Friday, August 15th, 2008

Towards a Super Lens -- Or Invisibility?

A scanning electron microscope image of a 3-D "fishnet" metamaterial that can achieve a negative index of refraction at optical frequencies. The alternating layers form small circuits that can bend light in unusual ways. Image by Jason Valentine, UC Berkeley

In nature, light passing from one material into another always bends, or is refracted, in the same direction. The effect of refraction is the reason it can be difficult to reach into water and pick up an object while watching from above the water -- the underwater object isn't exactly where it appears to be to your eye. The effect also makes it difficult to construct high precision lenses and optics for microscopes and lithographic equipment. Writing this week in both Science and Nature, researchers report that they've been able to create an artificial material, known as a metamaterial, that bends some wavelengths of light differently, causing it to refract it in the opposite direction.

If the researchers are able to expand the work to a wider range of wavelengths, such a material would provide an unprecedented level of control over the way light moves. By combining such a material with other optical materials, it might be possible to construct a lens with almost no distortion, allowing ultra-high-resolution imaging. Taking the research into the science fiction realm, the material could point the way towards the construction of a 'cloak of invisibility' that would bend light around an object, concealing it from an observer. In this segment, Ira talks with one of the researchers on the project about its potential and its limitations.