Harvard has reported a breakthrough flat artificial eye just 30 microns in depth which can exceed the capabilities of the human eye. The technology was build on 'metalens' technology by adding electrically-controlled flexible muscles and could make a real impact in all manner of optical fields, including those in cameras, telescopes, microscopes, glasses and even virtual reality.
The prototype device can make simultaneous adjustments for image focus, image shift and astigmatism, all of which can cause blurred images and which are adjustments beyond what your own eye can do. The technology will also be able to focus in real time, just as your eye can.
"All-optical systems 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 element," explains Alan She, an author of the research. "Because the adaptive metalens is flat, you can correct those aberrations and integrate different optical capabilities onto a single plane of control."
The metalens that Alan She refers to is a flat silicon nanostructure that focuses light, but this eye goes further by adding surrounding artificial muscle, which posed some real challenges to the team.
The first challenge was to make the metalens much bigger, as earlier prototypes were no larger than a piece of glitter. Scale that up to a 1-cm lens and the team discovered that the data needed to describe the design of the lens could amount to terabytes, thanks to the complexity of the nanostructures involved in the design.
To resolve the problems, the team developed an algorithm capable of describing the lens production, which reduced the data down to manageable size and made it compatible with the technology used to make integrated circuits. If the lenses could be made similar to circuits, as the research suggests, this is a considerable boon for the commercial viability of the technology.
The next challenge the team had to overcome was to attach an artificial muscle to the lens without significantly compromising its optical performance. The team chose a dielectric elastomer – which is an elastic polymer which could be controlled by applying electricity via carbon nanotube electrodes. The researchers identified an elastomer which allowed light to pass through without much loss due to scattering.
The research was carried out at the Harvard John A. Paulson School of Engineering and Applied Sciences. The team's paper has been published in Science Advances.