The invisibility cloak has long been an idea present mostly in comic books and sci-fi novels — remember the Cloak of Invisibility from J.K. Rowling's "Harry Potter" books or the scramble suit from Philip K. Dick's "A Scanner Darkly"?
Well, every spy's dream is now one step closer to reality thanks to the work of researchers from the University of Texas, Austin, which have developed an ultra-thin material called a "metascreen".
Titled "Demonstration of an ultralow profile cloak for scattering suppression of a finite-length rod in free space," their research, published in the New Journal of Physics, describes a cloak consisting of 66 µm-thick copper tape and 100 µm-thick flexible polycarbonate film which scatters and cancels out incoming waves.
The researchers used the cloak to shield an 18 cm tall cylindrical rod from microwaves.
The cloak works optimally at 3.7GHz, researchers say, but it could be applied to visible frequencies.
"In principle this technique may be extended to visible frequencies; in fact metasurfaces are easier to realize than metamaterials in optics. However, the object size that can be efficiently cloaked with this method scales with the wavelength, so when applied to optical frequencies we may be able to efficiently stop the scattering of only micrometer-sized objects," the research paper claims.
So there you have it: a cloak that shields objects from vision is a very real possibility, but in this case it would only work well on very small objects.
It does not mean this technology is without use, though. The researchers see a variety of cloaking applications for small objects, such as optical nanotags and nanoswitches, as well as improving the absorption efficiency of nanoparticles.
Image credit: New Journal of Physics