ELT: 4-meter mirror blank cast for the world’s largest telescope

The ELT team of SCHOTT Advanced Optics has started the production of the 4.25-meter secondary mirror substrate (M2) for the Extremely Large Telescope (ELT). M2 is the largest convex mirror ever made and employed on a telescope.

SCHOTT has been awarded the contract for the production of M2 in January 2017 by the European Southern Observatory (ESO).

Due to the very narrow specification for the quality of the glass, the casting had to meet extremely high demands. After the grinding, a defect-free, extremely curved mirror substrate only 10 centimeters thick is to be created from the blank that still weighs several tons.

Learn more about the ELT mirror design from an infographics which is located on a microsite that deals with this mega astronomy project. You can find the latest press information of the ESO here. Additionally, short video, called ESOcast, gives you exclusive insights to the cast process. You can watch it here.