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Proceedings Paper

Layer-oriented wavefront sensor for MAD: status and progress
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Paper Abstract

A demonstrator of the multi-conjugate adaptive optics concept is under construction at ESO and will be installed on the Nasmyth focus of the VLT. This demonstrator called MAD will have two different wavefront sensor channels: Shack-Hartmann and Layer-Oriented; in this article we only describe the Layer-Oriented one. The Layer-Oriented wavefront sensor can select eight reference stars in the two arc-minutes corrected field of view in order to have a maximum of two references in each quarter of the field. XY stages will remotely adjust the position of each reference star selector. The starlight will be fed onto two detectors and two completely independent loops will drive the deformable mirrors, one conjugated to the ground and the other to an altitude of approximately 8 km. The Layer-Oriented wavefront sensor will use the same CCDs than the Shack-Hartmann channel and the pupil will be divided into 9×9 subapertures both for the high and for the ground layer. The spatial sampling of the subapertures will be different for the two CCDs and their integration time will be tuned to typical values of the conjugated altitudes characteristic wind speed. The overall status of the instrument with respect to optics, mechanics, electronics and software is given hereafter. We also summarize the progress on the procurement phase and give the time schedule for the assembling, integration and testing phases.

Paper Details

Date Published: 7 February 2003
PDF: 10 pages
Proc. SPIE 4839, Adaptive Optical System Technologies II, (7 February 2003); doi: 10.1117/12.459036
Show Author Affiliations
Elise Vernet-Viard, Osservatorio Astrofisico di Arcetri (Italy)
Roberto Ragazzoni, Osservatorio Astrofisico di Arcetri/INAF and Max-Planck-Institut fur Astronomie (Italy)
Carmelo Arcidiacono, Univ. degli Studi di Firenze (Italy)
Andrea Baruffolo, Osservatorio Astronomico di Padova/INAF (Italy)
Emiliano Diolaiti, Univ. degli Studi di Padova (Italy)
Jacopo Farinato, Osservatorio Astrofisico di Arcetri (Italy)
Enrico Fedrigo, European Southern Observatory (Germany)
Enrico Marchetti, European Southern Observatory (Germany)
Renato Falomo, Osservatorio Astronomico di Padova (Italy)
Simone Esposito, Osservatorio Astrofisico di Arcetri (Italy)
Marcel Carbillet, Osservatorio Astrofisico di Arcetri (Italy)
Christophe Verinaud, Osservatorio Astrofisico di Arcetri (Italy)

Published in SPIE Proceedings Vol. 4839:
Adaptive Optical System Technologies II
Peter L. Wizinowich; Domenico Bonaccini, Editor(s)

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