Meeting highest performance requirements for lowest price and mass for the M1 segment support unit for E-ELT
conference paper
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. © 2010 SPIE.
Topics
ELTM1 support structureOpto-mechanicsStatic determinedELTForm errorsHexagonal segmentsLowest priceOpto-mechanicsPerformance parametersPerformance requirementsPrimary mirrorsSix-DOFStatic determinedStiffness-to-mass ratioStructure designSupport structuresThickness ratioAirborne telescopesGround supportsMechanicsOptical telescopesMirrors
TNO Identifier
425157
ISSN
0277786X
ISBN
9780819482235
Article nr.
No.: 77332H
Source title
Ground-Based and Airborne Telescopes III, 27 June - 2 July 2010, San Diego, CA, USA
Collation
9 p.