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.
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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 were first developed ten years ago and achieve 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.
https://phys.org/news/2020-08-flat-lens-thousand-thinner-human.html