Chinese Scientists Create an Invisibility Cloak

by Susan Mwai, age 16

The Chinese are making an invisible fabric that people can hide behind -an invisibility cloak. And until now, it seemed like something impossible.

The cloaks are made out of metamaterials, which are created by putting together patterns of structures that interact with the light they are designed to cloak. Such specific technology makes the production process very expensive and time-consuming. Even so, the completed cloaks are never perfect; so physicists tried to see if there was a simpler way to make them.

With a new material comes a new technique for how these cloaks are made. The metamaterial approach works by trying to guide electromagnetic fields around an object in a way that hides it. The new approach is to create a computer model of the cloak in the form of a conventional material with fixed light-bending properties. The material distorts light as it passes by, through. To reduce this distortion, the scientists use the computer to change the shape and topology of the material.

By repeating this process many times, they find a topology that minimizes the distortion of light so it remains unchanged as it passes by, resulting in a working invisibility cloak.

Researcher Lu Lan and some colleagues at Zhejiang University in Hangzhou, China created the first invisibility cloak using topology optimization.

It was carved out of Teflon (durable plastic made of non-stick coating) and it took them 15 minutes.

The cloak can hide a disk of metal the size of a poker chip from microwaves. There is a great significance with this because it is the first step in a process that could bring invisibility cloaks into mass production.

Lu Lan and colleagues want to expand the technique and create cloaks that work over a range of frequencies and at a range of angles.

If they can make them cheaply and easily, invisibility cloaks may no longer be the stuff of fantasy.

[Source: The Technology Review]