Physics

New invisibility cloak hides tiny three-dimensional objects of any shape

An ultra-thin invisibility cloak developed at UC Berkeley can wrap around objects of any shape and conceal them from sight
An ultra-thin invisibility cloak developed at UC Berkeley can wrap around objects of any shape and conceal them from sight
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Yuan Wang, Zi Jing Wong and Xiang Zhang have devised an ultra-thin invisibility "skin" cloak that can conform to the shape of an object and conceal it from detection with visible light
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Yuan Wang, Zi Jing Wong and Xiang Zhang have devised an ultra-thin invisibility "skin" cloak that can conform to the shape of an object and conceal it from detection with visible light
An ultra-thin invisibility cloak developed at UC Berkeley can wrap around objects of any shape and conceal them from sight
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An ultra-thin invisibility cloak developed at UC Berkeley can wrap around objects of any shape and conceal them from sight

Scientists at UC Berkeley have developed a foldable, incredibly thin invisibility cloak that can wrap around microscopic objects of any shape and make them undetectable in the visible spectrum. In its current form, the technology could be useful in optical computing or in shrouding secret microelectronic components from prying eyes, but according to the researchers involved, it could also be scaled up in size with relative ease.

Objects are visible to us because a small portion of the light that hits them is scattered in the direction of our retinas. Invisibility cloaks can make objects disappear from sight by exploiting the unusual optical properties of so-called metamaterials. These special man-made compounds can manipulate light in unique ways to guide it around the surface of the cloak, so that no light is reflected from it or the object it's shielding.

Cloaks have already been devised that work in the visible, infrared and ultraviolet portions of the electromagnetic spectrum. However, while successful in bending light around an object, these devices also disturb the phase of the electromagnetic wave; so, while the object remains hidden as no light is reflected off it, the cloak itself can still be spotted through specialized instruments. What's more, these devices also tend to be very bulky and hard to scale up in size.

A team led by UC Berkeley's Xiang Zhang has now leveraged significant advances in metamaterial engineering to design an improved cloak that is especially thin (only 80 nanometers thick), does not suffer from the phase detection problems of previous cloaks, works in the visible light spectrum, and could reportedly be scaled up to shield macroscopic objects.

Yuan Wang, Zi Jing Wong and Xiang Zhang have devised an ultra-thin invisibility "skin" cloak that can conform to the shape of an object and conceal it from detection with visible light
Yuan Wang, Zi Jing Wong and Xiang Zhang have devised an ultra-thin invisibility "skin" cloak that can conform to the shape of an object and conceal it from detection with visible light

The cloak works by using arrays of gold nanoantennas, with each one manipulating the phase of the light wave that is scattered off the cloak. When a cloaked object is illuminated by 730-nanometer wavelength (deep red) light, the antennas make the cloak act like a perfectly flat mirror, regardless of its current shape.

Zhang and team tested their invention by wrapping the cloak around a cell-sized object with a highly irregular shape. As expected, when red light struck the cloak, it reflected off its surface as if off a flat mirror, making the object beneath it invisible even by phase-sensitive detection. When the polarization of the nanoantennas was changed, the cloaking effect stopped entirely.

"This is the first time a 3D object of arbitrary shape has been cloaked from visible light," says Zhang. "Our ultra-thin cloak now looks like a coat. It is easy to design and implement, and is potentially scalable for hiding macroscopic objects."

While the ability to pull a Harry Potter with a large-scale version of this cloak may be years away, the current version could already find use in hiding sensitive layouts of electronic components or aiding the development of optical computers.

A paper detailing the study appears in the journal Science. You can see the cloak in action in the short video below.

Source: Berkeley Lab

Nanoantenna Invisibility Cloak Makes 3D Objects Disappear

6 comments
S Michael
Not making the object disappear. Its refracting the light. Geez This is not good science. I can make objects at the bottom of my pool disappear by making multiple waves (not very big waves)which refracts the light and distorts the view. Do better than this.
Nik
So once you've wrapped the object, and its invisible, how do you find it?
Stephen N Russell
Markets for IF perfected & replicated Security Defense: Navy, Air Force, NSA?? Recon use: use in field to recon target area for strike. Hostage rescue: hide hostages & move DoD has to fund this big time. Fodder for next 007, Marvel, Iron Man, etc movies alone.
windykites
I have something that does a similar job. It is a black cloth. I wrap up the object, and it becomes invisible. Simple! I don't suppose this has anything to do with the Philadelphia Project?
Douglas Bennett Rogers
A virtual flat mirror is constructed, which will only hide the target if the scene behind the illuminant is able to be splined into the background.
Don Duncan
We can't see the object, but what do we see? What's behind it? Beside it? Or does the mirror effect show us ourselves, as in a small cameo? The report is incomplete.
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