‘Invisibility carpet’ hides ‘large’ objects

LONDON - For the first time, physicists have built an ‘invisibility carpet’ that hides objects large enough to be seen with the naked eye.

Two independent groups have built transparent ‘carpet cloaks’, made from calcite crystals, that lie over the object to be hidden.

Carpet cloaks render covered objects invisible by bending light rays as they enter the cloak and then when they exit it - after they have bounced off the hidden object.

The light is deviated in such a way that the rays seem to have been reflected directly from the ground underneath the object - as though the object was not there.

To build such a cloak you need a material that will bend the incoming and outgoing light rays by different amounts - determined by the dimensions of the object underneath, explains Baile Zhang, an optical engineer at the Singapore-MIT Alliance for Research and Technology (SMART) Centre in Singapore, who designed one of the cloaks.

Calcite is perfect for the job because the speed at which polarized light passes through it depends on the crystal’s orientation.

So by sticking together two pieces of crystal, it is possible to create a cloak that bends incoming and outgoing light by the desired amount.

“The fact that calcite’s optical properties depend on orientation is usually a disadvantage in making devices, but I realized we could actually exploit it to our advantage,” Nature quoted Baile Zhang as saying. (ANI)