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Proceedings Paper

The L band high-speed guide camera with nanomesh resonant dichroic
Author(s): Thomas K. Greathouse; John H. Lacy; Paul M. Harvey; Daniel T. Jaffe; Adrian H. Lu; Mark D. Morgan
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Paper Abstract

TEXES, the Texas Echelon Cross Echelle Spectrograph, is an ideal instrument to study molecular clouds at a spectral resolving power of 100,000 between 5 and 25 μm. In many molecular clouds, high extinction often means that no visible stars are available for off-axis guiding. At a resolving power of 100,000, only the very brightest sources can be observed while guiding on the power in the dispersed IR spectra. We present the design of a high-speed on-axis guider for TEXES operating at 3.65 μm, a wavelength outside the spectrometer operating band where many of the target sources are still detectable for imaging. We use a new technology gold nanomesh resonant IR filter/mirror from EDTEK, that transmits 3.65 μm light to the guide detector with a peak transmittance of 60% while reflecting light from 5 μm long-ward with 98% efficiency to the dispersing elements in the spectrograph. A PC controls clocking patterns for the CRC-463 detector from Raytheon Infrared Operations and the analog to digital conversion of signals with a 14 bit A/D card. Image centroiding is done in software and then offsets are sent to the telescope for pointing adjustments or tip-tilt corrections when a tip-tilt secondary is available. This system is a prototype designed to test the feasibility of a similar guider for EXES, the Echelon Cross Echelle Spectrograph, mounted on SOFIA, the Stratospheric Observatory for Infrared Astronomy.

Paper Details

Date Published: 7 March 2003
PDF: 9 pages
Proc. SPIE 4841, Instrument Design and Performance for Optical/Infrared Ground-based Telescopes, (7 March 2003); doi: 10.1117/12.459963
Show Author Affiliations
Thomas K. Greathouse, Univ. of Texas at Austin (United States)
John H. Lacy, Univ. of Texas at Austin (United States)
Paul M. Harvey, Univ. of Texas at Austin (United States)
Daniel T. Jaffe, Univ. of Texas at Austin (United States)
Adrian H. Lu, Univ. of Texas at Austin (United States)
Mark D. Morgan, EDTEK (United States)

Published in SPIE Proceedings Vol. 4841:
Instrument Design and Performance for Optical/Infrared Ground-based Telescopes
Masanori Iye; Alan F. M. Moorwood, Editor(s)

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