Invisibility........One Step Closer

This is incredible stuff indeed!

Invisibility might one day in the future no longer be just an optical illusion only for magicians and tricksters. Scientists and engineers in different parts of the world are working on developing fabrics and materials that can be seen through, much like the Invisibility cloak in Harry Potter.

Electronic engineers at the University of Pennsylvania are working on a real invisibility shield called a "plasmonic cover".The development works by preventing objects from reflecting and scattering light, could have widespread use in the military as it would be more effective than current stealth technology.

Similarly, researchers in Tokyo are developing a camouflage fabric that uses a comparable principle where the background is projected on to light-reflecting beads in the material. Such systems are, however, dependent on the viewer from which the object is being concealed being in the right position.

According to Dr Andrea Alu and Dr Nader Engheta, the engineers behind the project, the key is to reduce light scattering. Objects are visible because light bounces off them; if this can be prevented and if the objects did not reflect any light, they would become invisible. The "plasmonic screen" achieves this by resonating in tune with the illuminating light."Plasmons" are created when the electrons on the surface of a metallic material move in rhythm. The developers claim a shell of this material will reduce light-scatter to the extent that an object will become invisible, if the light’s frequency is close to the resonant frequency of these "plasmons". In this way, the scattering from the shell effectively cancels out the scattering from the object.

Experiments have shown that spherical or cylindrical objects coated with such shields do produce very little light scattering, which renders them nearly invisible. However, the cloak would have to be delicately tuned to suit each object it hides. Also, a specific shield may only work for one wavelength of light, rendering it invisible in, say, red light, but not in multi-wavelength daylight.

Another problem which has to be solved is that the effect would only work in daylight when the wavelength of the light being scattered is the same size as the object - meaning only tiny things can so far be hidden.

One of the labs in the University of Tokyo uploaded some interesting videos of their "quasi-invisivility" using a specific fablic and projector