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DM design issues for E-ELT and associated instruments

Abstract 304

Submitted by Anne COSTILLE


A. Costille, J.-M. Conan, C. Petit, T. Fusco




Adaptive optics (AO) provides a real time correction of the turbulence and allows to improve the angular resolution of the astronomical telescopes. In AO the deformable mirror (DM) design is a key issue, and generally leads to complex trade-offs between performance and manufacturing constraints. The trade-offs and associated design rules used so far on 10m class telescopes have to be reconsidered now that we move from VLT to ELT instruments. The new design strategy also has to account for the important evolution of DM technologies.

This paper presents general DM design rules. The considered performance metric is the fitting error, that is evaluated for various turbulence conditions (seeing, outer scale relative to telescope diameter) and DM characteristics (pitch and geometry, influence functions and coupling factor...). In each case the stroke and interactuator stroke is evaluated. For instance we show that for large coupling factors a trade-off between fitting error and stroke amplitude can be performed. The design rules are illustrated with a combination of analytical results and numerical simulations.