The measurement of the Interaction Matrices for the LINC-NIRVANA MCAO

Tom Herbst, Martin Kuerster, Roberto Ragazzoni, Harald Baumeister, Carmelo Arcidiacono, Jacopo Jacopo, Frank Kittman, Juergen Berwein, Florian Briegel, Kalyan Kumar Radhakrishnan Santhakumari, Valentina Viotto, Maria Bergomi (+3 others)
2017 Proceedings of the Adaptive Optics for Extremely Large Telescopes 5   unpublished
The commissioning of LINC-NIRVANA (LN) is ongoing at the Large Binocular Telescope (LBT). LN provides Multi-Conjugate Adaptive Optics (MCAO) correction for each side of the telescope using the Layer Oriented technique and using Natural Guide Stars (NGS). For each arm, two wavefront sensors (WFS), one conjugated to the ground and the other to 7km, co-add the light of all the reference stars within their respective fields of view, following the Multiple Field-of-View scheme. The two WFS
more » ... control two deformable mirrors (DMs), the 672-actuator adaptive secondary of the LBT (ground layer) and a 349-actuator DM from Xinetics (7km layer). The DMs projections on the WFS cameras rotate, since the opto-mechanics of LN are pupil fixed, while the NGS rotate. We need to provide a distinct control matrix for approximately each degree of rotation. We succeed in obtaining valid control matrices through numerical interpolation of a few calibrated interaction matrices. In this paper, we present the daytime calibration strategy and procedures for LINC-NIRVANA's DM-WFS interaction matrices.
doi:10.26698/ao4elt5.0067 fatcat:ca5bci2svrhjfjetfkr7hdxzcy