17 October 1997 Laboratory characterization of an APD-based tip-tilt corrector
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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.
© (1997) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Simone Esposito, Enrico Marchetti, Roberto Ragazzoni, Andrea Baruffolo, Jacopo Farinato, Luca Fini, Adriano Ghedina, Piero Ranfagni, and Armando Riccardi "Laboratory characterization of an APD-based tip-tilt corrector", Proc. SPIE 3126, Adaptive Optics and Applications, (17 October 1997); doi: 10.1117/12.290159; https://doi.org/10.1117/12.290159


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