How Invisibility Cloaks Work :
Admit it. You’d love to own an invisibility cloak. Utter an embarrassing faux pas at a party? Just throw on your magical garment and vanish from the snooty gaze of your fellow partygoers. Want to hear what your boss is really saying about you? Stroll right into his or her office and get the goods.
Such fantastic fashion accessories have become ridiculously standard in the world of science fiction and fantasy. Everyone, from boy wizards to intergalactic safari hunters, has at least one invisible blouse in their wardrobe, but what about us poor saps in the real world?
Well, Muggles, science has some good news for you: Invisibility cloaks are a reality. The technology is far from perfect, but if you’ll step into our high-tech boutique of vanishing apparel, we’ll guide you through your invisibility cloak options.
First up, we’ll look at some wonderful carbon nanotube fashions — fresh from the UTD NanoTech Institute fall 2011 collection. This new technology is inspired by the same natural phenomena responsible for desert mirages. Heated via electrical stimulation, the sharp temperature gradient between the cloak and the surrounding area causes a steep temperature gradient that bends light away from the wearer. The catch: Wearers must love water and be able to fit inside a petri dish.
Or perhaps you’d prefer something made from metamaterials. These tiny structures are smaller than the wavelength of light. If properly constructed, they guide rays of light around an object — much like a rock diverting water in a stream. For now, however, the technology only works in two dimensions and only comes in the ultrapetite size of 10 micrometers across.
If you’re more into retro fashion, there’s also the optical camouflage technology developed by scientists at the University of Tokyo. This approach works on the same principles of the blue screen used by TV weather forecasters and Hollywood filmmakers. If you want people to see through you, then why not just film what’s behind you and project it onto your body? If you travel with an entourage of videographers, this may be the cloak for you.
Ready to try some of these fashions on for size?
Negative index metamaterial array configuration, which was constructed of copper split-ring resonators and wires mounted on interlocking sheets of fiberglass circuit board. The total array consists of 3 by 20×20 unit cells with overall dimensions of 10×100×100 mm.
Metamaterials (from the Greek word “meta-“, μετά- meaning “to go beyond”) are smart materials engineered to have properties that have not yet been found in nature. They are made from assemblies of multiple elements fashioned from composite materials such as metals or plastics. The materials are usually arranged in repeating patterns, at scales that are smaller than the wavelengths of the phenomena they influence. Metamaterials derive their properties not from the properties of the base materials, but from their newly designed structures. Their precise shape, geometry, size, orientation and arrangement gives them their smart properties capable to manipulateelectromagnetic waves: by blocking, absorbing, enhancing, bending waves, to achieve benefits that go beyond what is possible with conventional materials.
Appropriately designed metamaterials can affect waves of electromagnetic radiation or sound in a manner not observed in bulk materials.Those that exhibit a negative index of refraction for particular wavelengths have attracted significant research.These materials are known as negative index metamaterials.
Potential applications of metamaterials are diverse and include optical filters, medical devices, remote aerospace applications, sensordetection and infrastructure monitoring, smart solar power management, crowd control, radomes, high-frequency battlefield communication and lenses for high-gain antennas, improving ultrasonic sensors, and even shielding structures from earthquakes.[9][10][11][12] Metamaterials offer the potential to create superlenses. Such a lens could allow imaging below the diffraction limitthat is the minimum resolution that can be achieved by a given wavelength. A form of ‘invisibility’ was demonstrated using gradient-index materials. Acoustic and seismic metamaterials are also research areas.
Metamaterial research is interdisciplinary and involves such fields as electrical engineering, electromagnetics, classical optics, solid state physics, microwave and antennae engineering, optoelectronics, material sciences, nanoscience and semiconductor engineering.
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