UC Berkeley’s Invisibility Cloak

September 24, 2015 by Jennifer A. Diffley

Nanoantennas, light, and tricking the mind: the technology behind UC Berkeley's invisibility cloak

For those of us not adept at wizardry, invisibility cloaks seemed a far-fetched notion relegated to the likes of fairy tales and children's books. But this month UC Berkeley announced it had made progress on an invisibility cloak...kind of. Previous attempts at concealment have come in the form of metamaterials that essentially redirect light around an object, but the applications were targeted more for industrial and science uses, such as making more efficient satellite communication. 

But the UC Berkeley research is a step in a different direction. The cloak "conceals a three-dimensional arbitrarily shaped object by complete restoration of the phase of the reflected light at 730-nanometer wavelength," but at the moment the size of the cloak is limited to about 1,300 square microns (roughly .001300000 square millimeters).

A rendering of light being redirected by nanoantennas.

The cloak works by relying on the way the human eye detects objects: essentially, we "see" by analyzing light. Our eyes evaluate objects and colors based on the way light bounces off them. The engineers at Berkeley comprised their cloak of nanoantennas that manipulate light distortion to trick the mind into believing the object being concealed is a flat surface rather than a protruding object (more on nanoantennas and their properties here). It's a small step in the right direction, and scientists hope that eventually the technology can be applied to larger objects and eventually everything from concealing people to hiding aircraft. 

Interestingly enough, the technology can also work in reverse, making flat objects seem multi-dimensional. It could go a step beyond holograms, making objects that genuinely appear solid instead of a Princess Leia-like mirage.

There's still quite a bit of work to do and scientists estimate they're still at least a decade off from making anything resembling Harry Potter's famous cloak, but at least now that option is a definite possibility.