Carbon fibre composite deformable mirrors: Developments at UCL

Adaptive optics performance is essential for achieving the demanding science goals set for the ground-based optical telescopes of the future - the so-called extremely large telescopes (ELTs). Research into novel technologies for lightweight and robust active and adaptive mirrors is crucial for ensuring this capability. Surface quality, form, and a high level of stability during operation are very important criteria for such mirrors. In 2004 we reported initial results from a project into the design and manufacture of a prototype carbon fibre reinforced polymer (CFRP) deformable mirror. This system has now been extensively characterised and tested, and results of dynamical testing and influence function measurements are discussed here. Manual grinding and polishing resulted in a residual form error of the order of 10 μ m P-V and a surface roughness of approximately 5 nm rms. A good agreement was observed between the modeling data and experimental results.