Frequency combs for Astronomical Applications

"Laser frequency combs (LFCs) have found their way from laboratory spectroscopy into astronomy to serve as calibrators for spectrographs. We introduce the basic concepts of frequency combs and how they are used for astronomy. We present the results from test campaigns on HARPS, especially our last campaign in April 2015, when we permanently installed the LFC for HARPS and brought another LFC there for testing. Some lessons are learned from HARPS results for ESPRESSO. The ESPRESSO LFC in under building in Menlo and the laboratory characterization is showed."