E-ELT M4 Unit updated design and prototype results

We present the current design of the E-ELT M4 deformable mirror consolidated at the conclusion of the Preliminary Design activity. The most prominent features of this system are the SiC Reference Body now mounted to the positioner by a whiffle-tree and cell structure, actuators bricks, capacitive sensors layout and new cooling concept. All this allowed achieving the challenging stability requirements demanded to the M4U, as proved by analysis and test results measured on the Demonstration Prototype, which has been updated to implement the current design. The final design and construction contract is now on-going: Final Design Review is planned on mid 2017 and delivery to site by late 2022