First Shell of ELT Deformable Mirror Completed

The French optics company Safran Reosc has completed the first of six shells that will comprise the M4 deformable mirror system, which forms a fundamental part of ESO’s Extremely Large Telescope (ELT). When complete, the adaptive M4 mirror will be 2.4 metres in diameter and only 1.95 millimetres thick. This very thin mirror is one of the five main mirrors of the ELT’s optical system, with the main segmented mirror being 39 metres in diameter.