-- 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.
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.
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.
"While these experiments were conducted in two dimensions, the design should provide a good initial step in developing a three-dimensional lens," Smith said. "The properties of the metamaterials we used should also make it possible to use infrared and optical frequencies."
The researchers say a single metamaterial lens could replace traditional optical systems requiring vast arrays of lenses and provide clearer images. They could also be used in large-scale systems such as radar arrays to better direct beams, a task not possible for traditional lenses, which would need to be too large to be practical.
Recognizing the limitations of traditional lenses, scientists have long been investigating other options, including those known as gradient index (GRIN) lenses. These are typically clear spheres, and while they have advantages over traditional lenses, they are difficult to fabricate and the focus point is spherical. Additionally, because most sensing systems are oriented in two dimensions, the spherical image doesn't always translate clearly on a flat surface.
The new lens, however, has a wide angle of view, almost 180 degrees, and because its focal point is flat, it can be used with standard imaging technologies. The latest experiments were conducted with microwaves, and the researchers say it is theoretically possible to design lenses for wider frequencies.
"We've come up with what is in essence GRIN on steroids," said Smith
David R Smith Group at Duke