GHIGO, MauroMauroGHIGOVECCHI, GabrieleGabrieleVECCHIBASSO, StefanoStefanoBASSOCitterio, ObertoObertoCitterioCIVITANI, Marta MariaMarta MariaCIVITANIPARESCHI, GiovanniGiovanniPARESCHISIRONI, GIORGIAGIORGIASIRONI2020-03-272020-03-2720150037-8720http://hdl.handle.net/20.500.12386/23640The INAF-Astronomical Observatory of Brera (INAF-OAB) is exploring the technical problems related to the ion beam figuring (IBF) of the Zerodur hexagonal mirrors (1.45 m corner to corner) of M1 for the European Extremely Large Telescope (E-ELT). As starting step a scaled down version mirror of the same material having size of 1 m corner to corner has been used to assess the relevant figuring problems. This specific mirror is spherical and has a radius of curvature of 3 m which allows a simple interferometric measurement setup. A mechanical support was designed to minimize its deformations due to gravity. The Ion Beam Figuring Facility used for this study has been recently completed in the Brera Observatory and has a figuring area of 170 cm x 140 cm. Aim of this study is the estimation and optimization of the time requested for the correction of the surface using also strategies to control the well-known thermal problems related to the Zerodur material. In this paper we report the results obtained figuring the 1 m corner-to-corner test segment.STAMPAenArticlehttp://sait.oat.ts.astro.it/MSAIt860315/index.html2015MmSAI..86..412GFIS/05 - ASTRONOMIA E ASTROFISICA