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Proceedings Paper

A quantitative study of the practical sensitivity limit of a terahertz absorption spectrometer
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Paper Abstract

In gas spectroscopy, chemicals can be identified by the set of frequencies at which their absorption lines occur. The concentration can be quantitatively estimated from the intensity of any of the absorption lines. The sensitivity of the spectrometer, i.e., the minimum detectable concentration, is ideally limited by the ratio of the source power to detector noise-equivalent power. In practice, the sensitivity is usually orders of magnitude worse due to systematic effects. In this work we built a simple gas terahertz transmission spectrometer to analyze how the source output power stability, the detector sensitivity, and atmospheric pressure affect its sensitivity. As a test gas we used methyl chloride in a mixture with air and modifid the widths of the absorption lines by changing partial pressure of air. This demonstration of a simple absorption spectrometer gives us insight into the approach to making a highly sensitive terahertz spectrometer.

Paper Details

Date Published: 15 April 2008
PDF: 10 pages
Proc. SPIE 6949, Terahertz for Military and Security Applications VI, 694908 (15 April 2008); doi: 10.1117/12.784620
Show Author Affiliations
Jon E. Bjarnason, National Institute of Standards and Technology (United States)
Charles Dietlein, National Institute of Standards and Technology (United States)
Univ. of Colorado at Boulder (United States)
Erich N. Grossman, National Institute of Standards and Technology (United States)

Published in SPIE Proceedings Vol. 6949:
Terahertz for Military and Security Applications VI
James O. Jensen; Hong-Liang Cui; Dwight L. Woolard; R. Jennifer Hwu, Editor(s)

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