22 August 2014 Wavefront sensing in a partially illuminated, rotating pupil
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Abstract
LINC-NIRVANA is the near-infrared interferometric imaging camera for the Large Binocular Telescope. Once operational, it will provide an unprecedented combination of angular resolution, sensitivity, and field of view. Its pyramid-based layer-oriented MCAO systems are conjugated to the ground layer and to an additional layer in the upper atmosphere. The Groundlayer Wavefront Sensor optically coadds the light of up to 12 reference stars in the pupil, the Highlayer Wavefront Sensor optically combines the light of up to 8 reference stars in its metapupil. Each Wavefront Sensor has its own associated field derotator. It introduces a dependency of the sensor-actuator relation on the angle of the field derotator, which requires regular updates of the reconstructor in closed loop. In addition, the Highlayer Wavefront Sensor has to be able to reconstruct the incoming wavefronts by analyzing an only partially illuminated metapupil. The distribution of illuminated subapertures depends on the distribution of reference stars. For each pointing, a specific reconstruction matrix has to be generated, which only considers the illuminated subapertures. In this contribution we will present the concept of LINC-NIRVANA's wavefront reconstruction mechanism and report on laboratory and on-sky tests.
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Thomas Bertram, Thomas Bertram, Kalyan Kumar Radhakrishnan Santhakumari, Kalyan Kumar Radhakrishnan Santhakumari, Luca Marafatto, Luca Marafatto, Carmelo Arcidiacono, Carmelo Arcidiacono, Jürgen Berwein, Jürgen Berwein, Roberto Ragazzoni, Roberto Ragazzoni, Thomas M. Herbst, Thomas M. Herbst, "Wavefront sensing in a partially illuminated, rotating pupil", Proc. SPIE 9148, Adaptive Optics Systems IV, 91485M (22 August 2014); doi: 10.1117/12.2057384; https://doi.org/10.1117/12.2057384
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