Technology 3 min read

Researchers Develop New Metalens For Low-Light Conditions

made widhana / Shutterstock.com

made widhana / Shutterstock.com

Researchers at the Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS) have developed a metalens for low-light conditions.

Metalenses are flat surfaces that use nanostructure to focus light. As simple as it sounds, these flat surfaces could one day replace the bulky curved lenses we currently use in optical devices.

Along with microscopy, metalens could revolutionize cameras, sensors, and displays. There’s just one thing.

So far, most of these metalenses are tiny, about the size of a piece of glitter. While this size is suitable for some applications, a larger lens is necessary for low-light conditions.

For example, applications such as virtual reality and imaging system onboard orbital satellites require that the lens be larger than the pupil.

Well, now such a metalens exist.

The SEAS researchers developed an all-glass, centimeter-scale metalens for low-light conditions at visible wavelength. What’s more, they used a conventional chip fabrication method to make the lens.

Speaking about the project, senior author of the study, Federico Capasso said:

“In the future, the same company can make both the chip and the lenses because both can be made using the same technology: lithography.”

Here’s how the researchers created the lenses.

Developing a Metalens for Low-Light Conditions

Before now, researchers were unable to mass-produce centimeter-scale metalenses at visible wavelengths.

That’s because they were either using electron lithography or i-line stepper lithography. While the former was time-consuming, the latter lacked enough resolution to pattern the required subwavelength-sized structure, said the researchers.

So, it became necessary to consider a new technique to mass-produce centimeter-scale metalens. That’s where deep-ultraviolet (DUV) projection lithography comes in.

It’s a common technique used to pattern fine lines and shapes in silicon chips that are in smartphones and computers. Now, it can produce many metalenses per chip, each consisting of millions of nanoscale elements.

The DUV process involves etching the nanostructure pattern directly on a glass surface. So, unlike the previous techniques, the researchers were able to save a lot of time.

According to the researchers, it is the first mass-producible, all-glass, centimeter-scale metalens in the visible spectrum.

Federico Capasso noted:

“This research paves the way for so-called wafer-level cameras for cell phones, where the CMOS chip and the metalenses can be directly stacked on top of each other with easy optical alignment because they are both flat.”

In their study, the researchers were only able to produce chromatic metalens for low-light conditions. That means all the different colors don’t focus on the same spot.

However, they are currently working on larger-diameter achromatic lenses.

Read More: Artificial Eye Created Using Metalens Tech and Synthetic Muscle

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Sumbo Bello

Sumbo Bello is a creative writer who enjoys creating data-driven content for news sites. In his spare time, he plays basketball and listens to Coldplay.

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