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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.
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.
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.
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.
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
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.
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