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14 June 1995 Fibered recombination unit for the Infrared-Optical Telescope Array
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The Infrared Optical Telescope Array (IOTA) is an interferometric facility currently observing in the near infrared bands at the Smithsonian Institution's Fred Lawrence Whipple Observatory in Arizona. The 45 cm siderostats can be moved on an L-shaped track allowing discrete bases ranging between 5 and 38 m. The capability to combine beams with fiber optics in the K band (2 micrometers <EQ (lambda) <EQ 2.4 micrometers ) has been demonstrated on the Fiber Link Unit for Optical Recombination (FLUOR) at Kitt Peak National Observatory, in which two existing 0.8 m telescopes have been coherently coupled by means of optical fibers. FLUOR is now set as a focal instrument of IOTA. It uses single-mode fluoride glass waveguides and couplers as a substitute for mirrors and beamsplitters to perform beam transportation and recombination. Processing the light in single-mode waveguides offers the possibility to self-calibrate each interferogram against the loss of fringe visibility induced by atmospheric turbulence, thus improving the accuracy of the fringe visibility measurements. The FLUOR unit can be operated as a Mach-Zehnder interferometer to produce zero-baseline spectra used in double-Fourier interferometry to obtain the visibility as a function of wavelength. In the current status, a N-S baseline of 21.2 m is used to observe late-type starts and derive their angular diameters.
© (1995) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Guy S. Perrin, Vincent Coude du Foresto, Stephen T. Ridgway, Jean-Marie Mariotti, and James A. Benson "Fibered recombination unit for the Infrared-Optical Telescope Array", Proc. SPIE 2476, Fiber Optics in Astronomical Applications, (14 June 1995);

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