Undergraduate opens invisibility cloaking to the whole spectrum

Tue, 08/09/2011 - 6:04am

A light trajectory is shown against the distribution of the ?? values. The light ray enters the device, completes a loop, bounces off the mirror twice and leaves the cloak with its original direction restored (A). Panel (B) gives a closer view of the vicinity of the inner branch of the cloak. Objects placed within the white region are invisible.



The optical device, known as an 'invisible sphere', would slow down all of the light that approaches a potential cloak, meaning that the light rays would not need to be accelerated around the cloaked objects at great speeds?a requirement that has limited invisibility cloaks to work only in a specified region of the visible spectrum.




Under the guidance of Professor Ulf Leonhardt, Janos Perczel, originating from Hungary and reading Logic, Philosophy of Science and Physics at the University of St Andrews, acknowledged the huge potential of the invisible sphere and was able to fine-tune it so that it was a suitable background for cloaking.


The usual approach to designing an invisibility cloak works on the basis of bending light?using highly specific materials?around an object that you wish to conceal, thereby preventing the light from hitting the object and revealing its presence to the eye of the observer.




Light, however, can only be accelerated to a speed faster than it would travel in space under certain conditions, and this restricts invisibility cloaks to work in a limited part of the spectrum?essentially just one colour.








An Institute of Physics spokesperson said, "This new development opens up further possibilities for the design of a practical invisibility cloak?overcoming the problem of light speed that other advances have struggled to address and, very impressively, this significant advance was achieved by an undergraduate student."

Invisibility cloaking without superluminal propagation

Institute of Physics


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