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Omnidirectional retaliatory laser

 
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So, we were discussing (elsewhere) the possibility of planes having powerful lasers to retaliate against ground-borne laser pointers.

This made me wonder if such a system could not be automated. One problem is that I have only a vague understanding of how lasers work, but that needn't be a problem.

In a laser, you have a lasing medium which is "pumped" up to a high energy, such that it is ready to release that energy as light. An initial pulse then sends a light beam through it, and that beam triggers the release of more light. A half-silvered mirror bounces some of this light back (and forth again, and back) to release yet more light, whilst some of the light escapes as a laser beam.

Now, suppose we make the laser spherical. There'll be a spherical mirror in the middle, and a spherical half-silvered shell, with the lasing medium between them (a bit like the earth's mantle, between the core and the crust). An incoming laser beam should then start a cascade reaction which would produce a far more powerful beam coming out of the sphere in the same direction. Firing a laser pointer at this device would then be a bit like firing a musket into the throat of a loaded black-powder cannon, i.e. inadvisable.

MaxwellBuchanan, Dec 17 2019

Laser Pumping https://en.wikipedi.../wiki/Laser_pumping
[Voice, Dec 17 2019]

[link]






       Firstly, the thing your musket would hit would be a cannonball, which wouldn't care one way or another, followed by the interior of the cannon's barrel, which may get scratched up a bit.   

       Secondly, firing a weak laser into a pumped laser's gain medium will accomplish nothing.   

       Thirdly, a spherical medium would not provide coherent light.
Voice, Dec 17 2019
  

       //Firstly...
Secondly...
Thirdly...//

But apart from that it would work fine, right?
hippo, Dec 17 2019
  

       //the thing your musket would hit would be a cannonball// Yes, but if the cannonball has a mass of black powder behind it... Is it not the case that over-enhusiastic ramming of a black powder weapon can set it off?   

       //firing a weak laser into a pumped laser's gain medium will accomplish nothing// Are you quite sure?   

       // //Firstly... Secondly... Thirdly...// So, out of an infinite number of possible failure modes, you've only found three that apply? Statistically, that's a huge success.
MaxwellBuchanan, Dec 17 2019
  

       Not actually infinite; just very, very large.   

       We can guess where you were and what you were doing during the lecture on directed-energy weapons; or rather, we can infer with a very high confidence factor what you weren't doing, which would be "Paying any attention whatsoever to the lecture" ....   

       // a bit like firing a musket into the throat of a loaded black-powder cannon, //   

       Even at short range, that would have no effect. The ball is low velocity and made of lead. It won't be hot, and it can't strike sparks. Even for a tiny cannon like a falconet, the disproportionate mass of the musket ball to the cannon ball is such that the compressive shock transmitted to the charge (through the wad) wil be nowhere near enough to trigger deflagration.   

       Would you like to buy a better analogy ? We have a fine selection in our online store at very reasonable prices.
8th of 7, Dec 17 2019
  

       //an infinite number of possible failure modes// What are they all, please?
pocmloc, Dec 17 2019
  

       This idea may have been born wrong, but it now identifies as right.
MaxwellBuchanan, Dec 17 2019
  

       <Sigh/>   

       There's always one, isn't there ?   

       <Hurls whiteboard marker at [poc]/>   

       There you are, start writing them down so everyone can share.
8th of 7, Dec 17 2019
  

       Making deals with the Borg is like making deals with the devil, except that assimilation is more painful than anything the devil has available. Nevertheless I would like to hear the terms for one analogy.
Voice, Dec 17 2019
  

       Hay fever is pretty cheap as analogy. Don't go for the lactose intolerance though.
MaxwellBuchanan, Dec 17 2019
  

       It seems that there's always two, not just one ...
8th of 7, Dec 17 2019
  

       Hmm... combining this crazy idea with the "cube-corner reflector" crazy idea...
Keep the 2 spheres (Probably have the "inner" relatively large, say half the size of the outer) BUT coated with retroreflectors. Because we want minimal offset, use (many, many) micron scale cube corners. Thus, we get (effectively) a tiny flat/flat type laser cavity (inefficient, I know), but in any direction. The ouside of the outer sphere will need to be a "matching" shape to the cube-corners on the inside of it, to stop refractive troubles.
Power supply to the laser medium; well, if it looks just like a plasma globe, we power it like a plasma globe! Just need to find the balance between enough power for it to work, but not so much that it works by itself (ie. NEEDS the external incident beam as well).
That just leaves the problem of having the laser medium frequency matching that of the incoming beam; unlikely, but could be done just for the experimental proof-of- concept (ie. use the same medium in a "conventional" set- up as the incident beam).
neutrinos_shadow, Dec 17 2019
  

       I once met a girl called Anna Logy, but I can't remember what I metaphor.
MaxwellBuchanan, Dec 17 2019
  

       Lactose intolerance isn't an allergy, it's a (technically lack of...) genetic mutation.
neutrinos_shadow, Dec 17 2019
  

       Yeah, everyone knows that [neut], don't milk it ...
8th of 7, Dec 17 2019
  

       I'm not sure if your jokes are getting worse, or my sense of humour needs recalibrating...
neutrinos_shadow, Dec 17 2019
  

       P(1)=0.95, P(2)=0.4; P(1,2)=0.38.
MaxwellBuchanan, Dec 17 2019
  

       P(2)=0.4 gives me a glitch; 0.375 works better, but that makes P(1,2) a bit unstable... (it's been a very long time since I did statistics, so I'll just pretend I can remember what that all means).
neutrinos_shadow, Dec 17 2019
  

       It either means he falsifies scientific results or that your sense of humor need re-calibrating.
Voice, Dec 18 2019
  

       Those two options aren't mutually exclusive, [ Voice].   

       As to the terms for analogies, it depends whether you just want a DIY analogy, supply-and-fit, or the complete service including a maintenance contract.
8th of 7, Dec 18 2019
  

       Don't forget simile-as-a-service.
pertinax, Dec 18 2019
  

       What's that like, then ?
8th of 7, Dec 18 2019
  

       For this to work, the laser is to respond at meaningful power. [Voice] is right though, it wouldn't be coherrant. That doesn't matter though, lasers are mostly used as a light source that's specific in wavelength/timing/direction, rather than for all the photons being in step. Welding doesn't put out coherrent light but will happily scortch retinas.   

       What is meaningful power? Well, at night, aircraft on approach, lets say 300m. In order to make our photonic mischief maker regret his decision, we need, say, 10x sunlight to be delivered. Sunlight is say, 1kW/m2. So 10x that on a sphere 300m radius, gives us a surface area of 1ish x10^6 so we need about 10 gigawatts of light source.   

       Now, the sensible place to hang this device is underneath, meaning half the hemisphere of light will impinge upon the lower surface of the fuselage at relatively short range, say 5m2. That's around 1x10^9W/m2. That might bring up some issues with certificaiton, although it might bring the rather dashing "anti-flash white" colors back into fashion.
bs0u0155, Dec 18 2019
  

       Ah, I can see where you've gone wrong, [bs]. I don't want the whole hemisphere to light up and blind everyone on the ground - I want it to lase in the reciprocal direction to the incoming beam.
MaxwellBuchanan, Dec 18 2019
  

       //I want it to lase in the reciprocal direction to the incoming beam.//   

       pumped lasers don't inherrantly fire back down the line of the triggar, otherwise, there wouldn't be much of a triggar left in many cases. The way you have it set up, if possible, would emit spherically.   

       What you want is a detector array, some smart targeting box and a slightly larger laser.
bs0u0155, Dec 18 2019
  

       No. What I want is a ten day holiday on a sun-baked island peppered with superb restaurants, and for the UK to hit "Pause" while I'm there so I don't fall behind.
MaxwellBuchanan, Dec 18 2019
  

       //UK to hit "Pause" while I'm there so I don't fall behind.//   

       You can only fall behind if the competition is moving and moving in the right direciton. If a sudden administrative load or other distraction can be induced...
bs0u0155, Dec 18 2019
  

       // sun-baked island peppered with superb restaurants //   

       Well ... Australia's an island, and by all reports pretty sun-baked at the moment.   

       Sorry, no data on the restaurants. They use the system called "democracy" so presumably there are catering facilities so that the fat cats can ride their gravy train to eat their Big Dinners ...   

       So, try Canberra.
8th of 7, Dec 18 2019
  

       //You can only fall behind if the competition is moving and moving in the right direciton.// Well, fortunately for me the competition is stampeding en masse in a very, very unwise direction.   

       // Australia's an island// Yes but, for reasons known only (if at all) to themselves, they insist on operating about 12 hours out of sync, and have also decided to place themselves very far away, factors which make a ten-day jaunt challenging.
MaxwellBuchanan, Dec 18 2019
  

       Look, that's not a problem. We can beam you there for all practical purposes instantaneously. Besides, we're looking for a volunteer to test our transporter since we fixed it. We're almost sure that we've probably fixed most of the problems now - at least, we've completely replaced the control panel that Sturton vomited on. We kept telling him what it was, that it wouldn't accept his coins (how did he come by actual money by the way ?), and that he wouldn't win anything even if he could get three identical fruits in a row within three spins, but would he listen ? No.   

       Mind you, it was quite a shock when he hit what he claimed was the "nudge" button and that stuffed toy panda appeared on the transporter pad. There's probably some child somewhere crying its eyes out because its toy suddenly vanished.   

       So perhaps there is an upside after all.
8th of 7, Dec 18 2019
  

       Yes, but if I wanted to go to Australia, it would be for impractical purposes.
MaxwellBuchanan, Dec 18 2019
  

       //for the UK to hit "Pause" while I'm there// I thought it'd been on pause for the last three years, and someone has only now jabbed the "fast forward" button and the "eject" button at once, in a way which might just produce some badly scrunched magnetic tape.
pertinax, Dec 19 2019
  

       Even that is progress, of a sort...
8th of 7, Dec 19 2019
  

       //Those two options aren't mutually exclusive, //   

       They certainly are. The "either" modifies the clause "it means", which clearly referred to the existence of[Max]'s comment. [Max]'s comment could not both be factual (such that [neutrinos]'s sense of humor needs to be adjusted) AND that Max indulges in scientific shenanigans.
Voice, Dec 20 2019
  

       We disagree, in that while your statement is grammatically correct in implying exclusivity, it is predicated on incorrect facts, in that [Max] is proven to be an unprincipled and blatant purveyor of porkie pies, and [neut] has the sense of humour of a 19th century scotch presbyterian lay preacher with toothache.   

       <later>   

       Actually, there's prior art for [MB]'s original idea- the Corbomite device...
8th of 7, Dec 20 2019
  
      
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