Korean researchers shrink augmented reality lenses to fit everyday eyewear
The top picture shows a conceptual diagram of how augmented reality glasses overlay virtual images onto the real world using a microdisplay and dual metasurface waveguides. Bottom left is the AR glasses prototype, and bottom right is a side view of the 1.5-millimeter-thick waveguide showing a spacer between its red-green and blue-green layers. Courtesy of Pohang University of Science and Technology
New technology from POSTECH, Samsung keeps digital text bright and readable even in sunlight
Researchers in Korea have developed an ultrathin optical lens system that keeps digital images bright and legible even in direct sunlight, overcoming one of the main engineering hurdles preventing augmented reality glasses from looking and feeling like ordinary eyewear.
The joint team from Pohang University of Science and Technology (POSTECH) and Samsung Research built a prototype featuring a 1.5-millimeter-thick waveguide—the transparent channel that guides light from a tiny projector into the wearer’s eye—using engineered nanostructures called metasurfaces. The findings were published Thursday in the journal Nature, according to the Ministry of Science and ICT.
For years, technology giants from Meta and Apple to Google and Samsung have raced to build lightweight smart glasses capable of overlaying turn-by-turn directions, translations and messages onto the real world. However, engineers have struggled with a stubborn trade-off: widening the viewing zone so a user can glance around without losing the image typically causes light to scatter and leak out of the lens, leaving displays too dim to read outdoors.
Top left and center show white text projected over a real-world scene in bright sunlight, and top right shows a color image in a well-lit room. Bottom shows red, green and blue test visuals, fruit graphics, and grid and Siemens star patterns captured in the dark to assess contrast and resolution across different lighting conditions. Courtesy of Pohang University of Science and Technology
Conventional waveguides also distort color because red, green and blue wavelengths bend at different angles and travel at varying efficiencies through microscopic surface patterns.
Led by Rho Jun-suk, a professor of mechanical engineering at POSTECH, alongside researchers Yoon Jung-geun of Samsung Research and Kang Hyun-jung of POSTECH, the team redesigned the entire optical path inside the lens rather than optimizing isolated surface structures. By etching silicon nitride nanostructures smaller than the wavelength of light across 29 distinct zones, they steered stray light back toward the eye across multiple pathways.
To balance color, the researchers stacked two specialized layers — one tuned for blue and green light, the other for red and green — into a single 1.5-millimeter assembly. The prototype achieved a 30-degree diagonal field of view and an 8-by-8-millimeter "eyebox," allowing the image to remain stable even if the glasses slip slightly down the wearer’s nose. In field tests, the lenses displayed crisp white text outdoors and full-color graphics indoors at just 30 percent display power.
"This achievement demonstrates that by precisely controlling how light travels inside a lens, we can deliver bright, clear visuals outdoors even through thin eyewear," Rho said.
Significant hurdles remain before commercial rollout. The team noted that future iterations must minimize rainbow-like glare caused by ambient sunlight hitting the nanostructures, consolidate the dual layers into a single sheet and adapt nanoimprint manufacturing for mass production.
This article was published with the assistance of generative AI and edited by The Korea Times.