Researchers from Cornell University’s School of Applied and Engineering Physics and Samsung’s Advanced Institute of Technology have created a first-of-its-kind metalens–a metamaterial lens–that may be focused using voltage instead of mechanically moving its components.
The proof of concept opens the door to a range of compact varifocal lenses for possible use in many imaging programs such as satellites, telescopes and microscopes, which traditionally focus lighting utilizing curved lenses that adjust using mechanical pieces. In some applications, moving traditional plastic or glass lenses to vary the focal distance is just not practical because of space, size or weight concerns.
Metalenses are horizontal arrays of nano-antennas or resonators, less than a micron thick, that act as focusing apparatus. But before now, once a metalens was made, its own focal length was hard to change, according to Melissa Bosch, doctoral student and first author of a paper detailing the research from the American Chemical Society’s journal Nano Letters.
The invention, developed in the collaboration between Samsung and Cornell researchers, involved merging a metalens with the well-established technology of liquid crystals to tailor the neighborhood phase reaction of the metalens. This enabled the investigators to vary the focus of the metalens in a controlled way by changing the voltage applied across the machine.
“This combination worked out as we hoped and predicted it would,” said Bosch, that operates in the lab of Gennady Shvets, professor of applied and engineering physics and senior author of the paper. “It resulted in an ultrathin, electrically tunable lens capable of continuous zoom and up to 20% total focal length shift.”
Samsung investigators are hoping to develop the technology for use in augmented reality glasses, according to Bosch. She sees many other possible applications such as replacing the optical lenses on satellites, spacecraft, drones, night-vision goggles, endoscopes and other applications where saving space and weight are priorities.
Maxim Shcherbakov, postdoctoral associate in the Shvets laboratory and corresponding author of the paper, stated that researchers have made progress in devoting liquid crystals into nanostructures for the last ten years, however, nobody had implemented this idea to lenses. The group intends to continue the job and improve the model’s capabilities.
“For instance,” Shcherbakov stated,”this lens works at a single wavelength, red, but it will be much more useful when it can work across the color spectrum–red, green, blue.”
The Cornell research group is now developing a multiwavelength varifocal variant of this metalens utilizing the present platform as a beginning point.