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Proceedings Paper

Sensitive absorption measurements in the near-infrared region using off-axis integrated cavity output spectroscopy
Author(s): Douglas S. Baer; Joshua B. Paul; Manish Gupta; Anthony O'Keefe
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Paper Abstract

A novel instrument that employs a high-finesse optical cavity as an absorption cell has been developed for sensitive measurements of gas mixing ratios using near-infrared diode lasers and absorption spectroscopy techniques. The instrument employs an off-axis trajectory of the laser beam through the cell to yield an effective optical path length of several kilometers without significant unwanted effects due to cavity resonances. As a result, a minimum detectable absorption of ~1.4x10-5 over an effective optical path of 4,200 meters was obtained in a 1.1-Hz detection bandwidth to yield a detection sensitivity of ~3.1x10-11 cm-1 Hz-1/2. The instrument has been applied for measurements of CO, CH4, C2H2, and NH3 in the 1530-1650 nm range, and stable isotopes of CO2 (13CO2, 12CO2, 12C16O18O) near 2052 nm.

Paper Details

Date Published: 23 September 2002
PDF: 10 pages
Proc. SPIE 4817, Diode Lasers and Applications in Atmospheric Sensing, (23 September 2002); doi: 10.1117/12.451461
Show Author Affiliations
Douglas S. Baer, Los Gatos Research (United States)
Joshua B. Paul, Los Gatos Research (United States)
Manish Gupta, Los Gatos Research (United States)
Anthony O'Keefe, Los Gatos Research (United States)

Published in SPIE Proceedings Vol. 4817:
Diode Lasers and Applications in Atmospheric Sensing
Alan Fried, Editor(s)

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