Duke University engineers have created a new generation of lens that could greatly improve the capabilities of telecommunications or radar systems to provide a wide field of view and greater detail.

But the lens they fashioned doesn't look anything like a lens. While traditional lenses are made of clear substances - like glass or plastic - with highly polished surfaces, the new lens looks more like a miniature set of tan Venetian blinds.

The latest advance was made possible by the ability to fabricate exotic composite materials known as metamaterials. The metamaterial in these experiments is not so much a single substance, but the entire man-made structure which can be engineered to exhibit properties not readily found in nature.

The prototype lens, which measures four inches by five inches and less than an inch high, is made up of more than 1,000 individual pieces of the same fiberglass material used in circuit boards and is etched with copper. It is the precise arrangement of these pieces in parallel rows, that directs the rays as they pass through.

"For hundreds of years, lens makers have ground the surfaces of a uniform material in such a way as to sculpt the rays as they pass through the surfaces," said Nathan Kundtz, post-doctoral associate in electrical and computer engineering at Duke's Pratt School of Engineering. "While these lenses can focus rays extremely efficiently, they have limitations based on what happens to the rays as they pass through the volume of the lens.

"Instead of using the surfaces of the lens to control rays, we studied altering the material between the surfaces," Kundtz said. "If you can control the volume, or bulk, of the lens, you gain much more freedom and control to design a lens to meet specific needs."

The results of his experiments, which were conducted in the laboratory of senior researcher David R. Smith, the William Bevan Professor of Electrical and Computer Engineering, appeared as an advanced online publication of the journal Nature Materials. This is the first demonstration of what was thought to be theoretically possible.

"A close-up view of the new lens. (Credit: Duke University Photography)"

Source: Duke University