 |
| A photo of the "metamaterial" cloak, released to Reuters on October 19, 2006, which deflects microwave beams so they flow around a "hidden" object inside with little distortion, making it appear almost as if nothing were there at all. U.S. and British scientists said on Thursday they had found a way to hide an object from microwave radiation in a first step toward making a what they hope will be an invisibility cloak. [Reuters] |
Scientists are boldly going where only fiction has gone before - to develop aCloak of Invisibility. It isn't quite ready to hide a Romulan space ship from Capt. James T. Kirk or to disguise Harry Potter, but it is a significant start and could show the way to more sophisticated designs.
In this first successful experiment, researchers from the United States and England were able to cloak acopper cylinder.
It's like amirage, where heat causes the bending of light rays and cloaks the road ahead behind an image of the sky.
"We have built an artificial mirage that can hide something from would-be observers in any direction," said cloak designer David Schurig, a research associate in Duke University's electrical and computer engineering department.
For their first attempt, the researchers designed a cloak that preventsmicrowavesfrom detecting objects. Like light and radar waves, microwaves usually bounce off objects, making them visible to instruments and creating a shadow that can be detected.
Cloaking used special materials to deflect radar or light or other waves around an object, like water flowing around a smooth rock in a stream. It differs from stealth technology, which does not make an aircraft invisible but reduces the cross-section available to radar, making it hard to track.
The new work points the way for an improved version that could hide people and objects from visible light.
Conceptually, the chance of adapting the concept to visible light is good, Schurig said in a telephone interview. But, he added, "From an engineering point of view it is very challenging."
The cloaking of a cylinder from microwaves comes just five months after Schurig and colleagues published their theory that it should be possible. Their work is reported in a paper in Friday's issue of the journal Science.
"We did this work very quickly ... and that led to a cloak that is notoptimal," said co-author David R. Smith, also of Duke. "We know how to make a much better one."
The cloak is made of metamaterials, which are mixtures of metal and circuit board materials such as ceramic, Teflon or fiber composite.
In an ideal situation, the cloak and the item it is hiding would be invisible. An observer would see whatever is beyond them, with no evidence the cloaked item exists.
(Agencies)
|
开心
人人
豆瓣
白社会
新浪微博
MySpace
Digg
Yahoo! Buzz
Linkedin
Mixx
