Designing the primary mirror support for the E-ELT

Described is the M1 segment support, as designed by TNO in the period 2015- 2016. The design has significantly changed and improved compared to the earlier designs. During the period 2009-2010 prototypes for the primary mirror support of the E-ELT have been developed. These have been extensively tested by ESO. Design improvement were found to be necessary, especially in the field of manufacturability and maintainability. Furthermore, the technical performance had to improve in specific areas as well. This has evolved into a new specifications which have resulted in a new design for the segment support structure. The design rules that have led to the prototype design have been maintained but the implementation has been much improved. Also considerable improvement has been obtained with respect to the dynamic behavior. Accessibility and visibility on all parts and subsystems has changed such that everything is now clearly visible. Despite the increased performance no mass increase has been recorded meaning that more efficient use has been made of the material. The active means to influence the segment shape by use of the warping harness has been completely redesigned. A very important quality that has been achieved is simplicity. Hence a minimum amount of components is used. Reliability and safety are other aspects that have been greatly improved compared to the prototypes. The design for the M1 segment support provides an answer that not only performs to specification but one that can be operated in a telescope environment, all 798 of them