frequency comb

Chip-based devices known as frequency combs, which measure the frequency of light waves with unparalleled precision, have revolutionized time keeping, the detection of planets outside of our solar system and high-speed optical communication.
Now, scientists at the National Institute of Standards and Technology (NIST) and their collaborators have developed a new way of creating the combs that promises to boost their already exquisite accuracy and allow them to measure light over a range of frequencies that was previously inaccessible. The extended range will enable frequency combs to probe cells and other biological material.
The new devices, which are fabricated on a small glass chip, operate in a fundamentally different way from previous chip-based frequency combs, also known as microcombs.

On the cover of the Pink Floyd album Dark Side of the Moon, a prism splits a ray of light into all the colors of the rainbow. This multicolored medley, which owes its emergence to the fact that light travels as a wave, is almost always hiding in plain sight; a prism simply reveals that it was there.