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Proceedings Paper

Pathfinder first light: alignment, calibration, and commissioning of the LINC-NIRVANA ground-layer adaptive optics subsystem
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Paper Abstract

We present descriptions of the alignment and calibration tests of the Pathfinder, which achieved first light during our 2013 commissioning campaign at the LBT. The full LINC-NIRVANA instrument is a Fizeau interferometric imager with fringe tracking and 2-layer natural guide star multi-conjugate adaptive optics (MCAO) systems on each eye of the LBT. The MCAO correction for each side is achieved using a ground layer wavefront sensor that drives the LBT adaptive secondary mirror and a mid-high layer wavefront sensor that drives a Xinetics 349 actuator DM conjugated to an altitude of 7.1 km. When the LINC-NIRVANA MCAO system is commissioned, it will be one of only two such systems on an 8-meter telescope and the only such system in the northern hemisphere. In order to mitigate risk, we take a modular approach to commissioning by decoupling and testing the LINC-NIRVANA subsystems individually. The Pathfinder is the ground-layer wavefront sensor for the DX eye of the LBT. It uses 12 pyramid wavefront sensors to optically co-add light from natural guide stars in order to make four pupil images that sense ground layer turbulence. Pathfinder is now the first LINC-NIRVANA subsystem to be fully integrated with the telescope and commissioned on sky. Our 2013 commissioning campaign consisted of 7 runs at the LBT with the tasks of assembly, integration and communication with the LBT telescope control system, alignment to the telescope optical axis, off-sky closed loop AO calibration, and finally closed loop on-sky AO. We present the programmatics of this campaign, along with the novel designs of our alignment scheme and our off-sky calibration test, which lead to the Pathfinder’s first on-sky closed loop images.

Paper Details

Date Published: 7 August 2014
PDF: 12 pages
Proc. SPIE 9148, Adaptive Optics Systems IV, 914828 (7 August 2014); doi: 10.1117/12.2056737
Show Author Affiliations
Derek Kopon, Max-Planck-Institut für Astronomie (Germany)
Al Conrad, Max-Planck-Institut für Astronomie (Germany)
Carmelo Arcidiacono, INAF - Osservatorio Astrofisico di Bologna (Italy)
Tom Herbst, Max-Planck-Institut für Astronomie (Germany)
Valentina Viotto, INAF - Osservatorio Astronomico di Padova (Italy)
Jacopo Farinato, INAF - Osservatorio Astronomico di Padova (Italy)
Maria Bergomi, INAF - Osservatorio Astronomico di Padova (Italy)
Roberto Ragazzoni, INAF - Osservatorio Astronomico di Padova (Italy)
Luca Marafatto, INAF - Osservatorio Astronomico di Padova (Italy)
Harald Baumeister, Max-Planck-Institut für Astronomie (Germany)
Thomas Bertram, Max-Planck-Institut für Astronomie (Germany)
Jürgen Berwein, Max-Planck-Institut für Astronomie (Germany)
Florian Briegel, Max-Planck-Institut für Astronomie (Germany)
Ralph Hofferbert, Max-Planck-Institut für Astronomie (Germany)
Frank Kittmann, Max-Planck-Institut für Astronomie (Germany)
Martin Kürster, Max-Planck-Institut für Astronomie (Germany)
Lars Mohr, Max-Planck-Institut für Astronomie (Germany)
Kalyan Radhakrishnan, Max-Planck-Institut für Astronomie (Germany)

Published in SPIE Proceedings Vol. 9148:
Adaptive Optics Systems IV
Enrico Marchetti; Laird M. Close; Jean-Pierre Véran, Editor(s)

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