Tuesday, November 13, 2012

Scientists produce 'perfect' invisibility cloak

Scientists have been saying they could produce an invisibility cloak for some time, and they now say they have produced a "perfect demonstration." While perhaps as not as perfect as the cloak in the "Harry Potter" films, the One Ring in "Lord of the Rings," or the cloaking device in Star Trek, researchers at Duke University made the announcement on Monday.

The first functional "invisibility cloak" device was reported by Duke University electrical engineers in 2006. While it worked, there were issues, including minor reflections around the edges, which were were similar to the reflections seen when looking through a clear pane of glass.

Graduate student Nathan Landy, speaking for the research team, said:
In order to create the first cloaks, many approximations had to be made in order to fabricate the intricate meta-materials used in the device. One issue, which we were fully aware of, was loss of the waves due to reflections at the boundaries of the device.

Since the goal was to demonstrate the basic principles of cloaking, we didn't worry about these reflections.
How by altering the fabrication methodology, the research team managed to get around that issue, however.

The original cloak consisted of parallel and intersecting strips of fiberglass etched with copper, but while the new version uses a similar row-by-row design, it includes added copper strips to create a more complex and better-performing meta-material.

Landy said,
Each quadrant of the cloak tended to have voids, or blind spots, at their intersections and corners with each other. After many calculations, we thought we could correct this situation by shifting each strip so that it met its mirror image at each interface.

We built the cloak, and it worked. It split light into two waves which traveled around an object in the center and re-emerged as the single wave with minimal loss due to reflections.
It's perfect, but imperfect. The illusion only works from one direction, meaning two-dimensionally. Naturally, you aren't going to cloak a starship with this material, either (as shown in the embedded video).

No comments: