Image: Andreas Weiser/Flickr
Every now and then a story comes around that so-and-so scientist has developed a real invisibility cloak, and fantasy fans run out to update their Awesome Harry Potter Magic Things That Now Exist list (most recent addiction: the golden snitch.) But for all the disparate ongoing attempts to perfect stealth technology, it's still not possible to fully cloak an object from the naked eye.
Part of the problem, up until recently, has simply been a matter of scale. Scientists have known for years that metamaterials made from synthetic textiles can be used to to control the propagation of light. The artificial material bends light around an object, rendering it invisible to certain wavelengths. But, they could only fabricate the stuff in microscopic sizes.
Now, a team of researchers at the University of Central Florida, led by Debashis Chanda, have perfected a nanotransfer printing technique that makes it possible to create larger swaths of the metamaterial—about four by four inch squares. From there, multiple pieces can be stitched together with an automated tool to create a very large area of coverage, Chanda explained in an email.
It means the technology could finally have real-life, practical applications, he said. “Such large-area fabrication of metamaterials following a simple printing technique will enable realization of novel devices based on engineered optical responses at the nanoscale."
The nanotransfer printing technique creates metal/dielectric composite films, which are stacked together in a 3-D architecture with nanoscale patterns for operation in the visible spectral range. Control of electromagnetic resonances over the 3-D space by structural manipulation allows precise control over propagation of light. Following this technique, larger pieces of this special material can be created, which were previously limited to micron-scale size.
However, this doesn’t mean we can run out and start nanoprinting and stitching together huge cloaks to outfit the world’s first invisible army. Naturally, there's still a catch. Currently the process only bends light in the red and blue spectrum, not the full light spectrum, so it's not quite “invisibility." But Chanda believes that in a few years, the technology could lead to real-world applications in stealth tech, sensors, and camouflage—like exploring various infrared detectors, and hiding fighter jets from the enemy.
The research was funded by the Office of Naval Research, and now Chanda and co are pitching other organizations to fund further study, including the aerospace defense company Lockheed Martin. Meanwhile, in its race to develop cloaking technology on a par with the US military, China is bankrolling no less than 40 different invisibility cloaks currently in R&D.
Does it mean we should expect a real-world Harry Potter vanishing act? To the disappointment of kids everywhere up to no good, that won't be making the list anytime soon. “Not in the near future!” Chanda said.