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13 September 2012 Design and performance of an R-θ fiber positioner for the BigBOSS instrument
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The BigBOSS instrument is a proposed multi-object spectrograph for the Mayall 4m telescope at Kitt Peak, which will measure the redshift of 20 million galaxies and map the expansion history of the universe over the past 8 billion years, surveying 10-20 times the volume of existing studies. For each 20 minute observation, 5000 optical fibers are individually positioned by a close-packed array of 5000 robotic positioner mechanisms. Key mechanical constraints on the positioners are: ø12mm hardware envelope, ø14mm overlapping patrol zones, open-loop targeting accuracy ≤ 40μm, and step resolution ≤ 5μm, among other requirements on envelope, power, stability, and speed. This paper describes the design and performance of a newly-developed fiber positioner with R-θ polar kinematics, in which a flexure-based linear R-axis is stacked on a rotational θ-axis. Benefits over the usual eccentric parallel axis θ-φ kinematic approach include faster repositioning, simplified anti-collision schemes, and inherent anti-backlash preload. Performance results are given for complete positioner assemblies as well as sub-component hardware characterization.
© (2012) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Joseph H. Silber, Christoph Schenk, Eric Anderssen, Chris Bebek, Frederic Becker, Robert Besuner, Mario Cepeda, Jerry Edelstein, Henry Heetderks, Patrick Jelinsky, Thomas Johnson, Armin Karcher, Paul Perry, Rodney Post, Michael Sholl, Kenneth Wilson, and Zengxaing Zhou "Design and performance of an R-θ fiber positioner for the BigBOSS instrument", Proc. SPIE 8450, Modern Technologies in Space- and Ground-based Telescopes and Instrumentation II, 845038 (13 September 2012);

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