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Tapering Waveguide Captures a Rainbow
SubComdTaco passes along news of researchers in the US who have trapped a rainbow in a tapering waveguide. The research is described (PDF) on the arXiv. "In 2007, Ortwin Hess of the University of Surrey in Guildford, UK, and colleagues proposed a technique to trap light inside a tapering waveguide [made of metamaterials]... The idea is that as the waveguide tapers, the components of the light are made to stop in turn at ever narrower points. That's because any given component of the light cannot pass through an opening that's smaller than its wavelength. This leads to a 'trapped rainbow.' ... Now Vera Smolyaninova of Towson University in Baltimore, Maryland, and colleagues have used a convex lens to create the tapered waveguide and trap a rainbow of light. They coated one side of a 4.5-mm-diameter lens with a gold film..., and laid the lens — gold-side down — on a flat glass slide which was also coated with film of gold. Viewed side-on, the space between the curved lens and the flat slide was a layer of air that narrowed to zero thickness where the lens touched the slide — essentially a tapered waveguide. When they shone a multi-wavelength laser beam at the... gilded waveguide, a trapped rainbow formed inside. This could be seen as a series of colored rings when the lens was viewed from above with a microscope: the visible light leaked through the thin gold film."
So the bloody leprechaun lied to us !
You need to have two very thin pots of gold first, so you can find the end of the rainbow.
But the ends still technically had gold beneath them.
A bullet may have your name on it but splash damage is addressed "To whom it may concern."
did they try tasting it?
Snowden and Manning are heroes.
Dr. Hess was later quoted as saying, "While we're obviously pleased with our success so far, we won't be satisfied until we've trapped not only the rainbow, but the leprechaun and pot of gold as well. Until then, we remain disturbingly dependent on grant money for our research."
>>You need to have two very thin pots of gold first, so you can find the end of the rainbow.
I wonder if you kidnap the scientists they'll grant you three wishes?
Tag: Leprechaun
"If humans could put Rainbows in a Zoo, they would."
--Bill Watterson, via Hobbes in Calvin and Hobbes.
Demented But Determined.
Obviously if you can see it the rainbow isn't completely contained. You can't capture a rainbow in the manner that you're thinking of because it would require a perfect vacuum (which we can mostly achieve these days), and a perfectly reflective surface (which we cannot). Every time the light bounces off of whatever you have contained it in, it will lose a bit of energy. Since it's traveling at the speed of light, you'll have enormous numbers of bounces per second and they'll quickly sap all of the energy away from the beam.
I read the internet for the articles.
Okay, aside from the obvious "nifty" factor, can someone explain in dummy-terms what other cool stuff this might lead to? I realize that research isn't necessarily about making immediately useful things, but surely someone knows of some fantastic avenues this might lead towards?
Not trying to downplay any significance here, just looking for some insight from someone more familiar with what's going on. :)
Their may be a grammatical error, misspeling, or evn a typo in this post.
Soap bubbles are better because I can make them myself, they float around in the air and they look like little gas planets with swirling atmospheres.
Seastead this.
Just don't stand too close to the cell.
Table-ized A.I.
Sounds like an old high school science experiment. Take two microscope slides (flat pieces of glass) lay one on top of another with a thin shim separating them at one end, illuminate this with a monochromatic light and see the fringes. With white light, the peaks for each wavelength would occur at different locations, resulting in a 'rainbow'. Same thing works with soap films, using internal reflection, as the film flows downwards due to gravity and becomes thicker at the bottom (wedge-shaped).
This is also a neat trick for measuring the thickness (or diameter) of a small object. Using it as the shim, count the fringes per centimeter, do some math and you know how thick it is.
Have gnu, will travel.
Selective absorption is a well known effect that takes place whenever a wave propagates in a medium where two boundary conditions have to be fulfilled at once. We observe it regularly in our lab while sending acoustic/elastic waves into a pack of slabs of material. The same thing happens with electromagnetic waves, just like Isaac Newton observed a few centuries ago. Sending the light in a direction parallel to the lenght rather than perpendicular does not discover anything new. Next post, please...
Just because we create something does not mean that we can claim ownership of it, I wonder if that's why no one has ever seen god?
I think the RIAA might disagree with you on the first point.
And no one has seen God because he's been involved in a long legal battle with Michael Jackson over buying back the rights to "The Universe" back catalogue.
Sounds like an old high school science experiment. Take two microscope slides (flat pieces of glass) lay one on top of another with a thin shim separating them at one end, illuminate this with a monochromatic light and see the fringes. With white light, the peaks for each wavelength would occur at different locations, resulting in a 'rainbow'.
What you're referring to is known as "Newton's Rings":
http://en.wikipedia.org/wiki/Newton's_rings
Your musings sound not so much like Asimov's fiction, but futurist Ray Kurzweil's predictions in books like The Singularity is Near . One of Kurzweil's observations is that as soon as we can create a machine equivalent to a human brain, we can create a machine more powerful than a human brain.
Interesting theory, but where does this energy go ? Is it converted to sound, heat, mass, or some other form ?
Heat.
And if we could completely "sap all the energy" away from the beam, wouldn't this imply we could create 100% effecient solar cells ?
As long as you're happy with heat as output, 100% efficient solar cells are quite trivial.
Finally! A year of moderation! Ready for 2019?
It was a very simple experiment to perform. It doesn't make any measurement of the group velocity or demonstration of trapped light (which would typically involve releasing it controllably and detecting it). The original proposal involved meta-materials to achieve a region with a negative index of refraction to use as the waveguide. They could then (hopefully) manipulate the meta-material to controllably store and retrieve light.
It seems this experiment used a simple meta-material the consisted of the glass surfaces, the 30-nm gold coating and the air gap in a Newton's rings setup. They may even have had the gold coated lens lying around and did the experiment over lunch (which just involved taking a picture). I don't think it's all that interesting until they get storage and retrieval.
So if this is the future...where's my jet pack?
As far as the reflection losses go, it's not converted to anything, it's transmitted. That's what the GP meant by "if you can see it the rainbow isn't completely contained". There's no such thing as a perfect reflector, some of the light is always transmitted through. And since we can't attain perfect vacuum, there will also be internal collisions with gaseous molecules, which can either transmit the absorbed energy via heat in colliding with other molecules, or re-transmit it as light, though possibly in a series of longer wavelengths.
As for the solar cells thing... no. That's a completely different situation. The trapped rainbow is a nearly closed system, with no continuous energy input, and the problem is that we can't make it completely closed (and if we could, it's internal entropy would then increase over time so it still couldn't be perfectly stable). Technically, I suppose all the energy can't be sapped since it's exponential decay, but the system energy asymptotically approaches 0 (and once a small enough amount remains, the fact the energy is discrete becomes important). It's about inefficient energy conversion. Far form implying that we could create 100% efficient solar cells, this is why we can't create 100% efficient solar cells.
it is all lost to heat.
wouldn't this imply we could create 100% effecient solar cells ?
No, just very very black objects that get hot in the sun. If you could make them NOT get hot, get heavier, or vibrate then YES, you would be rich.
THL phish sticks
It's in, well, Towson, which is in Baltimore County, MD.
I'm a consultant - I convert gibberish into cash-flow.
No, my comment has been "cool-for-saled" ... it's the Rickrolling of 2009.
coolforsale.com Chinese spam scam sweatshop illegal copies half your money back do not buy
As long as you're happy with heat as output
So how about we create a tiny stirling engine and put it at the end of two gold plated cone shapes, one inside the other with a tiny tapering distance between them, and for good measure, enclosed in a vacuum ?
Wouldn't this allow the incoming light source to be trapped on 3 dimensions and focused down to a concentrated point ? Sure we couldn't see the rainbow any more, but the "light leakage" concerns would seem to be covered, and by the comments above, the only place the light could "go to" would be 100% into the heat collector end of the sitrling engine.
Multiply this up by thousands in an array, and you might have the next "solar collector" design.
While similar in effect to an interference patter type experiment, the actual physics behind the experiment in the article is subtly different. A 'Newtons Rings' type pattern emerges when the distance between the two (partially) reflective surfaces are a certain distance apart, coinciding with an integer value of wavelengths of the light involved. This can can, in theory, be any distance, as long as exact number of wavelengths fit inside. For example, standard interferometers can have distances as large as a centimetre, which is huge compared to the wavelength of visible light.
The effect described is based on the distance between two very reflective surfaces being smaller than the wavelength of light involved, thus preventing the light from travelling further down the waveguide. The taper on the waveguide means that as you go to shorter wavelengths of light, it can travel further, thus generating a 'trapped rainbow' of visible light inside the waveguide.
A key difference to note is that the fringe pattern generated by an interferometer type setup repeats itself as you increase/decrease the distance between the two reflective surfaces, so generating a series of lines or concentric circles. The setup with the 'trapped rainbow' will create a single rainbow pattern.
Ummm, if we could produce a computer (and program it) to be equivalent to the human brain, wouldn't *IT* be making the next one? Come on, it wouldn't need sleep. It wouldn't take weekends off. It wouldn't take smoke breaks. It wouldn't go on shooting rampages when it was overstressed and underpaid (I hope). It wouldn't only work 8 to 14 hour days. It wouldn't have to stop working to take a leak. It wouldn't be having dirty dreams about that hot 18 year old intern named Natasha (MMmm, Natasha). It wouldn't have it's wife nagging that he spends long hours at work to spend time with the hot 18 year old intern. He wouldn't have to come up with convincing lies to explain the difference between his 8 hour work day and the 14 hours a day that he's "at work". You get the idea. :)
They never did mention that Skynet was powered by a captured rainbow. Heck, I don't think I've ever heard of any scifi like that. Captured singularities; gravity wells; portals to evil domains, sure, but never a captured rainbow.
Serious? Seriousness is well above my pay grade.
That was my thought on it. They aren't "capturing" it. They're looking at refracted light. It's a very fancy prism. They spent a lot of money on water drops. Otherwise, they should be able to quantify the photon dust on the bottom of their apparatus. :) ... and I was just making a joke about the photon dust, but I googled it, and it's theorized to exist. Well, kinda. :)
I guess there's gotta be something at the bottom of a black hole from all that light that can't escape, right? :)
Serious? Seriousness is well above my pay grade.
oh your one of those people that think IQ is everything and strength or stamina are not neccessary
Playing devil's advocate here (the poster you're responding to is a lame troll posting the same crap over and over again, and you're also pretty wrong to say that genetically Africans tend to be great athletes and Westerners are better scientists) - stamina and strength can both be acquired through training, intelligence only in a very limited fashion. So yeah, intelligence is more precious than physical strength.
A good education is a bit like a STD - it makes you unsuitable for a lot of jobs and gives you a desire to spread it.
One of Kurzweil's observations is that as soon as we can create a machine equivalent to a human brain, we can create a machine more powerful than a human brain.
Which would also mean that we wouldn't be that far away from creating a machine capable of enhancing the human brain.
A good education is a bit like a STD - it makes you unsuitable for a lot of jobs and gives you a desire to spread it.
You're over engineering this. We can already use pretty good mirrors to focus light onto a tower and heat salt then proceed to make steam and use general turbines. Just look at PS10 and PS20
And then, the rainbows turned on us, the seven frequencies combining their harmonics into a single meta-Frequency
A frequency . . . of DEATH!!!!!
RUN - SAVE YOURSELVES!!!!
An Invisible Entity of Vast Power whose existence must be taken on faith alone: Liberal Media