Nicholas Langellier

Green astro-comb for HARPS-N

We report the design, installation and testing of a broadband green astro-comb on the HARPS-N spectrograph at the TNG telescope. The astro-comb consists of over 7000 narrow lines (<10-6 nm width) spaced by 16 GHz (0.02 nm at 550 nm) with wavelengths stabilized to the Global Positioning System (GPS) and with flat power from 500 to 620 nm. The narrow lines are used to calibrate the spectrograph and measure its line profile. The short term sensitivity of HARPS-N is measured to be less than 2 cm/s and the long-term drift of the spectrograph is approximately 10 cm/s/day. The astrocomb has been partially automated with future work planned to turn the astro-comb into a fully automated, push button instrument.

A green astro-comb for Earth-like exoplanet searches

Our astro-comb, providing >7000 lines spaced by 16 GHz from 500-620 nm, has been deployed at TNG telescope as a wavelength calibrator for HARPS-N spectrograph. It provides sub-10 cm/s calibration accuracy required for exo-Earth searches.

Spectrally flat, broadband visible-wavelength astro-comb

We demonstrate a broadband visible-wavelength astro-comb enabled by two key technologies: dispersion-managed, fiber-optic Cherenkov radiation for green-to-red source-comb generation and complementary chirped-mirror pairs for constructing broadband Fabry-Perot filtering cavities.