Researchers at the University of California San Diego have demonstrated a novel optical metasurface capable of capturing images of the Sun’s magnetic field through a single snapshot without relying on moving parts. The achievement, reported in Science Advances, marks an important step toward integrating metasurface technology into advanced scientific instruments and future space missions, tells IEEE Spectrum.
Metasurfaces are engineered arrays of nanoscale structures designed to manipulate light at dimensions smaller than its wavelength. Unlike conventional diffraction gratings that primarily separate light by color and direction, metasurfaces can also distinguish different polarization states. This capability enables them to perform complex optical functions within a compact, lightweight component.
The research team integrated its metasurface device with the Dunn Solar Telescope in New Mexico to study polarized sunlight. Although sunlight is initially unpolarized, magnetic fields on and around the Sun alter its polarization characteristics. By measuring these changes, scientists can determine the strength and orientation of solar magnetic fields, which are essential for understanding space weather and coronal mass ejections that can affect Earth.
Traditional instruments perform these measurements using rotating optical components that capture multiple images and then reconstruct the polarization data. The new metasurface eliminates the need for moving parts by simultaneously recording all polarization information. This approach improves reliability and is particularly attractive for space-based telescopes, where mechanical systems increase complexity and create potential failure points.
The device consists of repeating patterns of tiny rectangular nanopillars fabricated on a glass substrate. Each pattern contains 144 pillars packed into an area less than 5 mm wide. Acting as a highly sophisticated beamsplitter, the metasurface separates incoming polarized light into multiple channels, enabling complete polarization measurements in a single exposure.
After passing vibration and thermal tests conducted with industry partner BAE Space & Mission Systems, the instrument successfully captured solar magnetic field images that closely matched observations from orbiting spacecraft. Beyond solar astronomy, the technology could benefit facial recognition systems, quantum optics experiments, and planet-hunting coronagraphs.
With NASA planning a solar-monitoring mission in the 2030s, the metasurface approach may become a strong candidate for next-generation space instrumentation, offering greater simplicity, reliability, and performance in a compact package.