INVISIBILITY cloaks that work at optical wavelengths are a step closer to reality thanks to a different take on the problem.In previous attempts fiendishly small structures had to be precisely positioned in the cloaking material. However, super-thin layers of much simpler stuff should do the trick.
Invisibility cloaks burst into the public consciousness last year, when a transatlantic team unveiled both the theory and a working device. Engineering constraints only allowed them to construct a cloak that could hide a very small object at microwave wavelengths, as confirmed by a microwave detector, and they warned that to achieve the same feat at optical wavelengths would require an extremely difficult leap in miniaturisation.
Now, Yijun Feng, a physicist from Nanjing University, China, and colleagues are trying a new approach that significantly reduces the complexity of the cloaking fabric.
Posts Tagged ‘cloaking device’
Cloaking Device Activate
Sunday, September 16th, 2007Cloaking Device Activated
Monday, April 2nd, 2007Researchers using nanotechnology have taken a step toward creating an “optical cloaking” device that could render objects invisible by guiding light around anything placed inside this “cloak.”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.
“But this is a first design step toward creating an optical cloaking device that might work for all wavelengths of visible light,” he said.
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Leonhardt says in his commentary that creating a cloak for rendering total invisibility in the entire visible spectrum would require “further advances in optical metamaterials, new combinations of nanotechnology with highly abstract ideas …”
