Researchers at Cornell’s School of Applied and Engineering Physics and Samsung’s Advanced Institute of Technology have created a one-of-a-kind metallic lens, a metamaterial lens, which can be focused using tension instead of mechanically move its components.
The proof of concept opens the door to a range of compact varifocal lenses for possible use in many imaging applications such as satellites, telescopes and microscopes, which traditionally focus light using curved lenses that s ‘adjust using mechanical parts. In some applications, moving traditional glass or plastic lenses to vary the focal length is simply not practical due to space, weight or size considerations.
Metalenses are flat arrays of nanoantennas or resonators, less than a micron thick, which act as focusing devices. But until now, once a metal was made, its focal length was difficult to change, according to Melissa Bosch, a doctoral student and first author of an article detailing research in the American Chemical Society’s journal Nano Letters.
The innovation, developed as part of the collaboration between researchers at Samsung and Cornell, was to fuse a metalene with well-established liquid crystal technology to tailor the local phase response of the metalens. This allowed researchers to vary the focus of metals in a controlled manner by varying the voltage applied across the device.
“This combination worked as we hoped and expected,” said Bosch, who works in the lab of Gennady Shvets, professor of applied physics and engineering and lead author of the article. “The result was an electrically adjustable ultra-thin lens capable of continuous zoom and a total focal length shift of up to 20%.
Samsung researchers hope to develop the technology for use in augmented reality glasses, according to Bosch. She sees many other possible applications such as replacing optical lenses on satellites, spacecraft, drones, night vision goggles, endoscopes and other applications where saving space and weight are of the utmost importance. priorities.
Maxim Shcherbakov, postdoctoral associate at the Shvets lab and corresponding author of the paper, said researchers have made progress in associating liquid crystals with nanostructures over the past decade, but no one has applied this idea to lentils. Now the group plans to continue the project and improve the capabilities of the prototype.
“For example,” said Shcherbakov, “this lens works on one wavelength, red, but it will be much more useful if it can work on the entire color spectrum – red, green, blue.”
The Cornell research group is currently developing a multi-wavelength varifocal version of the metalens using the existing platform as a starting point.
“The optimization procedure for other wavelengths is very similar to that for red. In some ways the most difficult step is already over, now it’s just a matter of building on the work already done, ”Bosch said.
This work was supported by the Global Research Outreach program of the Samsung Advanced Institute of Technology and, in part, by the Cornell Center for Materials Research with funding from the National Science Foundation and the US Office of Naval Research.
Chris Dawson is a writer for the College of Engineering.