If the sensors keep evolving, this is not the case with objective lenses which have been more or less the same for a decade. This is likely to change in the near future.
Remember, in 2007 the first iPhone came out with a 2 megapixel camera. In addition, there was only the rear camera, no photo module on the front to take a selfie. Today, you find multiple cameras in front of and behind the phone and some sensors go up to 108 megapixels. This is particularly the case with the larger sensor of the Samsung Galaxy S21 Ultra.
If the size of the sensors and the number of pixels have continued to increase in recent years, not to mention improvements in image processing, the goals that are paramount to a quality image have fundamentally not changed.
A new company called Metalenz, which recently came out of the shadows, is looking to create a technological breakthrough with phone cameras. It is a single flat lens that uses a technology called an optical metasurface. A camera with this kind of lens can produce an image of the same, if not better, quality than with a conventional lens. It captures more light, and can allow new forms of sensors while taking up less space.
A flat lens
What is the principle ? To understand this, it is important to review the operating mode of our conventional sensors. A modern photo module, like the one on the iPhone 12 pro for example, has 3 lenses on the back of the device, but each has several lenses placed on top of each other. The iPhone’s main sensor currently uses a 7-lens lens. A multi lens system is more efficient than its counterpart with a single lens. At each successive stage, the image gains in sharpness and clarity.
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Multiplying the lenses allows manufacturers to compensate for irregularities introduced by a single element such as chromatic aberration or distortion. In return, this requires more vertical space in the camera module. This is one of the main reasons for the presence of a protrusion on the back of our phones. It also tends to thicken as we add optical zooms that require more space.
Some manufacturers like Samsung have even come to create optics similar to periscopes in order to allow greater zooming capacity. If progress on lenses has been made, there have been no major revolutions in the field over the past ten years.
This is where Metalenz comes in. Instead of using stacked plastic or glass lenses, the company developed a system that uses a single lens built on a matrix between 1 × 1 and 3 × 3mm. Looking at her under the microscope, we can distinguish nanostructures measuring one thousandth of the width of a human hair. These nanostructures bend light in a way that corrects many shortcomings of a single lens system.
The core of this technology emerged from a decade of research when co-founder and CEO Robert Delvin was working on his PhD 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 resembling millions of circles of different diameters. “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 we can bend and shape the light just by changing the diameters of those circles,” Devlin says.
The resulting image is as sharp as that of a multi-lens sensor. Nanostructures take care of reducing or eliminating the aberrations common to traditional cameras. This design does not only reduce the space occupied. Delvin states thata Metalenz lens is able to deliver more light to the sensor allowing for a brighter and sharper image.
Another big advantage. The company has partnered with two leading semiconductor companies (currently capable of producing a million arrays per day), which means the optics would be made in the same foundries that make much of the consumer device. and industrial. An important asset in simplifying the supply chain.
New forms of sensors
The company will go into mass production by the end of the year. Its first application will be for 3D smartphone sensors. Metalenz has not yet revealed any client names. Delvin explains that current 3D sensors like the one used by Apple’s FaceID use a laser to scan the face and therefore consume a lot of energy. Since a Metalenz lens is able to deliver more light to the sensor, he states that it could help reduce the consumption of the device. Another good news? The lens taking up much less space, it could be placed directly under the screen glass and would allow manufacturers to eliminate the notch that clutters the screen.
Applications could even go beyond the smartphone world. The technology could be applied to the medical field, for virtual or augmented reality devices and even automotive cameras. In short, wherever the need for miniaturization of an optical sensor arises.
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Take the example of spectroscopy. A spectrometer precisely defines the wavelengths of light that it receives. In the medical field, it is particularly useful for detecting certain molecules in the blood. As metasurfaces collect the equivalent of an “optical stack in a single surface”, Delvin says that with the right sensor and a Metalenz lens, your smartphone could do the job.
“You can actually look at the chemical signature of the fruit with a spectrometer and tell if it’s ripe,” says Devlin. “It’s not just a picture anymore, you are actually accessing all kinds of different forms of sense, seeing and interacting with the world, getting a whole new set of information in the cell phone. “
Source : Arstechnica
Romain "Nemrod" Vandevelde