Invisibility cloaks have been the stuff of legend for millennia. From the mantle of Welsh fairy-tales to the Japanese kakuremino, people the world over have imagined fashioning a magical fabric that can hide anything in plain sight. Closer to home, Exeter alumna JK Rowling famously included an invisibility cloak in her fictional trinity of magical objects – the Deathly Hallows.
Thanks to new scientific breakthroughs at Queen Mary University of London (QMUL), this iconic object of folklore may be a step closer to reality. Researchers at the School of Electronic Engineering have succeeded in disappearing an object using nano-particles in a composite material.
While we may not have reached Harry Potter levels of invisibility yet, the principles behind the magic are similar. To make an object invisible, it should be indistinguishable from its background. The cloak should affect any wavelength or colour of light to fully disappear the object from the viewer.
The cloaking device at QMUL allows curved surfaces to appear flat to electromagnetic waves. By applying seven distinct layers of the composite material, the resultant structure is able to cloak an object that would have caused waves to be scattered, and therefore be detected.
Co-author, Professor Yang Hao from QMUL’s School of Electronic Engineering and Computer Science, said: “The design is based upon transformation optics, a concept behind the idea of the invisibility cloak.
“Previous research has shown this technique working at one frequency. However, we can demonstrate that it works at a greater range of frequencies making it more useful for other engineering applications, such as nano-antennas and the aerospace industry.”
“iNVISIBILITY CLOAKS ARE TRANSITIONING FROM THEIR FICTIONAL ORIGINS… AND MAY FIND APPLICATION IN INDUSTRY WITHIN A MATTER OF YEARS…”
The principles behind this design can be applied elsewhere, from acoustic to optics, to control of any kind of electromagnetic surface waves. Invisibility cloaks are transitioning from their fictional origins, being demonstrated with the laws of physics, and may find application in industry within a matter of years, with objects being able to be placed in locations that would have previously caused the waves to scatter.
These claims are, of course, to be taken with a pinch of salt. The materials used in these research experiments are often highly dispersive and face the challenge of resulting in strong refraction. Also, some light may still be absorbed by the material and object, so the object is slightly opaque and therefore detectable. We’re still a far throw from donning invisibility cloaks ourselves. Perfecting the process is still something of a dark art, but this research is an important step towards real world application in industry.
