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I have seen this post:

New infrared laser weapon, the Laser Weapons System, could shoot down drones or disable ships: US Navy

You can watch the video as well. that exhibits a laser weapon which can burn a fighter aircraft.

I have two questions:

  • How does it work?
  • Is it possible to create a mirror which can reflect the laser beam back ? If so, why won't the mirror burn up as well?
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closed as off topic by dmckee Apr 11 '13 at 2:07

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are you thinking of burning up the source? –  anna v Apr 9 '13 at 14:09
    
no but how a mirror can be stable where the air craft gets burn –  0x90 Apr 9 '13 at 14:13
    
The protection could just be a polished coating all over. There will still be vulnerable parts, like wheels, windows and plastic parts that will burn though. –  anna v Apr 9 '13 at 14:15
2  
There is a flag suggesting that this is off-topic. I'm inclined to agree that "how does [complicated weapon system] work?" is pretty marginal: it's probably more about integration and systemization than about physics as such. However the secondary question about the mirror is a good one, and there may be good questions about the physical principle behind some parts of the technology. @0x90 if you could refocus the text on the mirror I would feel it should remain open. –  dmckee Apr 9 '13 at 23:41

2 Answers 2

It works by heating the object. It is a large high power laser that emits in the infrared part of the spectrum.

I guess there is a load of electronics for aiming the thing at a moving target to keep the beam localised and speed up the process.

As mentioned in the article a reflective coating on the target could work very well to mitigate the heating effects.

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LAWS is a relatively low power (kW) system and works by simply heating the target until it melts or burns, this is different to the stars-wars and aircraft mounted lasers that use MW and very high pulse energy to vapourise the target with a single shot.

This kind of weapon has a few problems:
You need to hold the beam on the target for several seconds. But there is enough absorption in the air to heat the air and change the optical properties, so the beam tends to move off target. In the tests the target was cooperatively flying across the view - allowing the beam to move into clean air.

You can lower the energy absorbed by coating the target in shiny aluminium, even exposed to air the reflectivity of Al is >85% at these bands, so only 1/6 of the energy arriving at the target will be absorbed. You can also arrange for the target to have a low angle of incidence surfaces facing the ship.

I suspect it is going to be a lot more effective against slow flying dark painted drones than a supersonic anti-ship missile with a reflective pointed nose cone, coming straight at you for 10seconds.

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