Successful start

Video impressions on the ZERODUR® M1
cast for the Extremely Large Telescope

The first segments for the main mirror of the Extremely Large Telescope (ELT) of the European Southern Observatory (ESO) have been successfully casted by SCHOTT at its facility in Mainz. These segments will form parts of the 39-metre main mirror, which will have 798 hexagonal segments – each measuring 1.4 metres across and about 5 centimetres thick – in total when completed. The ZERODUR® segments will work together as a single huge mirror to collect tens of millions of times as much light as the human eye. The ELT will be the largest optical eye in the sky when it sees first light in 2024. Marc Cayrel, head of ELT optomechanics at ESO, was present at the first castings: “It was wonderful to see the first segments being successfully cast. This cast at SCHOTT is a major milestone for the ELT!” The first segment castings are important as they allow the engineers at SCHOTT to validate and optimize the manufacturing process and the associated tools and procedures.

See our video from the impressive casts here:

January 10th, 2017

Oliver Hart
Advanced Optics