Meeting highest performance requirements for lowest price and mass for the M1 segment support unit for E-ELT

Jan Nijenhuis; Roger Hamelinck; Ben Braam; M. Cayrel

doi:10.1117/12.857175

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5 August 2010 Meeting highest performance requirements for lowest price and mass for the M1 segment support unit for E-ELT

Jan Nijenhuis, Roger Hamelinck, Ben Braam, M. Cayrel

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Proceedings Volume 7733, Ground-based and Airborne Telescopes III; 77332H (2010) https://doi.org/10.1117/12.857175
Event: SPIE Astronomical Telescopes + Instrumentation, 2010, San Diego, California, United States

Abstract

The largest optical telescope in the world will be the E-ELT. Its primary mirror will be 42m in diameter. This mirror will consist of 984 hexagonal segments that are all individually supported. Each mirror will be controlled in six DOF while local shaping of the segments is provided by so called warping harnesses. These will correct for focus, astigmatism and trefoil. Hence a mirror with an extreme diameter to thickness ratio of almost 30 is obtained. Its support structure must guarantee a maximum surface form error of 30 nm rms independent of the segment attitude. Furthermore its stiffness to mass ratio must allow natural frequencies of 50Hz or higher to obtain sufficient bandwidth for the actuators that control the piston and tip/tilt of the segment. Designing such structure is a challenge that has been successfully completed. Three prototypes have been built and are about to be delivered to ESO. This paper discusses the main performance requirements and how they could be transferred into an elegant structure design. Furthermore an overview will be given on the main performance parameters in order to see whether the present design can be further optimized.

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Jan Nijenhuis, Roger Hamelinck, Ben Braam, and M. Cayrel "Meeting highest performance requirements for lowest price and mass for the M1 segment support unit for E-ELT", Proc. SPIE 7733, Ground-based and Airborne Telescopes III, 77332H (5 August 2010); https://doi.org/10.1117/12.857175

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