Engineers Design a Wide-Angle Lens That is Completely Flat

A team of engineers from MIT and the University of Massachusetts at Lowell has designed a fisheye lens that’s completely flat.

It is the first wide-angle lens that produces crisp, 180-degree panoramic images. The design is a type of “metalens,” a wafer-thin material patterned with microscopic features that work together to manipulate light in a specific way.

The team has published their results in journal Nano Letters.

Problem
We all know that to take a panoramic image, we need a special lens. These special ultra-wide-angle lenses are made from many pieces of curved glass. Their design makes wide-angle lenses bulky and often costly to produce. This is a big problem and with the current research we can wipe out this problem completely.

What is Metalens?
Metalenses are flat surfaces that use nanostructures to focus light. These simple, flat surface lenses could replace bulky, curved lenses currently used in optical devices

In the current design, the lens consists of a single flat, millimeter-thin piece of glass covered on one side with tiny structures that is capable of precisely scattering incoming light to produce panoramic images. This new lens currently works in infrared region but researchers claim that it can be used in visible region as well.

“This design comes as somewhat of a surprise because some have thought it would be impossible to make a metalens with an ultra-wide-field view,” says Juejun Hu, associate professor in MIT’s Department of Materials Science and Engineering. “The fact that this can actually realize fisheye images is completely outside expectation.

“This isn’t just light-bending—it’s mind-bending.”

Metalens is not a new thing. Previously, scientists have designed metalenses that produce high-resolution and relatively wide-angle images of up to 60 degrees. But the problem is to increase the wideness, it required extra components to produce a perfect image which again makes it bulky. The current design has solved this problem as well.

The team came up with a simple design that didn’t require additional components. Their new metalens is a single transparent piece made from calcium fluoride with a thin film of lead telluride deposited on one side. The team then used lithographic techniques to carve a pattern of optical structures into the film.

“Currently, all 3-D sensors have a limited field of view, which is why when you put your face away from your smartphone, it won’t recognize you,” says Tian Gu, on of the engineers. “What we have here is a new 3-D sensor that enables panoramic depth profiling, which could be useful for consumer electronic devices.”

Journal Reference:
Mikhail Y. Shalaginov, Sensong An, Fan Yang, Peter Su, Dominika Lyzwa, Anuradha M. Agarwal, Hualiang Zhang, Juejun Hu, and Tian Gu Single-Element Diffraction-Limited Fisheye Metalens Nano Letters DOI: 10.1021/acs.nanolett.0c02783

Press Release: MIT