Key challenges for the production of ELT M1 segments at Safran Reosc

In 2017, the European Southern Observatory (ESO) awarded a contract for the manufacturing of the segments of the primary mirror for the Extremely Large Telescope (ELT) to Safran Reosc. Since then, we designed a production unit dedicated for ELT M1. From spherical mirror blanks, we first glue 39 pads per segment. We then shape, polish and cut the segments with 133 different off-axis aspheric definitions. We finish them to nanometer accuracy using ion beam figuring and a fully automated interferometric test bench. Now manufacturing has begun, we present the solutions and methods that we developed to manufacture more than one segment per day.