Invisibility cloaking in ‘perfect’ demonstration

SCIENTISTS have succeeded in “cloaking” an object perfectly for the first time, rendering a centimetre-scale cylinder invisible to microwaves.
Many “invisibility cloak” efforts have been demonstrated, but all have reflected some of the incident light, making the illusion incomplete.  A Nature Materials study has now shown how to pull off the trick flawlessly.
However, the illusion only works from one direction and would be difficult to achieve with visible light.  The idea of invisibility cloaking got its start in 2006 when John Pendry of Imperial College London and David Schurig and David Smith of Duke University laid out the theory of “transformation optics” in a paper in Science, demonstrating it for the first time using microwaves (much longer wavelengths than we can see) in another Science paper later that year. The papers sparked a flurry of activity to move the work on to different wavelengths - namely those in which we see. As the “Where’s my cloak of invisibility?” article points out, the field has moved on considerably since then. But no effort to date has been able to achieve the “perfect” cloaking that the theory originally described. The structures that can pull off this extraordinary trick of the light are difficult to manufacture, and each attempt has made an approximation to the theoretical idea that results in reflections. So someone would not see a cloaked object but rather the scene behind it - however, the reflections from the cloak would make that scene appear somewhat darkened.                  –BBC

on epaper page 11
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