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          Institute: MPI für Astronomie     Collection: Publikationen_mpia     Display Documents



ID: 710690.0, MPI für Astronomie / Publikationen_mpia
Pathfinder first light: alignment, calibration, and commissioning of the LINC-NIRVANA ground-layer adaptive optics subsystem
Authors:Kopon, D.; Conrad, A.; Arcidiacono, C.; Herbst, T.; Viotto, V.; Farinato, J.; Bergomi, M.; Ragazzoni, R.; Marafatto, L.; Baumeister, H.; Bertram, T.; Berwein, J.; Briegel, F.; Hofferbert, R.; Kittmann, F.; Kürster, M.; Mohr, L.; Radhakrishnan, K.
Place of Publication:Bellingham, Wash.
Publisher:SPIE
Date of Publication (YYYY-MM-DD):2014
Audience:Not Specified
Abstract / Description: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.
External Publication Status:published
Document Type:Other
Communicated by:N. N.
Affiliations:MPI für Astronomie
Identifiers:URL:http://adsabs.harvard.edu/abs/2014SPIE.9148E..28K
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