|Aug 24, 2020|
Researchers develop flat lens a thousand times thinner than a human hair(Nanowerk News) 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,” says 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 (ACS Photonics, "On Metalenses with Arbitrarily Wide Field of View").|
|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.|
|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. (Image: Augusto Martins/USP)|
|According to Rezende Martins, metalenses have long faced the problem that the angle of view is extremely small (less than 1°). “One way to solve the problem is to combine metalenses, forming complex structures,” he said.|
|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.|
|“Our lens has an arbitrary field of view, which ideally can reach 180° without image distortion,” Rezende Martins said. “We’ve tested its effectiveness for an angle of 110°. With wider angles of view, light energy decreases owing to the shadow effect, but this can be corrected by post-processing.”|
|Combining metalenses prevents super-resolution, but the resolution obtained is sufficient for all conventional applications. Martins tested the metalens with a 3D printed camera and obtained high-resolution images with a wide field of view. “So far we’ve only succeeded in photographing in green, but in the months ahead we’ll upgrade the lens so that all colors are feasible,” he said.|
|Source: By José Tadeu Arantes, Fundação de Amparo à Pesquisa do Estado de São Paulo|
Subscribe to a free copy of one of our daily
Nanowerk Newsletter Email Digests
with a compilation of all of the day's news.
These articles might interest you as well: