10 July 2008 Optical phasing of a segmented mirror with sub-nanometer precision: experimental results of the APE Internal Metrology
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Abstract
This paper presents a non-contact optical metrology measuring the pistons and tip/tilt angles of the 61 hexagonal segments of a compact-sized segmented mirror. The instrument has been developed within the scope of a design study for a European Extremely Large Telescope (E-ELT). It is used as reference sensor for cophasing of the mirror segments in closed loop control. The mirror shape is also measured by different types of stellar light-based phasing cameras whose performances will be evaluated with regard to a future E-ELT. Following a description of the system architecture, the second part of the paper presents experimental results demonstrating the level of precision: 0.48nm RMS in piston and 0.074 μrad RMS in tip and tilt.
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Rainer Wilhelm, Rainer Wilhelm, Bruno Luong, Bruno Luong, Alain Courteville, Alain Courteville, Sébastien Estival, Sébastien Estival, Frédéric Gonté, Frédéric Gonté, } "Optical phasing of a segmented mirror with sub-nanometer precision: experimental results of the APE Internal Metrology", Proc. SPIE 7012, Ground-based and Airborne Telescopes II, 701212 (10 July 2008); doi: 10.1117/12.787377; https://doi.org/10.1117/12.787377
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