[extropy-chat] A Perfect lens

[John K Clark]

There is a very interesting article in the March 17 issue of Science about
a material with a negative refractive index that could be used to make a
perfect lens. It might be possible to use this material in the next
generation of MRI machines to obtain vastly more detailed pictures. If they
can make such a lens work for light and not just microwaves in might even
have applications in Photo Lithography to make better computer chips.

John K Clark      jonkc at att.net

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Lens Once Deemed Impossible Now Rules the Waves

For centuries, microscopes, eyeglasses, and magnifying glasses have been
limited by the laws of optics: No matter how good their lenses, details
smaller than a wavelength of light are irretrievably lost. Undaunted,
physicists have built a different breed of lens with the potential for
perfect resolution.

The new lens, which George Eleftheriades and Anthony Grbic of the University
of Toronto describe in an upcoming issue of Physical Review Letters, focuses
microwaves--long-wavelength radiation that falls next to radio waves in the
electromagnetic spectrum. By embedding a wire grid studded with capacitors
and inductors in a flat plane of plastic, the researchers created a lens
with a so-called negative refractive index, also called a left-handed lens.
Waves traveling through it bend in the opposite direction than they would in
a conventional material.

The left-handed lens achieves super-resolution by resurrecting waves that
carry the subwavelength details of an object. Such waves usually fizzle out
before they pass through a lens. But the Toronto group's lens traps and
amplifies them, allowing it to distinguish objects just 1/6 of a microwave
wavelength apart.

The new technique "smashed the barrier; it crashed through the glass
ceiling," says John Pendry, a physicist at Imperial College London. In 2000,
Pendry predicted that left-handed materials would make possible marvels such
as completely flat lenses with perfect resolution and zero loss (Science, 10
November 2000, p. 1066). In February, physicists at the Institute for
Theoretical and Applied Electromagnetics in Moscow announced a
super-resolving lens, but their technique required the object to be almost
touching the lens, making it impractical for real-life applications. The new
lens overcomes that limitation.

Eleftheriades dreams of applying the left handed lens to medical imaging.
"If you were to scale down the frequencies of a MRI (20 megahertz), you
could place the human body 1 meter away and still get super-resolution," he
says- a vast improvement over current instruments.


--KIM KRIEGER