Optical tests of the LUTIN Fabry-Pérot prototype

The soLar group University of Tor vergata fabry-perot INterferometer (LUTIN) is a narrow band filter based on an optical cavity resonator with Capacitance-Stabilised Etalon (CSE) control. The prototype, developed at the University of Rome Tor Vergata, is part of the study for the narrow band channel of the ADvanced Astronomy for HELIophysics (ADAHELI) mission designed to investigate the dynamics of solar atmosphere as part of the Italian Space Agency (ASI) Small Missions program. We developed the electro-mechanical control for the optical cavity, necessary for the tuning and the gap control of the instrument. We present the measures of the microroughness of the optical plates, performed with a Zygo interferometer, and the instrument spectral stability behaviour in on-optical-bench open-air mode. The measures refer to the upgraded version of the LUTIN prototype, which mounts the new λ/60 optical plates.