Using invisibility to increase visibility

Nov 27, 2008

Research into the development of invisibility devices has spurred two physicists' thought on the behaviour of light to overcome the seemingly intractable problem of optical singularities which could soon lead to the manufacturing of a perfect cat's eye.

A research paper published in a New Journal of Physics' focus issue 'Cloaking and Transformation Optics' called 'The Transmutation of Singularities in Optical Instruments', written by Thomas Tyc, Masaryk University, and Ulf Leonhardt, the University of St. Andrews and Singapore National University, shows that it is possible to reflect light from all directions.

Cat's eyes and glow-in-the-dark clothing are effective because they send light back from where they came to either provide direction to a driver on the road or alert drivers of, say, a cyclist's presence but although this works well for light from some angles, it does not work well for all.

When light is shone through a glass of water with a straw in it and it appears as though the straw is bent, it is because the speed of light has been affected by the glass and the water that the light has been obstructed by. Physicists measure the effect that materials have on light using the refractive index, with 1 as the speed of light unobstructed in air, and, approximately, 1.5 as the point on the index when light meets glass and water.

What happens however when the material forces light down to zero or shoots it up to infinity on the refractive index? These are called optical singularities and have long been thought impossible to produce but it is what physicists need to understand to create a material that can reflect light from all directions and thereby create the perfect cat's eye.

Tyc and Leonhardt use ideas from one of the latest trends of optics called transformation optics to transmute the infinity mark on the refractive index into something more practical. Put simply, the scientists have developed a recipe of materials to create optical illusions – some can be used for invisibility devices, others to make things perfectly visible.

As Tyc and Leonhardt write, "Our method works for optical singularities which are the curse of physics, often seeming intractable, but we have found a way of transmuting optical singularities with just harmless crystal defects as a side-effect."

Applications will probably first appear in wireless technology and radar, for electromagnetic microwaves instead of light, because the required materials for electromagnetic microwaves are easier to manufacture.

The published version of the paper "Transmutation of Singularities in Optical Instruments" (T Tyc and U Leonhardt 2008 New J. Phys. 10 115038) is available online at stacks.iop.org/NJP/10/115038

Source: Institute of Physics

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User comments : 7

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srikkanth_kn
3.3 / 5 (7) Nov 27, 2008
A little image illustration would have been of help.
physpuppy
4 / 5 (6) Nov 27, 2008
A little image illustration would have been of help.


They probably have one, but it's of the invisible object.

See how well their technique works?
Smellyhat
5 / 5 (3) Nov 27, 2008
This article is not very well written. Most english speakers, of course, are not native to the language, and some allowances must be made for this. However, the article is mainly a review of basic science, poorly presented, with the actual news content restricted to a single sentence: "Tyc and Leonhardt use ideas from one of the latest trends of optics called transformation optics to transmute the infinity mark on the refractive index into something more practical." Actual information about this is sorely lacking.

And this "could soon lead to the manufacturing of a perfect cat's eye?" Really?

jeffsaunders
3 / 5 (6) Nov 27, 2008
I think the cats would appreciate a better eye.
out7x
2 / 5 (4) Nov 28, 2008
This is one of the worst written articles. Think refraction and diffraction.
Crossrip
not rated yet Nov 28, 2008
The type of reflective devices they are talking about would be ideal to place on bouys or sail boats to make them more visible on radar.
nevereverever
not rated yet Dec 01, 2008
I really likd 'The Invisible Man" TV show when I was a kid.

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