High performance large lightweight mirrors fabrication adapted to stress-mirror polishing (SMP) technique

Earth observation space instruments require very tight optical performances in the most stringent configuration (observation in the optical wavelengths range). The optical quality of mirrors, mainly in term of both shape and roughness polishing quality, has to reach very tight specifications down to a few nanometers. In this paper, we present a new manufacturing process, based on Stress-Mirror Polishing (SMP) technique, dedicated to lightweight mirrors aspherisation. We consider specific features or constraints due to the structure of the honeycomb, while reducing footprint effects and inhomogeneous surface effects. We also identify the most efficient way to correct and/or anticipate these issues taking into account industrial constraints on real-scale mirrors. In this new process, both SMP technique and lightweight design have to be optimized.