24 September 2012 A fibre positioner solution for the 4MOST instrument
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Abstract
4MOST1 is a multi object spectrograph facility for ESO’s NTT or VISTA telescope. 4MOST is one of the two projects selected for a conceptual design study by ESO. The 4MOST instrument will be able to position < 1500 fibres in the focal plane and collect spectra in a high resolution (R=20000)2 and a low resolution (R=5000) mode (HRM, LRM). The spectral coverage for the LRM is 400-900 nm, the HRM covers 390-459 nm and 564-676 nm. We will present one of the possible positioner designs and first tests of some components for the focal plane array. The design follows the LAMOST3 positioner and has two rotational axes to move the fibre inside the patrol disc. Each axis consists of a stepper motor attached to micro harmonic drive (MHD). The small outer dimensions and high gear ratios of the MHD-stepper motor package, makes them perfectly suitable for our application. The MHD is also backlash free and self-locking what gives us the opportunity to minimize power consumption and heat dissipation during observation without loosing the position of the fibre on sky. The control electronics will also be miniaturized and part of the positioner unit.
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Florian Lang-Bardl, Ralf Bender, Frank Grupp, Marco Häuser, Hans-Joachim Hess, Veronika Junk, Ralf Kosyra, Bernard Muschielok, Josef Richter, Jörg Schlichter, Christoph Schwab, "A fibre positioner solution for the 4MOST instrument", Proc. SPIE 8446, Ground-based and Airborne Instrumentation for Astronomy IV, 844661 (24 September 2012); doi: 10.1117/12.925969; https://doi.org/10.1117/12.925969
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