South Korean researchers have developed a new image sensor that maintains accurate color separation at any angle of light incidence, using metamaterial technology that precisely controls light flow. The commercialization of this technology is expected to enable clearer photographs in low-light conditions even as smartphones become thinner.
On the 15th, a research team led by Professor Jang Min-seok from KAIST's School of Electrical Engineering announced they had developed metamaterial technology for image sensors that can stably separate colors regardless of light incidence angle, in collaboration with Professor Jung Hae-joon's team at Hanyang University.
Conventional smartphone cameras have captured images by concentrating light through very small lenses. However, as pixels inside cameras have become increasingly miniature, lenses alone can no longer gather sufficient light.
This led to the emergence of "nanophotonic color routers." Instead of collecting light with lenses, this metamaterial-based technology designs pathways invisible to the naked eye that precisely separate incoming light into red (R), green (G), and blue (B) colors.
Samsung Electronics previously demonstrated commercial viability by applying this technology to actual image sensors under the name "Nano Prism." Theoretically, stacking multiple layers of extremely fine nanostructures can collect more light and separate colors more accurately.
However, existing nanophotonic color routers had limitations for commercial smartphone camera applications. They only functioned well when light entered straight on, suffering from "oblique incidence problems" where colors mixed or performance dropped significantly when light entered at an angle.
The research team solved this problem by applying "inverse design" methodology, allowing computers to autonomously find optimal structures rather than having humans design them directly. This yielded a color router structure capable of stable color separation regardless of light incidence angle.
As a result, while existing structures nearly lost functionality when light tilted by approximately 12 degrees, the newly designed structure maintained about 78% optical efficiency within a ±12 degree range, demonstrating stable color separation performance. This achieves a level sufficient for actual smartphone usage environments.
