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June 25, 2006

Metamaterials background, superlens, super optical microscopes and other new capabilities

Metamaterials are artificially created substances that scientists essentially tune to respond to electromagnetic waves in ways that natural substances do not. The atoms and molecules of the actual materials with what look like micro- or nano-circuits. They look like little loops and wires. The architecture of the material creates new properties that its parent material doesn't have.

Xiang Zhang created a superlens and he is working to create improved versions that will revolutionize optical microscopes (going to 6 times smaller than optical wavelengths or less). With current optical microscopes, scientists can only make out relatively large structures within a cell, such as its nucleus and mitochondria. With a superlens, optical microscopes could one day reveal the movements of individual proteins traveling along the microtubules that make up a cell’s skeleton, the researchers said.

Scanning electron and atomic force microscopes are now used to capture detail down to a few nanometers. However, such microscopes create images by scanning objects point by point, which means they are typically limited to non-living samples, and image capture times can take up to several minutes.

"Optical microscopes can capture an entire frame with a single snapshot in a fraction of a second," said Fang, who is now an assistant professor of mechanical engineering at the University of Illinois at Urbana-Champaign. "That opens up nanoscale imaging to living materials, which can help biologists better understand cell structure and function in real time, and ultimately help in the development of new drugs to treat human diseases."

The key to the superlens is its ability to significantly enhance and recover the evanescent waves that carry information at very small scales. This enables imaging well below the diffraction limit."

Notably, no lens is yet able to completely reconstitute all the evanescent waves emitted by an object, so the goal of a 100-percent perfect image is still out there. However, (a paper looking at limitations of superlens) many scientists believe that a true perfect lens is not possible because there will always be some energy absorption loss as the waves pass through any known material.

More on the recent discussions about using metamaterials to create invisibility or cloaking.

Understanding metamaterials involves understanding the new physics of optics, electromagnetics and materials that it reveals

Some other technology that is likely to result from mastery of metamaterials. DVDs that hold more than 10 times the data of even the next-gen Blu-ray and HD-DVD discs. Ultrasound with super-fine resolution capable of detecting disease in unborn babies. A microscope powerful enough to see inside human cells. Extending optical lithography for semiconductors. Faster fiber optic communication. In the long run, this line of research could lead to even higher resolution imaging for distant objects. This includes more detailed views of other planets as well as of human movement through surveillance satellites.

David Smiths a prolific scientist involved in metamaterials

The July 2006 scientific American, has an article by David Smith that discusses the history of metamaterials and the new physics that has resulted from understanding metamaterials

Negative Index refraction homepage An introduction to negative index refraction.

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