All-SiC telescope technology: recent progress and achievements

摘要

Last decade EADS-ASTRIUM and its partner Boostec,rnhas become world leader in the field of Silicon Carbidern(SiC) optical payloads. In the framework of earth andrnscientific observation, high and very high-resolutionrnoptical payloads have been developed. This leadershiprnallowed EADS-ASTRIUM to propose a large andrncomplete range of space-based system for opticalrnobservation. Ceramic mirrors and structures arernbecoming attractive for high precision light weightedrnopto-mechanical applications. Developments over thernpast 15 years by EADS-ASTRIUM and by Boostecrnhave demonstrated the feasibility and versatility of thernSiC material for numerous applications. The mostrnfavorable characteristics of this material are highrnstiffness, high thermal conductivity and low thermalrnexpansion (CTE). Furthermore, SiC allows relativelyrnquick and cheap manufacturing of components becausernthe components can be shaped with conventional toolsrnin a milling process of the green body material.rnThrough different joining processes, SiC allows forrnlarge size applications and systems. Only the scale ofrnthe available production facilities, the largest of whichrncurrently is 4 m in diameter, limits size of thernstructures and mirrors that can be manufactured.rnAfter a short recall of the SiC material properties, thisrnpaper describes recent impressive developmentsrnnamely the ∅ 3,5m primary mirror for Herschelrntelescope, the ∅ 1,5m primary mirror for Aladinrntelescope and the 1,5m x 0,6 m mirror demonstrator forrnthe GAIA mission. Main conclusion from the feasibilityrnstudy of the∅ 3,5m SPICA telescope are alsornpresented.