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Proceedings Paper

Laboratory characterization of an APD-based tip-tilt corrector
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Paper Abstract

The atmospheric image motion control loop for the 3.6m Telescopio Nazionale Galileo (TNG) has been tested and characterized in lab using a turbulence generator. The tip-tilt sensor is based on four Avalanche Photodiodes and the tilt corrector is a voice coil actuated flat mirror. The feedback network is implemented using a a DSP-based system. We have used the same focal ratios of the beam as it will be experienced by the system at the foci of the TNG telescope. The collected data are time-series useful to perform a Fourier analysis aimed to estimate the effectiveness of the correction. These data can be compared with: theoretical and measured tilt spectra obtained at the telescope site, in order to predict the degree of correction that can be achieved by such a system; measured data on single components, like the transfer function of the tip-tilt mirror, the latency of the DSP calculation and the characterization of the APDs tip-tilt sensor unit. The collected data are also suitable to perform further simulations in order to plan which will be the more effective correction at the telescope foci under several different conditions of reference brightness and seeing parameters.

Paper Details

Date Published: 17 October 1997
PDF: 6 pages
Proc. SPIE 3126, Adaptive Optics and Applications, (17 October 1997); doi: 10.1117/12.290159
Show Author Affiliations
Simone Esposito, Osservatorio Astrofisico di Arcetri (Italy)
Enrico Marchetti, CISAS/Univ. degli Studi di Padova (Italy)
Roberto Ragazzoni, Osservatorio Astronomico di Padova (Italy)
Andrea Baruffolo, Osservatorio Astronomico di Padova (Italy)
Jacopo Farinato, Univ. degli Studi di Padova (Italy)
Luca Fini, Osservatorio Astrofisico di Arcetri (Italy)
Adriano Ghedina, Univ. degli Studi di Padova (Italy)
Piero Ranfagni, Osservatorio Astrofisico di Arcetri (Italy)
Armando Riccardi, Osservatorio Astrofisico di Arcetri (Italy)


Published in SPIE Proceedings Vol. 3126:
Adaptive Optics and Applications
Robert K. Tyson; Robert Q. Fugate, Editor(s)

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