New lens technology set to relaunch phone cameras

The camera of the first iPhone in 2007 was only 2 megapixels. And there was only one rear camera; there wasn’t even a face-to-face selfie. Today you’ll find multiple cameras on the front and back of phones, some of them with sensors up to 108 megapixels, like the larger camera in Samsung’s Galaxy S21 Ultra.

But while the sensor size and megapixel count of smartphone cameras have grown dramatically over the past decade – not to mention improvements in computer photography software – the lenses that help take pictures remain basically unchanged.

A new company called Metalenz, now emerging from stealth mode, is looking to disrupt smartphone cameras with a single flat lens system that uses a technology called optical metasurfaces. A camera built around this new lens technology can produce an image of the same quality if not better than traditional lenses, collect more light for brighter photos, and may even enable new forms of detection in phones, while taking up less space.

A flat lens

How it works? Well, first of all, it is important to understand how the camera lenses of phones work today. The imaging system on the back of your smartphone may have multiple cameras – the latest iPhone 12 Pro has three cameras on the back – but each camera has multiple lenses or lens elements stacked on top of each other. . The aforementioned iPhone 12 Pro’s main camera sensor uses seven lens elements. A multiple lens design like the iPhone’s is superior to a single lens setup; As light passes through each successive lens, the image becomes sharper and clearer.

“Smartphone optics today consist of four to seven lenses,” says Oliver Schindelbeck, head of innovation at optics manufacturer Zeiss, which is known for its high-quality lenses. “If you have a single lens element, just by physics, you will have aberrations such as distortion or scatter in the image.”

More lenses allow manufacturers to compensate for irregularities such as chromatic aberration (when colors appear on the fringes of an image) and lens distortion (when straight lines appear curved in a photo). However, stacking multiple lens elements on top of each other requires more vertical space inside the camera module. This is one of the many reasons the camera “bump” on smartphones has grown bigger and bigger over the years.

“The more lens elements you want to fit into a camera, the more space it needs,” says Schindelbeck. Other reasons for the size of the bump include larger image sensors and more cameras with zoom lenses, which need more space.

Phone makers like Apple have increased the number of lens elements over time, and while some, like Samsung, are now bending optics to create “periscope” lenses for greater zoom capabilities, companies generally stuck with the proven stacked lens element. system.

“The optics got more sophisticated, you added more lens elements, you created powerful aspherical elements to get the space reduction needed, but there hasn’t been a revolution in the last 10. years in this field ”, explains Schindelbeck.

Metalenz overview

This is where Metalenz comes in. Instead of using plastic and glass lenses stacked on an image sensor, Metalenz’s design uses a single lens built on a slice of glass with a size between 1×1 and 3×3 millimeters. Look very closely under a microscope and you will see nanostructures measuring a thousandth the width of a human hair. These nanostructures bend light rays in a way that corrects many shortcomings of single lens camera systems.

The core technology was formed over a decade of research when co-founder and CEO Robert Devlin was working on his doctorate. at Harvard University with renowned physicist and Metalenz co-founder Federico Capasso. The company was separated from the research group in 2017.

Light passes through these patterned nanostructures, which look like millions of circles with different diameters on a microscopic level. “Just like a curved lens speeds up and slows down light to bend it, each of them allows us to do the same thing, so that we can bend and shape the light just by changing the diameters of those circles,” says Devlin.

The resulting image quality is just as crisp as what you would get from a multi-sensor system, and nanostructures do the job of reducing or eliminating many of the image degradation aberrations common to traditional cameras. And the design doesn’t just save space. Devlin says that a Metalenz camera can deliver more light to the image sensor, allowing for brighter, sharper images than what you would get with traditional lenses.

Another advantage? The company has formed partnerships with two leaders in semiconductors (who can currently produce one million Metalenz “chips” per day), which means that the optics are made in the same foundries that make consumer devices and industrial – an important step in the simplification of the supply chain.

New forms of detection

Metalenz will go into mass production towards the end of the year. Its first application will be to serve as a lens system of a 3D sensor in a smartphone. (The company did not give the name of the phone’s manufacturer.)

Devlin says current 3D sensors, like Apple’s TrueDepth Camera for Face ID, actively light up a scene with lasers to scan faces, but this can drain a phone’s battery life. Since Metalenz can bring more light to the image sensor, he claims it can help save power.

Other good news? If it’s a 3D sensor on the front of a phone for facial authentication, Devlin says the Metalenz system can eliminate the need for a bulky camera notch protruding into the screen, like that of current iPhones. The amount of space saved by forgoing traditional lens elements will allow more phone makers to place sensors and cameras under a device’s glass screen, which we’ll see more of this year.

Devlin says Metalenz’s apps go beyond smartphones. The technology can be used in everything from healthcare instruments, to augmented and virtual reality cameras, to automotive cameras.

Take the example of spectroscopy. A spectrometer is used to finely detect different wavelengths of light, and it is commonly used in medical assays to identify particular molecules in the blood. Since metasurfaces allow you to reduce “a table of optics into one surface,” Devlin says you can insert the right sensors into a smartphone with Metalenz to do the same type of work.

“You can actually look at the chemical signature of the fruit with a spectrometer and tell if it’s ripe,” says Devlin. “It’s really not just a picture anymore, you actually access all kinds of different forms of meaning, and you see and interact with the world, getting a whole new set of information in the cell phone.”

This story originally appeared on wired.com.