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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.
Laser Pumping
https://en.wikipedi.../wiki/Laser_pumping
[Voice, Dec 17 2019]
[link]
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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. |
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Secondly, firing a weak laser into a pumped laser's gain medium will accomplish nothing. |
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Thirdly, a spherical medium would not provide coherent light. |
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//Firstly...
Secondly...
Thirdly...//
But apart from that
it would work fine, right? |
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//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? |
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//firing a weak laser into a pumped laser's gain medium will
accomplish nothing// Are you quite sure? |
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// //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. |
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Not actually infinite; just very, very large. |
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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" .... |
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// a bit like firing a musket into the throat of a loaded black-powder cannon, // |
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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. |
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Would you like to buy a better analogy ? We have a fine selection in our online store at very reasonable prices. |
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//an infinite number of possible failure modes// What are they all, please? |
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This idea may have been born wrong, but it now identifies as
right. |
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There's always one, isn't there ? |
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<Hurls whiteboard marker at [poc]/> |
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There you are, start writing them down so everyone can share. |
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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. |
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Hay fever is pretty cheap as analogy. Don't go for the lactose
intolerance though. |
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It seems that there's always two, not just one ... |
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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). |
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I once met a girl called Anna Logy, but I can't remember what
I metaphor. |
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Lactose intolerance isn't an allergy, it's a (technically lack
of...) genetic mutation. |
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Yeah, everyone knows that [neut], don't milk it ... |
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I'm not sure if your jokes are getting worse, or my sense of
humour needs recalibrating... |
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P(1)=0.95, P(2)=0.4; P(1,2)=0.38. |
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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). |
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It either means he falsifies scientific results or that your
sense of humor need re-calibrating. |
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Those two options aren't mutually exclusive, [ Voice]. |
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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. |
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Don't forget simile-as-a-service. |
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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. |
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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. |
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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. |
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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. |
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//I want it to lase in the reciprocal direction to the
incoming beam.// |
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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. |
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What you want is a detector array, some smart targeting box
and a slightly larger laser. |
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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. |
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//UK to hit "Pause" while I'm there so I don't fall behind.// |
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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... |
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// sun-baked island peppered with superb restaurants // |
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Well ... Australia's an island, and by all reports pretty sun-baked at the moment. |
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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 ... |
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//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. |
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// 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. |
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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. |
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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. |
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So perhaps there is an upside after all. |
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Yes, but if I wanted to go to Australia, it would be for
impractical purposes. |
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//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. |
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Even that is progress, of a sort... |
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//Those two options aren't mutually exclusive, // |
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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. |
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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. |
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Actually, there's prior art for [MB]'s original idea- the Corbomite device... |
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