Flat Lens a Thousand Times Thinner Than a Human Hair

The lens can be used to produce high-resolution images with a wide field of view. It can serve as a camera lens in smartphones and can be used in other devices that depend on sensors (high-resolution wide-angle selfie obtained using metalens.

A lens that is a thousand times thinner than a human hair has been developed in Brazil by researchers at the University of São Paulo’s São Carlos School of Engineering (EESC-USP). It can serve as a camera lens in smartphones or be used in other devices that depend on sensors.

“In the present technological context, its applications are almost unlimited,” Emiliano Rezende Martins, a professor in EESC-USP’s Department of Electrical Engineering and Computing and last author of a published paper on the invention, told Agência FAPESP.

The paper is entitled “On Metalenses with Arbitrarily Wide Field of View” and is published in ACS Photonics. The study was supported by FAPESP via a scholarship for a research internship abroad awarded to Augusto Martins, Ph.D. candidate and lead author of the paper.

The lens consists of a single nanometric layer of silicon on arrays of nanoposts that interact with light. The structure is printed by photolithography, a well-known technique used to fabricate transistors.

This kind of lens is known as a metalens. Metalenses has first developed ten years ago and achieved the highest resolution that is physically feasible, using an ultrathin array of tiny waveguides called a metasurface that bends light as it passes through the lens.

Based on the realization that in a conventional lens an increase in refraction index increases the field of view in proportion to the flatness of the lens, the authors designed a metalens to mimic a totally flat lens with an infinite refraction index, which could not be obtained with a conventional lens.

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