
Military Laser Hits Battlefield Strength - chaostheory
http://blog.wired.com/defense/2009/03/military-laser.html
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electromagnetic
So this uses 150 kilowatts of energy, or basically the equivalent of the
gunpowder in 3 .50 cal bullets. Wouldn't the more practical solution be to
invent an extremely accurate like .70 cal bullet controlled by the same
targeting system.

A .50 cal rifle can target accurately at near 2km, and has a useful range of
7km. Heavy mortars (IE two-man military or truck towed, not the ones the
terrorists are using) usually only reach 8km in range and the high trajectory
and slow velocity probably make it exceptionally easy to target (compared to
conventional supersonic artillery rounds).

So I ask, wouldn't the simplest solution have been a highly accurate heavy
caliber rifle with explosive rounds that can hit a mortar shell at the peak of
its arc when it's moving the slowest. The high refire rate already achieved
with naval defensive weapons would mean you could take a few dozen shots and
account for any inherent inaccuracy in an explosion propelled projectile.

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blackguardx
The difference is that a laser applies nearly 100% of its energy to the target
(the rest being lost to atmospheric effects). A bullet loses energy quickly as
it travels through the atmosphere.

A laser also travels "at the speed of light," making targeting much simpler.

A laser also travels in a straight line. A bullet is affected by gravity and
wind, all of deflect it from its path and must be accounted for.

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electromagnetic
Hah, read up on the Navy's railgun tests. They're expecting accuracy of 5
meters at 370km's.

A bullet loses _no_ energy to gravity, it just gets converted into potential
energy. It also loses little energy to the atmosphere, it retains about 90% to
impact.

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blackguardx
I didn't say a bullet loses energy to gravity. I said it affects the flight
path.

And if you think beyond high school physics for a second, you will realize
that gravity does take away energy away from the collision if the target is at
a higher elevation than the gun. The potential energy is useless in that
situation. All that matters is kinetic energy.

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jodrellblank
What is it about LASERs that make them so useful in so many domains?

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chaosmachine
they're a readily available source of coherent, monochromatic, collimated
light.

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jodrellblank
But why is that so good for telecoms signalling, precise cutting, spaceship
propulsion, measurement, teleportation experiments, holding parts of highly
accurate subatomic clocks, tripwire systems, optical media drives, igniting
fusion reactions, pointers and targetting systems, interferometry, eye
surgery, 3d scanners..

They are like many fundamental building block componenta in one.

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derefr
To answer your question more bluntly: they are energy waves, and [or thus]
they move quickly.

All of these things could be done materially (signalling with sound waves in
air, record players instead of optical media, pointing with a physical
pointer, etc.) but coherent light can be moved around much more quickly, due
firstly to the speed of light, but also due to the wave properties of
reflection, refraction and diffraction. And, despite this ease of targeting,
you can "load" as much, or as little, energy into the stream as you wish,
because photons have negligible mass. Finally, the "coherent" part means that
you actually get to keep these advantages over a distance, instead of having
them stolen by the power law.

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froo
I spent a little while considering whether or not to post in this thread, but
here goes....

All we need now is to figure out how to attach these frikkin' lasers to some
sharks.

