a coat of ordinary car paint can serve as a one-time ablative shield. Movies from atomic bomb tests show this quite clearly: a school bus exposed to the bomb flash loses its paint in an instant, which explodes into a thick layer of soot right off the metal body of the bus before the metal has a chance to melt.

In this case, it is possible to paint the bus (or any other object, like a camera housing) with paint that is reflective in the IR/visible/UV range and then the paint will survive. This was done by experiment during US bomb testing in the 1940s and 50s.

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