7 March 2003 Cryogenic Fabry-Perot spectrometer for the near infrared
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Abstract
We have designed and built a high spectral resolution cryogenic double Fabry-Perot infrared spectrometer to survey the diffuse emission of ionized hydrogen (Br γ line) in the Galactic plane. In the initial survey, presented here, we employed the non-imaging mode of the spectrometer to achieve the best possible sensitivity for the faint diffuse emission. The emission measure detection limit was about 300 cm-6pc. The resolving power of the instrument is 104 and the simultaneous velocity range is approximately 200 km s-1. The spectrometer consists of a liquid nitrogen cryostat, which accommodates Fabry-Perot interferometers and a liquid helium cryostat for the InSb 256 x 256 detector. Each Fabry-Perot interferometer is located in a separate chamber in the cryostat. Tuning of the spectrometer is accomplished by varying the pressure of dry nitrogen gas in the chamber. The cold shields of the spectrometer and the detector cryostat are connected. Stray radiation is reduced by use of a cold stop, with the appropriate relay optics, located between the cryostats. This design limits stray background radiation and thermal radiation from the spectrometer itself, greatly improving the detection limit of the system. All of these design features maximize experiment sensitivity, which is limited by thermal emission from outside of the spectrometer, and by variation of the atmospheric emission lines.
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Alexander S. Kutyrev, Charles Leonard Bennett, Samuel Harvey Moseley, Ronald J. Reynolds, Fred L. Roesler, "Cryogenic Fabry-Perot spectrometer for the near infrared", Proc. SPIE 4841, Instrument Design and Performance for Optical/Infrared Ground-based Telescopes, (7 March 2003); doi: 10.1117/12.461750; https://doi.org/10.1117/12.461750
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KEYWORDS
Bromine

Spectroscopy

Fabry–Perot interferometers

Sensors

Calibration

Cryogenics

Infrared spectroscopy

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