Single metalens focuses all colors of the rainbow in one point

(Harvard John A. Paulson School of Engineering and Applied Sciences) 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 Harvard researchers has developed the first single lens that can focus the entire visible spectrum of light -- including whi...