Artificial lens likened to human eye

The team from Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS) used a metalens – a flat surface that uses nanostructures to focus light – as the basis for its project, which the researchers say is the first of its kind.“This research combines breakthroughs in artificial muscle technology with metalens technology to create a tunable metalens that can change its focus in real time, just like the human eye,” one of the paper’s author’s Mr Alan She said.“We go one step further to build the capability of dynamically correcting for aberrations such as astigmatism and image shift, which the human eye cannot naturally do.”Metalenses focus light and eliminate spherical aberrations through a dense pattern of nanostructures, each smaller than a wavelength of light. Earlier metalenses were about the size of a single piece of glitter, which meant the team needed to scale the device up to build the artificial eye.The researchers also needed to adhere the large metalens to an artificial muscle without compromising its ability to focus light. To do this, the team chose a thin, transparent dielectric elastomer with low loss – meaning light travels through the material with little scattering – to attach to the lens.Together, the lens and muscle are only 30 microns thick, and the elastomer itself is controlled by applying voltage – as it stretches, the position of nanopillars on the surface of the lens shift.“All optical systs with multiple components have slight misalignments or mechanical stresses on their components that will always cause small amounts of astigmatism and other aberrations, which could be corrected by an adaptive optical elent,” She explained.“Because the adaptive metalens is flat, you can correct those aberrations and integrate different optical capabilities onto a single plane of control.”The researchers aim to further improve the functionality of the lens and decrease the voltage required to control it.