SNU College of Engineering (Dean Char Kookheon) announces that the joint research led by Professor Lee Byoungho of the Department of Electrical and Computer Engineering has developed a lightweight and flat metalens that provides a wide field of view (FOV) to augmented reality (AR) glasses.
 
The AR superimposes a computer-generated image onto real-world scenes. Currently, a variety of AR glasses including Google’s Google Glass and Microsoft’s HoloLens is being launched to the market. However, these glasses all share a limitation that they have a narrow FOV. If large optical lenses are used to support a wider span, the weight and size must also increase and AR glass devices lose their practicality.
 
Hence, the joint research team under SNU Professor Lee Byoungho, Korea University (KU) Professor Kim Hwi, and Doctor Jeong Jun-Ho of the Korea Institute of Machinery & Materials (KIMM) creates a new metasurface eyepiece with a thickness of only 100 nanometers (nm). The metasurface is an artificial two-dimensional nanostructured interface with sub-wavelength thickness. It is receiving attention for its unique optical properties.
 
Specifically, the team has developed a key component to the metasurface: the see-through metalens that provides a transparent view of the real-world scenes, but serves as a wide-angle lens with a numerical aperture of 0.61 to AR images. The lens with only 100nm thickness is thin and light presenting applicability to head-mounted display devices.
 
The silicon nanostructure has been employed to the metalens. This has allowed Lee’s team to largely expand the diameter of their metalens to a much practical size of 2cm compared to the 1mm-sized conventional metalenses. Lee’s team has also suggested the feasibility of mass production with their experimental demonstrations of nanoimprinting processes.
 
The application of this see-through metalens to AR glasses significantly increases the viewing angle. Unlike conventional lenses, the see-through metalens can be placed in front of the user’s eyes, which maximizes the efficiency of the lens.
 
According to the research findings, the proposed system with the see-through lens has an ultra-wide FOV of more than 100 degrees and the experimental test of the prototype has demonstrated a maximum of 90 degrees FOV due to a limited lens aperture. Considering that most of the AR glasses only have a FOV of 25 degrees, this is a 10 times greater achievement that is anticipated to provide users a much intense and captivating sight.
 
Professor Lee explains, “We are the first in the world to provide a solution to the limited FOV of AR displays through the development of a metasurface eyepiece. This new technology shows great potential for application in next generation display technologies including virtual reality, augmented reality, and three-dimensional imaging.”
 
This research has received support from the Basic Research Program and the Global Frontier Program of the National Research Foundation of Korea (NRF) backed up by the Ministry of Science and ICT. Its findings have been published on the Nature Communications on November 1^st.


Nature Communications: https://www.nature.com/articles/s41467-018-07011-5