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Proceedings Paper

Adaptive DFT-based fringe tracking and prediction at IOTA
Author(s): Edward Wilson; Ettore Pedretti; Jesse Bregman; Robert W. Mah; Wesley Arthur Traub
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Paper Abstract

An automatic fringe tracking system has been developed and implemented at the Infrared Optical Telescope Array (IOTA). In testing during May 2002, the system successfully minimized the optical path differences (OPDs) for all three baselines at IOTA. Based on sliding window discrete Fourier transform (DFT) calculations that were optimized for computational efficiency and robustness to atmospheric disturbances, the algorithm has also been tested extensively on off-line data. Implemented in ANSI C on the 266 MHz PowerPC processor running the VxWorks real-time operating system, the algorithm runs in approximately 2.0 milliseconds per scan (including all three interferograms), using the science camera and piezo scanners to measure and correct the OPDs. Preliminary analysis on an extension of this algorithm indicates a potential for predictive tracking, although at present, real-time implementation of this extension would require significantly more computational capacity.

Paper Details

Date Published: 20 October 2004
PDF: 12 pages
Proc. SPIE 5491, New Frontiers in Stellar Interferometry, (20 October 2004); doi: 10.1117/12.552979
Show Author Affiliations
Edward Wilson, Intellization (United States)
Ettore Pedretti, Harvard-Smithonian Ctr. for Astrophysics (United States)
Univ. of Michigan (United States)
Jesse Bregman, NASA Ames Research Ctr. (United States)
Robert W. Mah, NASA Ames Research Ctr. (United States)
Wesley Arthur Traub, Harvard-Smithsonian Ctr. for Astrophysics (United States)

Published in SPIE Proceedings Vol. 5491:
New Frontiers in Stellar Interferometry
Wesley A. Traub, Editor(s)

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