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Proceedings Paper

Adaptive optics: effect of sampling rate and time lags on the closed loop bandwidth
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Paper Abstract

An adaptive optics system is considered as a multi loops servo system. The main components of the ioops are: - the wavefront sensor, - the real time digital processor, - the adaptive mirror and the high voltage control amplifiers. These loops are closed via the wavefront itself. Generally the detector of the wavefront sensor is a CCD camera. At first, images of the CCD matrix are digitized and the processor computes the local slopes of the wavefront ; secondly, the processor performs the calculation needed to output the values of the controls. Finally data are sended to the adaptive mirror through a digital/analog converter and the power amplifiers. A scheme of the loops is given where each major constituent is replaced by its transfer function. The time lags due to the CCD matrix and calculations are expressed. Using the Nichols criterion which defines the stability of the loops, the effects of the sampling rate and time lags on gain and bandwidth are studied. The results of a numerical model are given and comparisons are made with the COME-ON experiments. Same paper has been presented during the SPIE's 1990 Symposium on Astronomical Telescopes and Instrumentation for the 21St Century in February 1990.

Paper Details

Date Published: 1 August 1990
PDF: 18 pages
Proc. SPIE 1271, Adaptive Optics and Optical Structures, (1 August 1990); doi: 10.1117/12.20393
Show Author Affiliations
Jean-Paul Gaffard, Laserdot (France)
Corinne Boyer, Laserdot (France)

Published in SPIE Proceedings Vol. 1271:
Adaptive Optics and Optical Structures
Joachim J. Schulte-in-den-Baeumen; Robert K. Tyson, Editor(s)

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