Scientists are getting much closer to achieving a perfect “cloak of invisibility,” this time using a diamond-shaped device to help clean up some of the loose ends from previous attempts.
Building on research done in 2006, electrical engineers at Duke University in Durham, N.C., have improved how the edges of their “cloak” work, allowing light to pass around an object without reflections so that the human eye can’t see it. Light waves are bent around the object, making it appear not to be there.
The trick was to use a diamond-shaped cloak developed by graduate student Nathan Landy with properties carefully matched at the diamond’s corners, to move light waves perfectly around a cylinder.
The researchers say they have used “a similar row-by-row design” to previous attempts, but added copper strips to create a more complicated — and better performing — material.
The results of their work were published Nov. 11 in the online journal Nature Materials.
David R. Smith — who worked on the previous research — and Landy say the new findings could be important in transforming how light or other waves can be controlled or transmitted.
In the same way that wires gave way to fiber optics, the new meta-material could change the way light and waves are transmitted.
In earlier attempts, the materials used allowed for some “wave loss,” which meant people could see cloaked objects around the edges. The effect was akin to being able to see reflections in a piece of clear glass, while still seeing through it .
“Since the goal was to demonstrate the basic principles of cloaking, we didn’t worry about these reflections,” Landy said in a Duke release.
Those reflections have now been reduced using a different strategy with added copper strips. The original cloak consisted of parallel and intersecting strips of fiberglass etched with copper.
“This to our knowledge is the first cloak that really addresses getting the transformation exactly right to get you that perfect invisibility,” Smith told BBC News.
“It’s like the card people in Alice in Wonderland. If they turn on their sides, you can’t see them, but they’re obviously visible if you look from the other direction.”
The research was partly funded by the U.S. Office of Naval Research and the Army Research Office.
External Links
A full-parameter unidirectional metamaterial cloak for microwaves
Cloaking demonstration — diamond
Cloaking demonstration — circle
