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Proceedings Paper

Current status of the IOTA interferometer
Author(s): Nathaniel P. Carleton; Wesley A. Traub; Marc G. Lacasse; Peter Nisenson; Michael R. Pearlman; Robert D. Reasenberg; Xinqi Xu; Charles M. Coldwell; Alexander Panasyuk; James A. Benson; Costas D. Papaliolios; Read Predmore; F. Peter Schloerb; H. Melvin Dyck; David M. Gibson
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Paper Abstract

The first two telescopes of the Infrared-Optical Telescope Array (IOTA) project are now in place and yielding data at the Smithsonian Institution's F. L. Whipple Observatory on Mt. Hopkins, near Tucson, Arizona. The IOTA collectors are 45 cm in diameter, and may be moved to various stations in an L-shaped configuration with a maximum baseline of 38 m. A third collector will be added as soon as funding permits. Each light-collector assembly consists of a siderostat feeding a stationary afocal Cassegrain telescope that produces a 10-X reduced parallel beam, which is in turn directed vertically downward by a piezo-driven active mirror that stabilizes the ultimate image position. The reduced beams enter an evacuated envelope and proceed to the corner of the array, where they are turned back along one arm for path compensation. The delay line, in one beam, consists of two parts: one dihedral reflector positioned in a slew-and-clamp mode to give the major part of the desired delay; and a second dihedral mounted on an air-bearing carriage to provide the variable delay that is needed. After delay, the beams exit from the vacuum and are directed by dichroic mirrors into the infrared beam-combination and detection system. The visible light passes on to another area, to the image-tracker detectors and the visible-light combination and detection system. The beams are combined in pupil-plane mode on beam splitters. The combined IR beams are conveyed to two cooled single-element InSb detectors. The combined visible-light beams are focussed by lenslet arrays onto multimode optical fibers that lead to the slit of a specially-designed prism spectrometer. For the visible mode, the delay line is run at several wavelengths on one side of the zero- path point, so that several cycles of interference occur across the spectrum. First results were obtained with the IR system, giving visibilities for several K and M stars, using 2.2 micrometers radiation on a N-S baseline of 21.2 m. From these measurements we obtained preliminary estimates of effective stellar diameters in the K band.

Paper Details

Date Published: 9 June 1994
PDF: 14 pages
Proc. SPIE 2200, Amplitude and Intensity Spatial Interferometry II, (9 June 1994); doi: 10.1117/12.177236
Show Author Affiliations
Nathaniel P. Carleton, Smithsonian Astrophysical Observatory (United States)
Wesley A. Traub, Smithsonian Astrophysical Observatory (United States)
Marc G. Lacasse, Smithsonian Astrophysical Observatory (United States)
Peter Nisenson, Smithsonian Astrophysical Observatory (United States)
Michael R. Pearlman, Smithsonian Astrophysical Observatory (United States)
Robert D. Reasenberg, Smithsonian Astrophysical Observatory (United States)
Xinqi Xu, Smithsonian Astrophysical Observatory (United States)
Charles M. Coldwell, Smithsonian Astrophysical Observatory (United States)
Alexander Panasyuk, Smithsonian Astrophysical Observatory (United States)
James A. Benson, Harvard Univ. (United States)
Costas D. Papaliolios, Harvard Univ. (United States)
Read Predmore, Univ. of Massachusetts/Amherst (United States)
F. Peter Schloerb, Univ. of Massachusetts/Amherst (United States)
H. Melvin Dyck, Univ. of Wyoming (United States)
David M. Gibson, MIT Lincoln Lab. (United States)

Published in SPIE Proceedings Vol. 2200:
Amplitude and Intensity Spatial Interferometry II
James B. Breckinridge, Editor(s)

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