OT: Upper limit on Lasers, range and power....

[Dizzy]

Something I posted over at the dynaverse, a trek site where I hang most the time: Dynaverse Link What do u guys think of this?

I read where the US military is about to field small fighter size lasers able to destroy enemy aircraft in the blink of an eye: http://www.globalsecurity.org/org/ne...020-laser1.htm

But does size matter? Lets go to the other end of the spectrum... How big can you make one? Granted, the above laser is chemical, as is the one Boeing is mounting on their 747's to shoot down ICBM's called The Airborne Laser: Airborne Laser but to go really LARGE you'd probably need to go with an energy based device like the laser at the National Ignition Facility: http://www.llnl.gov/nif/project/index.html Animation: http://www.llnl.gov/nif/project/anim_beamline_lg.html

But that, I think, is an energy based laser. So how big (powerful in terms of terawatts and length of time the beam can operate) and how far can they shoot? Is energy consumption an issue? If you built a nuclear power plant and sat it next to a laser built larger than something say, the Giant Megellan Telescope: http://www.gmto.org/ would it be possible to use it to shoot down an ICBM and or multiple rentry warheads if tracking them and keeping them in the crosshairs isnt an issue?

And my last question would be what happens if you take a powerful laser and bounce it off a mirror in outerspace? Will a powerful laser beam even bounce off a mirror? Or will it vaporize the mirror? I can imagine, if it can be bounced and the beam remain powerful enough, a laser beam can be shot from one side of the planet and vaporize a target on the other side of the globe in under a second...

So who knows lasers?

[Will]

Well, a laser is just light. It is, in fact, an acronym for Light Amplified by Stimulated Emission of Radiation. Basically, you apply some energy to some kind of material, and you get it to emit light in a specific direction. Normally, light will move out in a radial pattern, but lasers move in a very close approximation to linear. You could aim a laser at some point, and the radius of the dot would increase by something extremely slight like 1cm/light-year (the exact amount would depend on the kind of laser, and any refraction along the way).

The power of a laser is kind of like the power of using a magnifying glass to focus sunlight, only without the need to focus. If a laser hits a mirror, what happens depends on the percentage of light that the mirror reflects; there is no perfect mirror, there is always at least a little absorption or scattering or transmitting. If the mirror reflects 99% of the light energy, and absorbs 1%, and it takes X joules to vaporize the mirror material, then the laser would need to be 100*X joules to not be reflected. And, of course, materials have different absorption/reflection/transmission/scattering properties based on frequency. So you could have armor that would handle Y joules of energy from a green laser, but would vaporize with the same energy microwave laser.

[Phoenix-D]

Speaking of wavelengths, shorter-wavelength lasers tend to be more damaging. A radio "laser" has a very broad beam, which spreads the energy in the beam out. A gamma-ray 'laser' has an extremely tiny beam, concentrating the energy.

[Renegade 13]

Theoretically, there should be no limit to the range of a laser or the power of the beam. Practically, if the range is too long, light speed limitations would impose a great difficulty for use as a weapon. Also there'd be a practical limit on power of laser, depending on the materials you're using and the power source you have available.

[NullAshton]

You could bounce a laser off a mirror in space. Maybe use multiple beams, that are focused at the time the laser bounces off the satellite. But I believe there's a treaty banning any sort of space weapons.

As for the shooting down ICBMs or multiple warheads with a laser, I don't think it's that hard. You don't even need a very powerful laser, you just need to vaporize the trigger and no more detonation.

Large lasers are hard to make, because I believe there's a limit on just how much energy you can channel because of inefficiencies. The powerful laser beam goes though the laser, and the laser melts. So much for blowing something up with that laser.

[Dizzy]

the no weapons in space thing... where is that written? I'd like to take a look. The Bush Administration hs been pretty crafty at getting around obstacles to get what it wants. If they wanted to put a 'reflecting' mirror into space, I dont think they'd call it a weapon. The laser would be the weapon and its on land.

Besides, when has the NSA ever gone in front of the 'whoever wrote and regulates the no weapons in space rule' and disclaimed what the role of the satellite was they were launching into space?

[Will]

IIRC, lasers used to "shoot down" ICBMs do nothing of the sort of vaporizing anything. What they do is interfere with the tracking and guidance systems, and essentially force it to dive down into the ocean where it would be relatively harmless.

[capnq]

Dizzy said: the no weapons in space thing... where is that written?

Outer Space Treaty

[Dizzy]

Thanks for that link!

So here's all it seems to say: "States shall not place nuclear weapons or other weapons of mass destruction in orbit or on celestial bodies or station them in outer space in any other manner; ".

That kinda opens it up for the possibility to stick up there a 'telescope refocusing lens' for 'looking around spy stuff'. I mean... the laser is on land. That satellite is just a buncha mirrors and lenses. No weapon there...

::whistles innocently::

[Renegade 13]

As soon as a country has the practical capability and reason to do so, they'll disregard that treaty right away. After all, who's going to enforce it?

Space will be militarized eventually, it's just a matter of when and who does it first.