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Navy Planning To Build Laser Cannon In Four Years

Posted by samzenpus on from the sea-the-future dept.

CowboyRobot writes "The US Navy is months away from requesting bids from contractors to construct a laser weapon for its ships, now that the technology is feasible. 'The key point came last April, when the Navy put a test laser firing a (relatively weak) 15-kilowatt beam aboard a decommissioned destroyer... the Martime Laser Demonstrator cut through choppy California waters, an overcast sky and salty sea air to burn through the outboard engine of a moving motorboat a mile away.'"

2 of 195 comments (clear)

  1. Too easy to defend against this by joe_frisch · · Score: 5, Informative

    If the attacking boat has a corner cube reflector there is a good chance of blinding people on the defending ship. Since the system needs to be ready for use without warning, the crew would need to always wear laser goggles.

    You can protect a missile with an ablative shield - the sort used for re-entry vehicles. This doesn't need to be high tech - wood works surprisingly well (used by the Chinese for spacecraft years ago).

    You could use a more diffuse beam to blind the crew of an attacking boat, but I think that violates the Geneva convention.

    I'm also very skeptical about the 1MW -> 20' of steel / second. At a kilometer away, you probably have a spot size of around a centimeter. (it depends on wavelength, optics, etc, but that is the right ball park. Iron vaporization energy is 300KJ/mole or about 6KJ/gm. A 1cm long by 10M piece of iron is 1000 cc's or ~10^4 grams. So that's 60MJ to vaporize, or a minute, not a second to burn through. Of course the plume of iron vapor will disrupt the incoming beam so it will take a lot longer. This also assumes you can keep the beam perfectly focused.

    The is also the question of whether a complex device like an FEL can be kept always ready to fire within a second. The light is much faster, but its not clear that when you include the time to ready and aim the weapon that the time to hit the target is faster than for a high speed gun.

  2. Re:Hmm by Anonymous Coward · · Score: 5, Informative

    High power lasers will smoke a typical mirror. There are reflective surfaces that could work, but you have to keep them perfectly clean. Not happening at sea for long... However, a laser will be easier to track back than a tracer round...

    Maybe, maybe not.

    If the laser light doesn't scatter much, the only one who can track it back to its source is the target.

    But only AFTER getting blasted.

    Of course, you could look out for the fricken' shark in the first place... ;-)