Inspired by the human eye, researchers have developed an adaptive metalens -- essentially a flat, electronically controlled artificial eye -- that automatically stretches to simultaneously focus and correct several factors that contribute to blurry images.

The adaptive metalens simultaneously controls for three of the major contributors to blurry images: Focus, astigmatism and image shift. The study, published in the journal Science Advances, demonstrates the feasibility of embedded optical zoom and autofocus for a wide range of applications including cell phone cameras, eyeglasses and virtual and augmented reality hardware. "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," said co-author Alan She from the Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS).

"It also shows the possibility of future optical microscopes, which operate fully electronically and can correct many aberrations simultaneously," the researcher added. To build the artificial eye, the researchers first needed to scale-up the metalens. Prior metalenses were about the size of a single piece of glitter. They focus light and eliminate spherical aberrations through a dense pattern of nanostructures, each smaller than a wavelength of light.

"Because the nanostructures are so small, the density of information in each lens is incredibly high," said She. To solve this problem, the researchers developed a new algorithm to shrink the file size to make the metalens compatible with the technology currently used to fabricate integrated circuits. In a paper recently published in Optics Express, the researchers demonstrated the design and fabrication of metalenses up to centimetres or more in diameter.

"This research provides the possibility of unifying two industries; semiconductor manufacturing and lens-making, whereby the same technology used to make computer chips will be used to make metasurface-based optical components, such as lenses," the researchers said. The researchers also demonstrated that the lens can simultaneously focus, control aberrations caused by astigmatisms, as well as perform image shift. Together, the lens and muscle are only 30 microns thick.