MIT Creates Lens for Radio Waves

Metamaterials are, by their very definition, awesome. The first sentence of the Metamaterials entry on Wikipedia reads:

Metamaterials are artificial materials engineered to have properties that may not be found in nature.

And as should be expected of materials that are supernatural, they can endow objects with properties that seem uncanny. In recent years, researchers have used metamaterials to create “invisibility cloaks” and “super lenses” capable of focusing light to such a degree that objects on the nanoscale can be imaged.

In a paper recently published in the Journal of Applied Physics, MIT grad student Isaac Ehrenberg describes another set of interesting properties associated with his metamaterial concave lens.

"Usually when we think of a lens we imagine a convex shape that takes a broad area of light and focuses it into a beam as it passes through the lens’ material. Ehrenberg’s lens “exhibits a property called negative refraction, bending electromagnetic waves — in this case, radio waves — in exactly the opposite sense from which a normal concave lens would work.”

But how exactly was Ehrenberg able to achieve this feat?

One of the reasons that metamaterials display such unusual behaviors is due to the shape of the individual objects that are arranged to make up their whole. Each metamaterial has an “elemental” geometry that is unique to the properties it displays.

To create the geometry for his radio lens, Ehrenberg turned to 3D printing to assemble the minute intricacies of his design. MIT describes the process:

“Ehrenberg utilized 3-D printing, building a lens layer by intricate layer from a polymer solution. He then washed away any residue with a high-pressure water jet and coated each layer with a fine mist of copper to give the lens a conductive surface.”

By using 3D printing, Ehrenberg created a lens that was extremely lightweight, which increased the new materials potential usefulness. According to MIT, “The device, which weighs less than a pound, may be used to focus radio waves precisely on molecules to create high-resolution images — images that are currently produced using bulky, heavy and expensive lenses. Ehrenberg says that such a lightweight device could also be mounted on satellites to image stars and other celestial bodies in space, 'where you don’t want to bring up a hefty lens.'”