Air holes turn silicon wafers into flat ultraviolet focusing mirrors for compact optics

The Quick Take

Traditional lenses and mirrors focus light using curved surfaces. Metasurfaces can achieve similar functions with a flat layer of nanoscale structures that locally control the phase of light. Extending these flat optics into the ultraviolet could support compact systems for high-resolution imaging, spectroscopy, and sensing, but it introduces a fundamental materials problem: many of the materials