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COLLEGE PARK, Md.—Harry Potter may not have talked much about plasmonics in J. K. Rowling's fantasy series, but University of Maryland researchers are using this emerging technology to develop an invisibility cloak that exists beyond the world of bespectacled teenage wizards.
Originally posted by v4vendetta
WOW! I dont understand what i just saw, im a bit confused...
That video looks old aswell, imagine what the top guys are up to now...
Originally posted by bigfatfurrytexan
Many of you may have seen this article recently (there may have even been a thread started on it...but i don't recall and have watched closely)
Towards Cloaking Visible Light: Three-dimensional Metamaterials For The Optical Wavelength Range
Last year researchers from Duke University stunned the world when they announced a cloaking device for the microwave range. This device made use of metamaterials that had a negative refractive index for electromagnetic radiation. The metamaterials were carefully designed split-ring resonators with a structure size much smaller than the wavelength. Only 10 stacked layers of metamaterials were necessary to achieve the desired invisibility effect.
Possible applications in the future include perfect lenses that beat the diffraction limit, and optical cloaking devices which provide some invisibility for macroscopic objects
Very interesting indeed.
This isn't all that is being done using nanoscale science. I will be posting more data that shows some of the cloaking technology developed to date.
Consider, for example, the "Paint the Night" program run in the late 90's, headed by the great, late Mike Muuss (he also wrote "Ping", which is on virtually every computer in the world).
Now, if you consider the ability to create 'clouds' of vapor (each with a defined surface tension), you can see how the PTN technology could possibly evolve. Further that with airborne nano's (which can 'congeal' due to EM properties). Voila!!!
But this thread is about cloaking and invisibility. So on with the show!
[edit on 9-2-2008 by bigfatfurrytexan]
The Purdue University engineers, following mathematical guidelines devised in 2006 by physicists in the United Kingdom, have created a theoretical design that uses an array of tiny needles radiating outward from a central spoke. The design, which resembles a round hairbrush, would bend light around the object being cloaked. Background objects would be visible but not the object surrounded by the cylindrical array of nano-needles, said Vladimir Shalaev, Purdue's Robert and Anne Burnett Professor of Electrical and Computer Engineering.
The design does, however, have a major limitation: It works only for any single wavelength, and not for the entire frequency range of the visible spectrum, Shalaev said.
Calculations indicate the device would make an object invisible in a wavelength of 632.8 nanometers, which corresponds to the color red. The same design, however, could be used to create a cloak for any other single wavelength in the visible spectrum, Shalaev said.
"How to create a design that works for all colors of visible light at the same time will be a big technical challenge, but we believe it's possible," he said. "It is clearly doable. In principle, this cloak could be arbitrarily large, as large as a person or an aircraft."
Scientists have already created an 'invisibility cloak' made out of 'metamaterial' which can bend electromagnetic radiation such as visible light, radar or microwaves -- around a spherical space, making an object within this region appear invisible.
Until now, scientists could only make objects appear invisible from far away. Liverpool mathematician Dr Sébastien Guenneau, together with Dr Frédéric Zolla and Professors André Nicolet from the University of Marseille, have proven - using a specially designed computer model called GETDP - that objects can also be made to appear invisible from close range when light travels in waves rather than beams
Abstract: The diffractive nature of light has limited optics and photonics to operate at scales much larger than the wavelength of light. The major challenge in scaling-down integrated photonics is how to mold the light flow below diffraction-limit in all three dimensions. A high index solid immersion lens can improve the spatial resolution by increasing the medium refractive index, but only to few times higher than in air. Photonic crystals can guide light in three dimensions, however, the guided beam width is around a wavelength. Surface plasmons has a potential to reach the sub-wavelength scales; nevertheless, it is confined in the two-dimensional interface between metals and dielectrics. Here, we present a new approach for molding the light flow at the deep sub-wavelength scale, using metamaterials with uniquely designed dispersion. We develop a design methodology for realizing sub-wavelength ray optics, and demonstrate lambda/10 width light beams flow through three-dimensional space.
It sounds like a science fiction joke, but it isn't. What do you get when you turn an invisibility cloak on its side? A mini flying carpet.
So say physicists who believe the same exotic materials used to make cloaking devices could also be used to levitate tiny objects. In a further breakthrough, two other research groups have come a step closer to cracking the mysteries of levitation.
Scientists have levitated objects before, most famously using powerful magnetic fields to levitate a frog. But that technique, using the repulsive force of a giant magnet, requires large amounts of energy. In contrast, the latest theories exploit the natural smaller amounts of energy produced by the quantum fluctuations of empty space.
The device was formed from so-called "metamaterials", exotic materials made from complex arrays of metal units and wires. The metal units are smaller than the wavelength of light and so the materials can be engineered to precisely control how electromagnetic light waves travel around them. "They can transform space, tricking electromagnetic waves into moving along directions they otherwise wouldn't," says Leonhardt.
Capasso and his colleagues have also been working on an alternative scheme to harness a repulsive Casimir effect. Their calculations show that a repulsive Casimir force could be set up between a 42.7 micrometre-wide gold-coated polystyrene sphere and a silicon dioxide plate, if the two are immersed in ethanol. "Although the Casimir force between any two substances – the ethanol and gold, the gold and the silicon dioxide, or the silicon dioxide and the ethanol – is positive, the relative strengths of attraction are different, and when you combine the materials, you should see the gold sphere levitate," he says.
The design of the cloaking materials, published in the New Journal of Physics, shows that making an acoustic shield "can be done in a straightforward and simple way," says Steven Cummer, an electrical engineer at Duke University who was involved in the construction of the first light cloak in 2006.
Building on the theoretical work of John Pendry at Imperial College in London, a group at Duke University led by David R. Smith and including Cummer created a shield that makes objects invisible to a particular frequency of microwave light. They used metamaterials, artificially structured composites designed to have properties unmatched by natural materials. For about 10 years, engineers have been designing metamaterials to manipulate light in the hope of creating new display technologies, microscope lenses, and computer chips dense with transistors. The new acoustic-cloak recipe builds on Cummer's recent theoretical work on acoustic materials, and it shows that metamaterials can be used to manipulate sound waves as well as light waves. Cummer, who was not involved in Sánchez-Dehesa's work, says that it should now be possible to fabricate an acoustic cloak.