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Title: Scientists create first cloaking device
Source:
Xinhua
URL Source: http://news.xinhuanet.com/english/2006-10/20/content_5229172.htm
Published: Oct 19, 2006
Author: Unattributed
Post Date: 2006-10-21 11:14:02 by Tauzero
Keywords: None
Views: 66
Comments: 2
Scientists create first cloaking device www.chinaview.cn 2006-10-20 15:52:57 LOS ANGELES, Oct.19 (Xinhua) -- Scientists have created the first cloaking device to demonstrate the theory of hiding an object from electromagnetic radiation. The cloak deflects microwave beams so they flow around an inside object with little distortion, making it appear almost as if nothing were there at all, a group of researchers reported in the Oct.19 online advance edition of the journal Science. Cloaks that render objects essentially invisible to microwaves could have a variety of wireless communications or radar applications, according to the team led by scientists at the U.S. Duke University. The first device is far from perfect in that it is barely 8-cm wide and can only reduce back scatter and forward scatter, the researchers said. But the achievement represents "one of the most elaborate metamaterial structures yet designed and produced," they wrote in the Science paper. It also represents the most comprehensive approach to invisibility yet realized, with the potential to hide objects of any size or material property, they added. To make an object literally vanish before a person's eyes, a cloak would have to simultaneously interact with all of the wavelengths, or colors, that make up light. That technology would require much more intricate and tiny metamaterial structures, which scientists have yet to devise. Earlier scientific approaches to achieving "invisibility" often relied on limiting the reflection of electromagnetic waves. In other schemes, scientists attempted to create cloaks with electromagnetic properties that cancel those of the object meant to be hidden, thus a given cloak could only hide objects with very specific properties. In the latest study, the team produced the cloak based on electromagnetic specifications determined by a new design theory proposed by British scientists, who reported that theoretical work in Science earlier this year. The researchers manufactured the cloak using "metamaterials" precisely arranged in a series of concentric circles that confer specific electromagnetic properties. Metamaterials are artificial composites that can be made to interact with electromagnetic waves in ways that natural materials cannot reproduce. "By incorporating complex material properties, our cloak allows a concealed volume, plus the cloak, to appear to have properties similar to free space when viewed externally," said David Smith, a professor at Duke University who led the study. While the properties of natural materials are determined by their chemistry, the properties of metamaterials depend instead on their physical structure. In the new cloak, that structure consists of copper rings and wires patterned onto sheets of fiberglass composite that are traditionally used in computer circuit boards. The cloak design is unique among metamaterials in its circular geometry and internal structural variation, the researchers said. All other metamaterials have been based on a cubic, or grid like, design, and most of them have electromagnetic properties that are uniform throughout. To assess the cloak's performance, the researchers aimed a microwave beam at a cloak situated between two metal plates inside a test chamber, and used a specialized detecting apparatus to measure the electromagnetic fields that developed both inside and outside the cloak. By examining an animated representation of the data, they found that the wave fronts of the beam separate and flow around the center of the cloak. It was similar to river water flowing around a smooth rock, they said. Moreover, the observed physical behavior of the cloak proved to be in "remarkable agreement" with that expected based on a simulated cloak, the researchers said. Although the new cloak demonstrates the feasibility of the design, the findings nevertheless represent a first step on the road to actual invisibility, noted the researchers. Next, they plan to develop a real three-dimensional cloak and further perfecting the cloaking effect.
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#1. To: Tauzero (#0)
Yikes!
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