On 26 October 2016, the ESO Finance Committee approved several major contracts for optical components as part of the European Extremely Large Telescope (E-ELT) construction phase. This marks another key milestone towards first light in 2024 of the world's largest optical/near-infrared telescope.
The following contracts were approved:
- M1 polishing
- M1 edge sensors
- M2 blank
- M3 blank
- M3 polishing
- M2 and M3 cells
Certainly the most important is the contract for the polishing of the segments that form the 39-metre diameter primary mirror (M1) of the E-ELT. This is the second largest contract after the Dome and Main Structure (see Organisation Release). In order to control the position and phasing of the M1 segments, it is also necessary to have very accurate sensors positioned at the edges of each segment, to measure, in real-time, any misalignment of the mirrors which can then be corrected by the telescope control system.
The other contracts are for the purchase of the blanks and supporting mounting cells for the secondary (M2) and tertiary (M3) mirrors and polishing of M3. Both M2 and M3 are large (4-metre) diameter mirrors, that, in combination with M1 and the adaptive mirrors M4 and M5, will deliver the optical beam to the instruments. A video showing the optical path for the E-ELT can be found here.