We present results from our recent research into carbon-fibre composite (CFC) mirror fabrication for optical and infra-red applications. In particular this research is aimed towards the next generation of extremely large telescopes to offer an alternative to thin glass shell adaptive secondary mirrors. We address the issues involved with CFC mirror production, in particular the accuracy of the form replication process, a suitable surface for polishing to optical quality, no fibre print-through, environmental stability (shape change due to thermal and moisture variations), material uniformity and lifetime. We have performed experiments into the effectiveness of cold electroplating thick nickel coatings to totally encapsulate the CFC base substrate; the manufacturing procedure and properties of the Ni-CFC mirror are described here.
ABSTRACT. Adaptive optics (AO) combines technologies that enable the correction in real time of the wavefront distortion caused by the terrestrial atmospheric turbulence. An adaptive secondary mirror (ASM), unlike conventional adaptive optics systems, does not add any polarization, reÑective losses, and emissivity.Following successful implementation of tip/tilt secondary mirrors, most recent large telescope projects have considered the possibility of incorporating ASMs. This paper brieÑy reviews the development of ASMs and examines the issues which have arisen and also presents the predicted performance of an ASM system. It is concluded that adaptive secondary approach is an equally satisfactory or preferred solution to conventional AO systems.
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