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Solar cutting torch
Ok, so tackling parabolic solar reflectors as my first foray into math in thirty years wasn't such a good idea. | |
I've got this idea, and it works in my head so I think it will work out here with the right materials but I can almost guarantee that your guess, (yes, yours) will be better than mine as to whether my mental projector is still functioning.
To start with I need a huge perfect parabolic dish and not
a Scheffler reflector because we want a circular convergence.
The temperature I want to reach is around 2000 degrees because all the silicates are molten at about 1200°C and I need a lot of room for error since I will be modifying the dish and none of the surfaces will be 100% reflective so we're going with overkill to ensure that the melting point of rock will be reached.
I'm guessing something like a 30 ft. diameter dish will do the trick but if that is wrong then scale it up to whatever size reaches 2000 degrees.
Now I want to cut a perfect circle at the very bottom of the dish and replace it with an inverted flat mirror on a slider track.
This will have the negative effect of decreasing the potential generated heat by the size of the parabola cut away, but all of the converging rays can now be directed downwards and the set of the slider will determine heat at the focal point because distance from bottom will determine how many rays get reflected away from the upper focal point.
Here's where I don't know if I'm right or not;
If these converging rays were to intersect within a perfectly mirrored tube, would they converge again at a distance as far from the original focal point as the length of the tube?
Also, If the tube were flexible while retaining reflectivity would the curves inside of the tube cancel out over distance so that the end convergence is always that same circular shape?
If both of those things work the way they work in my head then hand-held solar cutting torches would be a pretty cool thing, but what I would really like to see is the end of that flexible tube mirror attached to an X Y Z axis to create a backyard solar CNC machine.
I'm thinking like obsidian hot tubs carved from bed-rock and solid rock cap-stones on rtaining walls and such.
Solar powered laser
https://www.technol...olar-powered-laser/
It's crazy, but it works. [neutrinos_shadow, May 30 2018]
Magnesium Combustion Engine
Magnesium_20Energy_20Cycle
No need for solar-powered lasers. [Wrongfellow, May 30 2018]
Solar sinter project
https://www.youtube...watch?v=ptUj8JRAYu8
you want.. kind of the opposite of this? [Loris, Jun 04 2018]
Pillow fight
https://en.wikipedi...ttle_of_Fort_Pillow
"Fort Pillow marked one of the bleakest, saddest events of American military history." [8th of 7, Jun 07 2018]
For a more practical alternative, hook this up to a solar panel
https://www.youtube...watch?v=E3YCACZQ72Q
Handheld laser rifle with air assist for nuclear decommissioning [notexactly, Jun 08 2018]
[link]
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This sounds a bit like a Cassegrain telescope. |
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The central mirror needs to be curved, not flat, otherwise the incident
light will reflect off at an angle, hit the main parabola, and bounce
back towards the sun. |
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The "perfectly mirrored tube" sounds like some kind of optical fibre -
I'm not sure how much power they can handle. |
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Yes, this is a reflecting telescope with an optical fibre.
Unfortunately, though, the only way to get coherent light out
of an optical fibre is to put coherent light in. The etendue of
the light will be conserved. |
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[Wf] W. The beam from a parabola forms a cone. Put a mirror not quite halfway up the cone and it's like lopping off the top and turning it upside down, ie: it will focus on the other side of the hole cut in the bottom... big mirror though. |
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// obsidian hot tubs carved from bed-rock and solid rock cap-stones on rtaining walls and such. // |
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Ignoring the misspelling of "retaining", we consider it would be useful to draw your attention to the relevant physical properties of silicate minerals. |
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You have no doubt observed that those who perform precision work with stone generally eschew the use of heat in favour of mechanical devices, which employ either impact, abrasion, or a mixture of the two.
Unlike metals, when a point source of heat is applied to rock, it tends to spall and shatter. This is a consequence of (a) thermal conductivity and (b) coefficient of expansion. |
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Rock can indeed be converted from a solid to a liquid, but it is usually necessary to heat the entire mass, very slowly and evenly, until the melting point is reached. Failure to do so can mean it all suddenly becomes very loud and expensive. |
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Granite, an igneous rock, can be melted and re-cast, but for reasons of practicality it is far more common to work the cold crystalline solid into the desired shape and accept a high proportion of wastage. |
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With [MaxwellBuchanan] mentioning coherent light, I thought: why not make it a solar-pumped laser? See linky. |
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From the link: "A new kind of efficient, solar-powered laser has been
developed by researchers at the Tokyo Institute of Technology, in
Japan. They hope to use the laser to help them realize their goal of
developing a magnesium combustion engine." |
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Didn't we do that one here? Ah, yes... [link] |
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//hand-held solar cutting torches would be a pretty cool
thing,// |
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It would! and I think it's feasible. For reference an oxy
acetlyene cutting torch seems to be about 3-4kW. Can we
deliver that much light to a few square mm at the end of
a torch-like tool? I think so. |
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Your parabolic reflector at 30ft should give you about
109kW if you believe figures on solar radiation being
1.4kW/m2. That is, of course, subject to modification.
You either don't want or can't use about 1kW of that. UV
tends to destroy things and IR covers a very wide range of
wavelengths which don't like doing what they're told. So
you really get about 38kW. |
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Shave 20% for a cheap, non perfectly shaped mirror. Then
what you want is a collimator. That gives you nice
parallel light. What you then need is a liquid light guide,
which is just the job for broad spectrum high power
applications. I put 300W down a 5mm one. Let's assume
you can get 10x that through, which gives a 20mm guide
which will be about 80% efficient. Now you have 24kW of
colimated light coming out of your light guide and
presumably a fan or something to get rid of that 6kW
waste heat. |
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Throw a lens on it and you have more than enough raw
power coming out the end. The problem becomes what
you're aiming it at. You can see rock, which means it
reflects visible light. How much power you can actually
deliver into the surface is very much going to depend on
the material. Rock is going to be a nightmare, before you
know it your sun-torch hits a quartz crystal and a 14kW
reflection blinds poor Jim's good eye. Switching it on and
off is practically impossible, any shutter at the work end
would have to either absorb (and melt) or reflect (melt
the light guide). |
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There would be no safe way to work with the thing, or
even be in the room. Unless it was cloudy, or night, or
early/late/eclipsy. |
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It seems to me you can switch it off by steering the main reflector
away from the sun. It might not be that quick, but at least you don't
have to deal with dumping all that energy into some kind of dummy
load. |
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Just tip the reflector at the focus, like a heliograph. |
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// parabolic reflector at 30ft should give you about 109kW // |
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//Only during the day ...// |
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//Cassegrain telescopes// are cool. An inversion reflected from an outversion is a flatversion. |
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//Etendue// is a good word, but what's with the French? It should be anti-ombre. |
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//when a point source of heat is applied to rock, it tends to spall and shatter. This is a consequence of (a) thermal conductivity and (b) coefficient of expansion.// |
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I don't mind polishing rock smooth, I wanted a way to purposely cause little micro-explosions so that very rough forms are cored. I work with stone a lot and I see something like this carving thin deep ridges which can be easily chipped away saving thousands of dollars in diamond wheels.
Obsidian might have been a stretch. |
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//Switching it on and off is practically impossible, any shutter at the work end would have to either absorb (and melt) or reflect (melt the light guide).
There would be no safe way to work with the thing, or even be in the room. Unless it was cloudy, or night, or early/late/eclipsy.// |
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The temperature at the end of the optic cable could become ambient in less than one second by rapidly sliding the flat mirror towards the base... no more reflected light, no more heat. |
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The laser weapons being developed by various militaries use
pulsed,
rather than continuous, beams. |
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Would this be better at rock-drilling if you added some kind of
mirrored
fan, just inside the inner reflector, which rotates at high speed,
alternately reflecting and admitting the light, to create a high speed
pulsing effect? |
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Or perhaps spinning the inner reflector on an axis that's
perpendicular to the axis of the outer parabola? |
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I'm thinking the bed has the 6 axis gubbins, and the cutter has the constant solar track. [+]. |
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Hopefully, the future will use increased population to extrapolate knowledge and computing to reduce this to a pen. |
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A pen with a 30ft parabolic dish on one end of it? |
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Isn't there a curved steel&glass building in London that routinely parboils anybody parked in a particular spot across the road ? |
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There was … the "Walkie-talkie". It's fixed now (allegedly). |
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//it's fixed now// could be "fixed" for $10 ; just put up a "solar car recharge station" sign. |
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// British Hostile Architecture, perhaps even get some of our buildings classed as weapons. // |
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Heathrow ? The only so-called international air terminal whos mission statement is "You'll Never Leave" ... |
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// If these converging rays were to intersect within a perfectly mirrored
tube, would they converge again at a distance as far from the original focal
point as the length of the tube? // |
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The rays converge from different angles, because they come from different
heights on the paraboloid. Therefore, they will also diverge at different
angles, and therefore strike the tube wall at different distances from the
focus. This, combined with the different angles, means the second focus will
be spread out along the axis of the tube, and this will only get worse with
more reflections. |
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// Can we deliver that much light to a few square mm at the end of a torch-
like tool? I think so. // |
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Due to the above, the best you can get is by holding the end of the tube
directly against your workpiece so that the rays at least don't have a chance
to diverge after exiting the tube. This will mean that your hotspot is as wide
as the tube. Making the tube tapered will only make it worse; the angled
walls will result in the light gradually being reversed. |
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This is also dictated by the laws of etendue, which, while seeming at first to
be counterintuitive, are derived simply from the laws of thermodynamics,
which are very intuitive. |
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// Then what you want is a collimator. That gives you nice parallel light. // |
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Yes. I guess that approach might work, as long as you don't try to make a
universal collimator (which is illegal by the same laws). You could, I think,
take the focused light from the paraboloid and feed it into a properly
designed collimator, which would make the rays parallel. Then you could
focus that beam down to a point at the head. |
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However, it will probably have to be a beam as wide as the paraboloid, by
those same laws of etendue. This means that the paraboloid and collimator
would be redundant, because sunlight is already parallel! |
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<instant gut reaction> //sunlight is already parallel!//</instant gut reaction> Coming parallel of and through the surface reactions of the sun ? |
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What? It's parallel because the sun is so far away. The
difference between 93 million miles and infinity is
negligible, at least as far as angles are concerned. |
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//This is also dictated by the laws of etendue, which, while
seeming at first to be counterintuitive, are derived simply
from the laws of thermodynamics, which are very intuitive.// |
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That's what I was getting at earlier. I'm not convinced that
this is optically feasible. |
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It just needs, as [Wrongfellow] eluded, a the large area array of reflective mirrors concentrating light on the huge perfect parabolic dish. |
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It'd work ; I'm not sure the word "practical" would come into play, though. |
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A parabola focusing onto a curved plate which focuses the light collimated through the hole (so at this point you have a "white laser"(ish) arrangement), into the articulating mechanism, hanging off the bottom. |
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That worthy chunk of optics is an articulable arm, at the back of which is a flat mirror which bends at half the angle of the arm. So now you have a white laser beam that comes through the hole, bounces off the mirror and shoots through the axis of the arm, and will remain on axis - no mirror-tube needed. |
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Feel free to put another mini parabola on the end, like the first one, except use a flat mirror in order to get a point focus on the other side of its hole. |
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Nope. There are some things you can't do with light - it's all
to do (as both I and [notextactly] have mentioned) to do
with etendue. I can't claim to understand the optics in
detail, but I had a similar issue a while ago where I wanted
to concentrate light to a point. In the end, I asked Brad
Amos who knows a lot about optics - he's the guy who
invented the first working confocal microscope, and now
has his own company designing and manufacturing
microscopes - so he really, really knows. |
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You can concentrate sunlight down to an extent, but not
indefinitely; and trying to collimate after concentrating it
doesn't work. |
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If you want to use sunlight to melt rock, I'd suggest the way
to do it is to have an array of solar cells rather than a
parabolic dish, and use them to power a regular laser. That
way, you get the controllability of a laser; you can choose
the wavelength that works best for rock; you can turn it on
and off at will; you don't have to track the sun very closely;
and you can control the power; and you can get all your
heat in a small spot. I'm not seeing the advantages of a big
sunlight-concentrator over this, even if it would work. |
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//buy a laser// well, duh, though I don't imagine they're cheap at the "melts rock" power level. |
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Much less sq.m'age taken up then that of 20%-max efficiency solar cells, into a what, 10(?)% efficiency laser. |
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"etendue is conserved as light travels through free space and at refractions or reflections" - ex Wikipedia |
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Wonder if a 3D printer would produce a fine enough result, as sections of the primary and secondary mirrors, to be covered with aluminum foil. |
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// I don't imagine they're cheap at the "melts rock" energy
level. // |
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Well, Alibaba will get you a 10wK bare-bones laser for
(amazingly) about $2000. You may think that $2000 is not
cheap, but it does have the advantage that it will actually
work. |
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I am pretty sure you can't focus the sun's energy to a useful
spot on the end of flexible light guide. If you could, it
would cost you lot more in high-spec optical components
than a laser. |
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What about the other way, like an insect eye. 10,000 high temperature fibre optic cables (500mm light disc), each gathering light with a little parabolic flower, all aligned to the needed spot. A very Lexx thought. |
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// 10,000 high temperature fibre optic cables (500mm light
disc), each gathering light with a little parabolic flower, all
aligned to the needed spot. // |
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Are you suggesting tapered fibers? If so, refer to what I said
earlier about tapered tubes. |
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Not sure how this is very different from the solar arrays used for power generation. These concentrate solar energy on a crucible with salt or lithium in and this molten material is then pumped through some system which gets useful energy out of it. |
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I think the difference here is that the light is supposedly
carried by a light-guide to the melting tool. |
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But why mess about with light-guides? Big solar arrays focus hundreds of mirrors onto a point, supplying sufficient energy to melt salt. It's much more straightforward and foolproof to do it this way and, if you need to do anything more complicated like using it as a cutting tool, just move the target to the
highly-concentrated energy point, rather than vice versa. |
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That is a not unreasonable point. I think the attraction was in
having a tool you could wield. |
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Ah yes, and it is, of course more attractive to wield big powerful tools rather than the target on which those tools act. This is a metaphor undoubtedly explored in tedious, boring detail in a million unread post-modern feminism/gender studies PhD theses. |
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I've linked to an artist who used a big lens and sand to make a 3d printer. Maybe you could turn it on its side and melt it out instead? |
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The light flowers were to bounce as much light into the tubes. That sinter printer project was a great culmination of technology for art. |
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Isn't a pen just a remote joy stick, differently held? Then again, no one wants to do the tedious colouring in. |
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Well now my head hurts... but in a good way. |
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// No.
The rays converge from different angles, because they come from different heights on the paraboloid. Therefore, they will also diverge at different angles, and therefore strike the tube wall at different distances from the focus. This, combined with the different angles, means the second focus will be spread out along the axis of the tube, and this will only get worse with more reflections.// |
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The tube thing maybe not working I can understand, but I still bet that given perfectly symmetrical materials the light would re-converge at a point small enough to do the job.
I see the light rays creating circular back-to-back cone shapes down the tube where in-between each reflection-cone they refocus at points. Bends in the tube should cancel out as long as they emerge from a straight section. In fact it should be possible to minimize distortion by creating the inner tube from facets rather than round... triangular would work well and allow for twists as well... in my head anyway. |
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Like I've said, it shows me things when I zone-out and I never really know if what I'm seeing will work out here in reality.
The whole hand-held power-wand isn't Freudian in the least. |
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I was daydreaming about how it might have been possible to create those stone walls in Peru using technology that would have been available then, (no $2000.00 lasers).
I figured that they might have been able to build almost perfect parabolic reflectors by keeping pools of wet mud constantly spinning and then, as they dried, they would naturally assume that shape. Line them with flakes of Mica or another highly reflective mineral and you've got a couple of thousand cave-man degrees of seriously potent Juju.
Adding a flat reflector would allow for roughly shaping rocks using existing sections of wall as a template by bouncing enough light downwards.
Flip the new rock over and it falls right into place so tight you can't wedge a knife-blade between them.
The tube part wouldn't have been a thing then but I can more easily imagine hundreds of men rolling massive dishes back and forth all day carving rock walls into shapes that we can't figure out how to create without lasers than I can imagine them meticulously chiseling them as close to perfect as they are. |
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Moving rocks around under a stationary point of light is hard, moving a dish on rollers would be relatively easy. |
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See... I wonder things like; how was the first parabolic reflector discovered. (and I'm not talking about 17th century Yada-yada dude who wrote it down first no, the "real" first dude)
They had knowledge of parabolic reflectors thousands of years before the math for them by following nature, like that curve a long hanging rope assumes which is the basis for all ancient arches and such.
Well... I bet the "first" guy to discover this phenomenon was playing near a back eddy in a pool of water which at certain times of the day would focus enough light to light a bundle of dry grass on fire as if by magic. |
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Like... Merlin's teacher was probably just the first dude to figure out that his farts were flammable and he could keep them in a sheep-stomach bladder under his armpit and re-light them later to make fire-balls. Early science. |
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You ever wonder who was first and try to jump into their shoes?
First fire?
First garden?
First button?
First alcohol?
First sail?
First nail?
First splint?
First... whatever? It's a fun game. |
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No, no.
No more stories now. The Excalibur tale can wait for another time.
We've a big day ahead of us tomorrow and you all need your beauty-sleep.
Everyone's got their teeth brushed? Ok then way y'go now. |
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Regrettably, too late ... <link>. |
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//how it might have been possible to create those stone
walls
in Peru using technology that would have been available
then// The only information I can find on "stone walls in
Peru" shows walls made of individual stones, rather than
fused
stone. |
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If you mean "how did they get the rocks to fit so perfectly",
there was a documentary a few years ago where they
showed how it can easily be done. If I recall correctly, the
method is: |
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(1) Cut the rocks roughly to shape in the usual way. |
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(2) Put one rock on top of the other, with a banana leaf in
between. |
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(3) Lift the top rock off. Where the rocks are stained with
green juice from the banana leaf, those are the high points.
Bash those bits with another rock. |
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(4) When the green stain is more or less uniform, the rocks
are fitted perfectly to within about 50 microns tolerance. |
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The point about the Peruvians is not that they were smart
enough to invent a parabolic solar rock-melting laser. The
point is that they were smart enough to shape rocks to
within 50 microns using a banana leaf. |
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^ Yeah... I don't buy that. You see the size of some of those rocks?
They didn't lift them over and over again.
That's crazy. I would have made my bosses lots of money back then.
Not so much now... |
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//pillow fights//
///Regrettably, too late ... <link>./// |
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Well that's just a friggin downer Billy.
Keep it up and I'll tell you how I became the Iberostar Hotel wet-pillow-fight on a surfboard champion... |
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Turns out that small and fast beats large and top-heavy when the floor is moving. |
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Alright no more stories!
Don't make me come up there. |
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//You see the size of some of those rocks?
They didn't lift them over and over again//
Lifting big rocks is not so hard - for this, you only have to lift them at one end which is simple to do with a big enough lever, chock them, knock off the high-spots identified with the banana leaf, and then do the same with the other end. |
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//That's crazy. // But the idea that they had some sort of
30ft parabolic solar concentrator to melt rocks which they
wiggled around at the focal point (and which, in itself,
would not be very useful in fitting rocks together) isn't?
There's also the fact that, as [8th] pointed out really quite
some time ago, focussing intense heat onto a large rock will
just split it in an exciting but often not useful way. Then
again, there's also the fact that the surfaces of the closely-
fitting rocks show plenty of tool marks from pounding, yet
somehow lack that glassy once-melted look. |
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It's a bit like all the fruitloops who decided that
extraterrestrials must have built the pyramids, because the
fruitloops themselves couldn't figure out how to move big
rocks. It turns out that the answer to moving big rocks is
not to ask fruitloops to do it. Well, that and having huge
amounts of cheap labour. |
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// extraterrestrials must have built the pyramids // |
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We only did the bottom layer. We laid out a nice square level base for them. Look, we said, there you are. See our Cube over there ? You just keep building up the layers of blocks until you have a nice cubic structure just like that. It's easy. You have the ground plan. Just keep adding layers. You can't go wrong, it's SO simple. |
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And did they listen ? No, they didn't. The lazy sods just heaped stuff up and made an ugly triangular pile. |
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// focussing intense heat onto a large rock will just split it in an exciting but often not useful way. Then again, there's also the fact that the surfaces of the closely- fitting rocks show plenty of tool marks from pounding, yet somehow lack that glassy once-melted look.// |
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The melting/micro explosions would carve ony rough shapes. finishing would be by hand... maybe using leaves at that stage. |
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//It's a bit like all the fruitloops who decided that extraterrestrials must have built the pyramids, because the fruitloops themselves couldn't figure out how to move big rocks.// |
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You should probably throw in a few more 'you don't want to be like those guys do ya?' fruitloop references for effect. |
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I saw a thing in my head.
I relayed the thing I saw in my head.
I conveyed the pathway that led to the thing in I saw in my head. |
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...and I grow weary of being compared to others in order to fit some sort of category you seem to insist I must fit in 'your' head.
I've never met anybody like me and I bet you haven't either.
So Why should I allow myself to be labelled by you or anyone else? |
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The labels are for my own convenience. And no, you don't
want to be like those guys, do ya? |
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So... I try to figure out how regular folks could have done a thing and I am instantly lumped in with Alien-huggers huh? |
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Notice how nobody ever adds "why" one wouldn't want to be like those guys? |
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If you're asking me whether I think that aliens have interacted with humans, then yes.
I think that the American public was scheduled to be informed and that a little test was in order to determine possible reaction to the news.
After the unfortunate response to the War Of The Worlds radio fiasco it was then decided that waiting and indoctrination would be a better idea. |
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Ever notice how ancient Sumerian writings never made it into history class even though they are the oldest writings ever found?
Whether they are factual or not is irrelevant. That they were purposely not taught makes me wonder just how much else is purposely not taught. |
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aaaaanyway... I was talking with a satellite dish installation guy and he said that the older larger dishes are pretty easy to come by now so I think I'm going to cobble together a small-ish version of this when I get settled again.
I might try the primitive version as well. There's this rapid-setting self-leveler that cures in one hour and I like the idea of being able to determine focal point length by the rate of spin.
hmmm I wonder how cheaply I can get my hands on a chunk of Mica. |
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...Ooh, or Galena. Galena would be good. |
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Oh, just the American public, then? Still, I guess that would
make sense. The aliens probably came looking for sasquatch. |
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Also, I'm a little disappointed in your education system over
there. You mean they didn't cover the Enmerkar legends,
Gilgamesh, or Lament for Ur in the original Sumerian? Jeez,
you had it rough. You'll be telling me next they didn't do
Greek or Latin. We were so sick of Sumerian by the 3rd year
that we were really glad to move on to heiroglyphics. |
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What, the American public?? |
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Yes ... "Populace formerly known as Joe Six-Pack", all reduced to little glyps. There's an app for it. |
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// We were so sick of Sumerian by the 3rd year that we were really glad to move on to heiroglyphics. // |
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Not surprising, all those Mesopotamian languages are cuneiformly dull and uninspired. |
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Wheatsheaf, wiggly line, sort-of boat-thing, beetle, beetle, giant eye, fish, beetle, thing like a hacksaw stood on end, big foot, palm frond ? Duck, fish, wiggly line, wiggly line, snake, lamp, Apollo 11 L.E.M. with mickey-mouse ears, beetle or possibly a 2CV with a parcel carrier ... papyrus reed, wheatsheaf, wheatsheaf, giant eye, symbol strangely like a crashed helicopter, beetle ! Smiley-face symbol, but in profile. |
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//Wheatsheaf, wiggly line, sort-of boat-thing, beetle, beetle,
giant eye, fish, beetle, thing like a hacksaw stood on end, big
foot, palm frond ? Duck, fish, wiggly line, wiggly line, snake,
lamp, beetle ... papyrus reed, wheatsheaf, wheatsheaf, giant
eye, duck, beetle ! Smiley-face symbol, but in profile.//
That's what she said. |
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That's what we thought ... we suppose that if it has to be explained, it's not actually funny. |
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The one about the High Priest, the jar of oil and the dancing girl was pretty good though. |
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It's even funnier when you realize that "wavey leaf" is actually
a pun. You only get it if you know Sumerian Rhyming Slang,
though. |
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//Oh, just the American public, then? Still, I guess that would make sense. The aliens probably came looking for sasquatch.// |
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America was a young country. They didn't have entrenched power-bases controlling information, it was a free-for-all. I think it tried to actually inform people there for a while before their politicians started getting shot and selling out. Hell, they were even allowed to have actual genius there for a bit. |
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But not anymore. People might get upset. |
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Sasquatches are alright in my book. They had every opportunity to harm me and didn't take it. I owe them one... unlike most people I've met. |
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Yes, gosh, you had a lucky escape there, [2fries]. |
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Naw, I think they're probably gentle, but they sure don't like it when you camp out in their ranges.
Ranges are those thousands and thousands of miles of old-growth trees on the sides of mountains.
Trees make up the large green sections on satellite images of North America. |
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It's almost like Sasquatch need those two things to not be imaginary for some folks.
Hey! If you guys replanted your forests I bet maybe some would come for a visit. |
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//Trees make up the large green sections on satellite images of North America.// except that light green one : that's Lake Erie, again. Oh, and Salton Sea, etc. |
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//If you guys replanted your forests I bet maybe some would
come for a visit.// I suspect it would be cheaper just to drink
a lot. |
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Why not both?!..
<gets carried around on shoulders of cheering crowd like that little girl in the Gorditas commercial>
Yeti digress. |
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The problem with the forests-and-drinking idea is that - in the summer - it might attract wandering Canucks (in the winter they're all too busy either playing or watching ice hockey). |
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So then you need a way of sorting them. Simplest thing is to wave an ice hockey stick in front of them - if they get excited, and try to hit one another on the head, there's your Canadians, right there. |
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You seem to be under the impression that hockey, forests and beer are mutually exclusive. |
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No, they're not, that's the problem. |
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You call it "a problem", I call it "February". |
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I reckon the collimator is useful. Without the
collimator, you can focus the sunlight to as small a
spot as possible, and make that spot the opening
of the liquid light guide. With the collimator, you
could focus it to an area maybe 10 times as large,
make that larger spot the opening to a larger
liquid light guide, after passing through the
collimator, then at the other end of the liquid light
guide, focus it to reduce the spot size 10 times, to
the same size as the version without the
collimator. The collimator wouldn’t give perfectly
parallel light, but it would be closer to parallel
than without it. |
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Advantages: less concentrated light until the final
focus, so it’s less damaging to anything that
absorbs it. Light is closer to parallel so it can be
reflected with total internal reflection. Light being
closer to parallel is taking a more direct path, so
less light loss due to reflections and absorption
along the liquid light guide. Disadvantage: the
light guide is bigger. |
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Ooh, I like that hand-held laser link! |
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If anyone has a spare one kicking around to lend I promise not to break into armored vehicles or anything with it. |
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I got bored a while ago, and worked out you could do
the Archimedes death ray thingy with as few as 1,800
soldiers with very shiny shields. Of course the pay was
lower in those day. |
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There's a hop-light joke in there somewhere. |
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