Friday, 23 May 2008
Now You See It. Now You Don't.
My first view of an 'Invisibility Cloak' was @ the NextFest 2004, in San Francisco.
However, things are thundering ahead.
Researchers at Toyama University announced that they have formulated a ‘Perfect invisible cloak.’
The invisible cloak generates no reflection or phase delay at all even when an electromagnetic wave passes through it. It was developed with the use of an artificial dielectric material called ‘left-handed metamaterial, which has a negative refractive index.
It is predicted that the use of left-handed metamaterials makes electromagnetic control devices available. Some examples of such devices are a lens that reflects no light and a lens that can provide a perfect focal point.
They are believed to be difficult to produce with the existing materials. The latest development relates to one of these control devices.
Here, an invisible cloak refers to a block object with a void in the core or centre, which is designed such that a plane electromagnetic wave with a certain frequency irradiated at this object goes around the void and reaches behind the object.
In particular, the object may be called ‘the perfect visible cloak’ when the electromagnetic wavefront becomes planar again after passing through the object and the amplitude and the phase of the resultant plane wave completely coincide with those of the wavefront obtained when there is no object.