SCHOTT: 500th M1 primary mirror segment for Extremely Large Telescope

International technology group SCHOTT has produced its 500th ZERODUR® glass ceramic mirror blank as part of its contract to supply segments for the M1 primary mirror of the European Southern Observatory’s Extremely Large Telescope.

Currently under construction on Cerro Armazones in Chile’s Atacama Desert, the ELT will be the largest optical telescope in the world with a 39-meter primary mirror, and will see its first light in 2027.

SCHOTT signed a contract with ESO in 2017 to supply at total of 949 ZERODUR® mirror blanks for the ELT’s M1 primary mirror (including 798 mirror blanks, 133 spare and 18 prototype segments) and delivered its first prototypes in 2019. Series production for the ELT at SCHOTT’s Mainz, Germany headquarters began in 2020, and the final mirror blanks will be produced in early 2024.

In addition to the M1 mirror blanks, ZERODUR® will also feature on the ELT’s convex M2 mirror (4.2 meters), concave M3 mirror (3.8 meters), and adaptive M4 mirror (2.4 meters). After production by SCHOTT, the mirror blanks are shipped to French company SAFRAN Reosc for polishing.

Thomas Werner, Head of the ELT Project at SCHOTT, welcoming the production milestone, said, “We are very proud to help shape the future of astronomy by supporting the European Southern Observatory in their important work on the ELT.”