Inviso-tech Takes One Theoretical Step Forward

They can, theoretically, cause light to bend completely around an object. Drawbacks: Only one wavelength of light (red) can be made invisible.

Still. They're ahead of all of my work in this field, which is focused chiefly on trying to convince potential enemies to stick turkey forks in their eyes.

Researchers 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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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."

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Other researchers have developed concepts for cloaking objects smaller than the wavelengths of visible light and for objects detected in the microwave range of the spectrum, which are much larger than the wavelengths of visible light. But the new design is the first for cloaking an arbitrary object in the range of light visible to humans.

"What we propose is the cloaking of objects of any shape and size," Shalaev said.

Nanotech plays a role. It's all nanotech these days. Maybe you boys need a refresher course.

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Natural materials typically have refractive indices greater than 1. The new design reduces a refractive index to values gradually varying from zero at the inner surface of the cloak, to 1 at the outer surface of the cloak, which is required to guide light around the cloaked object.

Creating the tiny needles would require the same sort of equipment already used to fabricate nanotech devices. The needles in the theoretical design are about as wide as 10 nanometers, or billionths of a meter, and as long as hundreds of nanometers. They would be arranged in layers emanating from a central spoke in a cylindrical shape. A single nanometer is roughly the size of 20 hydrogen atoms strung together.

Thanks to CraigC.

posted by Ace at 01:41 PM

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