The casting of the secondary mirror blank for ESO's Extremely Large Telescope (ELT) has been completed by SCHOTT at Mainz, Germany. The completed mirror will be 4.2 metres in diameter and weigh 3.5 tonnes. It will be the largest secondary mirror ever employed on an optical telescope and also the largest convex mirror ever produced.
ESO's 39-metre Extremely Large Telescope (ELT) will be the largest telescope of its kind ever built when it achieves first light in 2024. A new milestone has now been reached with the casting of the telescope's secondary mirror (M2), which is larger than the primary mirror of many of today's research telescopes.
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