ELT M1 segment blanks queuing in the Safran Reosc polishing facilities

Primary mirror, M1, segments of ESO’s Extremely Large Telescope (ELT) awaiting polishing at Safran Reosc facilities in France. M1 segments begin their life as blanks made of Zerodur©, a glass-ceramic material. After the casting and machining of the blanks to their approximate shape, the segments are delivered to Safran Reosc in France, who are responsible for shaping them and mounting them on their support systems, as well as for polishing and testing.