Optical frequency combs were first built in an effort to make better atomic clocks and change the way we define the second. But from this initial idea sprouted multiple advances in other areas as well, from finding dark matter to detecting disease in breath. Read more about these measurement devices: https://www.nist.gov/blogs/taking-measure/making-measurements-fine-toothed-comb-0 | National Institute of Standards and Technology (NIST)