How well can laser light pulses travel through fiber optics? (I am talking about intense laser pulses such as this - not regular lasers)
Could you have larger version of this in a backpack with the gun portion being the end of a fiber optic line? Could you join multiple impulses together into a single fiber for added power?
Not my field, but I'll play with some numbers on a Friday afternoon. From some googling, I'm getting an estimate of about -1dB attenuation for the fiber optic and end connectors for a meter long fiber in the near IR. Which would give about 20% losses.
The linked-to gun said it did a 1MW pulse, so to match that with 20% losses you need to start with 1.25MW, giving you 0.25MW loss. But the video doesn't state a pulse time. You can use (http://www.mhi-inc.com/Converter/watt_calculator.htm) to play around with times... assuming it fires for 0.001s (I would guess it is shorter than that) and all that loss shows up as heat, it would be less than a BTU, so easily cool-able.
Assuming your backpack could carry enough energy to have it fire at that power level for a full second, that conversion page says the waste heat from the fiber would melt a 1.6 pound block of ice. Such a backpack would do well to have a top-loading ice reservoir.
However that loss percentage is probably for reasonably unbent fibers, and the whole point of the backpack-to-gun fiber is to allow bending quite a bit. For a higher power system, I'd think it better to skip the fiber optics and instead have something like the laser turrets they put on the front of planes (http://www.mda.mil/system/altb.html). Have a small version of that come up over the wearer's shoulder, with the turret sitting in front of the user so they can aim anywhere in front of them. Even with 8 mirrors in the path to get the business end somewhere comfortable, 98% efficient mirrors would have 15% losses.
So in thinking about this more - it seems that using a fiber relay system is less than ideal - and instead what we may want is a series of tubes with mirrors. Tubes and mirrors with joints that allow articulation of the tube system.
Further, based on the description of the plane-mounted anti-missle laser system, which uses a telescoping system to focus the beam - it would seem that we could incorporate the telescoping functions into our articulated tube,
It should be a trivial exercise to combine multiple beams via prisms and mirrors, at east a solveable problem.
So - we will need the exoskeleton I mentioned in my other post as we will need the rigidity of the system to mount our series of tubes to.
Interestingly, the .mil article refers to KW class lasers - rather than MW class.
I think some testing needs to be done with shooting this DIY laser through a telescope as well.
Transmission efficiency / meter is one of the specs that come with the base fiber. You'll want one that is most efficient in the IR band. Note that you do lose power to bends in the fiber.
All of the laser power records set over the last few years have been with lasers that combine many smaller lasers into a single beam. Not easy but its a solved problem.
Free Electron Lasers are new big thing, you can pump them with an unlicensed proton accelerator backpack :-)
I think what we need, is to couple the weight of the accelerator backpack-based laser weapon and a generator to power it with the new exoskeleton suits being built by Lockheed, Boston Robotics and others.
I have been toying with the idea of starting an O.P.E.N. project; Open Portable ExoskeletoNs... well, I guess the name needs work.
http://www.google.com/search?q=string+cut+game+prize&tbs...