New design for 'optical ruler' could revolutionize clocks, telescopes, telecommunications

Just as a meter stick with hundreds of tick marks can be used to measure distances with great precision, a device known as a laser frequency comb, with its hundreds of evenly spaced, sharply defined frequencies, can be used to measure the colors of light waves with great precision.

source https://www.sciencedaily.com/releases/2020/06/200622152507.htm