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Proceedings Paper

The balloon experimental twin telescope for infrared interferometry (BETTII): optical design
Author(s): Todd J. Veach; Stephen A. Rinehart; John E. Mentzell; Robert F. Silverberg; Dale J. Fixsen; Maxime J. Rizzo; Arnab Dhabal; Caitlin E. Gibbons; Dominic J. Benford
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Paper Abstract

Here we present the optical and limited cryogenic design for The Balloon Experimental Twin Telescope for Infrared Interferometry (BETTII), an 8-meter far-infrared interferometer designed to fly on a high-altitude scientific balloon. The optical design is separated into warm and cold optics with the cold optics further separated into the far-infrared (FIR) (30-90 microns) and near-infrared (NIR) (1-3 microns). The warm optics are comprised of the twin siderostats, twin telescopes, K-mirror, and warm delay line. The cold optics are comprised of the cold delay line and the transfer optics to the FIR science detector array and the NIR steering array. The field of view of the interferometer is 2’, with a wavelength range of 30-90 microns, 0.5” spectral resolution at 40 microns, R~200 spectral resolution, and 1.5” pointing stability. We also present the design of the cryogenic system necessary for operation of the NIR and FIR detectors. The cryogenic system consists of a ‘Buffered He-7’ type cryogenic cooler providing a cold stage base temperature of < 280mK and 10 micro-Watts of heat lift and a custom in-house designed dewar that nominally provides sufficient hold time for the duration of the BETTII flight (24 hours).

Paper Details

Date Published: 24 July 2014
PDF: 12 pages
Proc. SPIE 9146, Optical and Infrared Interferometry IV, 91462H (24 July 2014); doi: 10.1117/12.2055659
Show Author Affiliations
Todd J. Veach, NASA Goddard Space Flight Ctr. (United States)
Stephen A. Rinehart, NASA Goddard Space Flight Ctr. (United States)
John E. Mentzell, NASA Goddard Space Flight Ctr. (United States)
Robert F. Silverberg, NASA Goddard Space Flight Ctr. (United States)
Dale J. Fixsen, Univ. of Maryland, College Park (United States)
Maxime J. Rizzo, Univ. of Maryland, College Park (United States)
Arnab Dhabal, Univ. of Maryland, College Park (United States)
Caitlin E. Gibbons, The Pennsylvania State Univ. (United States)
Dominic J. Benford, NASA Goddard Space Flight Ctr. (United States)

Published in SPIE Proceedings Vol. 9146:
Optical and Infrared Interferometry IV
Jayadev K. Rajagopal; Michelle J. Creech-Eakman; Fabien Malbet, Editor(s)

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