Using the human eye as a model, scientists from the Harvard John A. Paulson School of Engineering and Applied Sciences have successfully developed an adaptive metalens to assist with human vision. The new lens is a flat, electronically controlled artificial eye. The product – a metalens – can simultaneously control for three of the major contributors to blurry images. These vision issues are problems of focus, astigmatism (a type of refractive error in which the eye does not focus light evenly on the retina), and image shift.
A “metalens,” is a term for a special type of lens constructed on an extremely small, nanoparticle scale (thousands of times thinner than a human hair). A metalens uses nanofins, which are tiny structures, typically made of titanium dioxide, in order to bend wavelengths toward the metalens focal point.
To create the lens, a new algorithm was developed, taking advantage of artificial intelligence to help with design. This led to the perfection of methods that allowed the scientists to shrink the file size to make the metalens compatible with the technology commonly used to fabricate integrated circuits. Artificial intelligence also helped the researchers to find a means to fix the metalens to artificial muscle without affecting its ability to focus light.
The research has a number of potential technology uses, such as cell phone cameras, eyeglasses and virtual and augmented reality hardware. There is also a potential application for optical microscopes.
Commenting on the research, lead scientist Professor Alan She explains: “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.”
The scientist adds: “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.”
The research has been published in two papers. the first appears in Science Advances, titled “Adaptive metalenses with simultaneous electrical control of focal length, astigmatism, and shift”; and the second has been accepted by Optics Express, headed “Large area metalenses: design, characterization, and mass manufacturing.”
