The last ELT M1 segment blanks leaving SCHOTT

The last batch of ZERODUR© blanks for the ELT’s primary mirror (M1) have been successfully cast by German company SCHOTT. Next stop: France, where company Safran Reosc will cut each segment blank to the right shape and polish it to a precision of 10 nanometres across the entire optical surface — meaning the surface irregularities of the mirror will be less than one thousandth of the width of a human hair.