Metalenses—flat surfaces that use nanostructures to focus light—promise to revolutionize optics by replacing the bulky, curved lenses currently used in optical devices with a simple, flat surface. But, these metalenses have remained limited in the spectrum of light they can focus well. Now a team of researchers at the Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS) has developed the first single lens that can focus the entire visible spectrum of light—including white light—in the same spot and in high resolution. This has only ever been achieved in conventional lenses by stacking multiple lenses.