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New metalens technology from Harvard engineers could bring an end to many common vision problems. guvendemir/iStock
The future just got radically brighter for all those of us who weren't born with perfect vision. Thanks to breakthrough research from Harvard scholars at the John A. Paulson School of Engineering and Applied Sciences (SEAS), a tunable metalens that works in conjunction with current standards in artificial muscle technology can change its focus in real-time, very much like the natural human eye. The flashpoint in this development is the extra step the researchers have taken to enable the metalens to automatically correct for common aberrations in human vision.
The science of seeing straight
Blurry images in vision are generally attributable to one of three factors, or a combination of the three: astigmatism, image shift, and focus. By marrying a highly adaptive metalens to an artificial muscle, the Harvard SEAS researchers have effectively created an artificial eye that can be electronically controlled. Each of the elaborate systems of nanostructures that help metalenses eliminate spherical aberrations is more minuscule than a single wave of light. Due to the Lilliputian size of these lenses, the density of information per nanostructure is astronomical.
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The process of developing an artificial eye
While metalens technology is not necessarily a new wave concept in science, this project faced the indelible challenge of ramping up the capability options while reducing or at least maintaining a nanostructure size that rarely exceeds a single speck of glitter. Attempting to size up a lens of 100 microns to even a centimeter creates a girth of information needed to describe the lens that is 10,000 times the size of the original 100 microns. This leads to giga- and terabyte-sized files and the purpose of anything nano-based is to make things ever-smaller, not bigger, obviously.
To sidestep this problem, the Harvard analysts concocted a whole new algorithm and one that worked in strong compatibility with the technology governing basic integrated circuits. This meant that they could now generate a metalens of a centimeter or more in diameter, and, as a bonus, marry the lens-making industry to that of semiconductor manufacturing. Metasurface lens and computer chips now had something in common that appears to be beneficial to us all.
All that was left after this breakthrough was to attach the new metalens to a dielectric elastomer actuator--otherwise known as an artificial muscle, for which they enlisted the aid of David Clarke, Extended Tarr Family Professor of Materials at SEAS. Likening the process to his work with early scanning electron microscopes in the 1960s and utilizing voltage to control the elastomer, Clarke helped the team achieve a muscle and lens combination that is a shockingly-small 30 microns thick.
Watch the following video to hear Federico Capasso, key researcher in this study, talk more about the business of generating flat lenses.
Commercial possibilities and medical applications
Thinking that your eyeglasses might one day contain tiny, electronically-operated microscopes which correct your vision struggles automatically would have seemed like a Matrix-esque level of modernity not too many years ago. An adaptive optical element like this could reinvent many common approaches to human naturally-occurring vision problems. While the feasibility of alleviating a wide range of common vision problems is alluring enough, the commercial applications for this metalens stretch far into futuristic fields of interest. The potential for implanting optical zoom and autofocus capability into virtual and augmented reality hardware alone could spell huge gains in areas as diverse as homeland security and gaming.