Polishing and testing of the 1.5 m SiC Ml mirror of the ALADIN instrument on the ADM-Aeolus satellite of ESA

摘要

The Aladin instrument on the ADM-Aeolus satellite of ESA has a parabolic M1 mirror of silicon carbide (SiC) with diameter of 1.5 m, fast focal ratio of f/0.9 and light-weighting to 25 kg/m~2. The lidar instrument is operated at the near ultraviolet wavelength of 355 nm, which requires high optical quality and good smoothness of the polishing finish. In this paper we present descriptions of the testing and polishing methods used during ALADIN Ml lapping and polishing to the specified wave front shape accuracy <150 nm rms and surface micro roughness < 5 nm rms.