Achieving a few cm/sec calibration repeatability for high resolution spectrographs: the laser frequency comb on HARPS

The laser frequency comb, with its extreme precision, opens a new window for high precision spectroscopy for current facilities, as well as for the ELT's. We report on the latest performance of the laser frequency comb obtained in combination with the HARPS spectrograph, which allowed calibration with cm/sec repeatability. The laser frequency comb system developed is described. Details of its laboratory set-up, characterization and integration with HARPS are shown. The results of the recent test campaigns are presented, showing excellent performance in terms of repeatability as well as wavelength coverage. Preliminary on sky data and next activities to integrate such a system in HARPS are presented.