Simultaneous exhaled carbonyl sulfide (OCS) and carbon dioxide concentration measurements in human breath are demonstrated with a compact pulsed quantum-cascade laser-based gas sensor. We achieved a noise-equivalent sensitivity (1ς) of 1.2 parts per billion by measuring a well-isolated OCS <i>P</i>(11) absorption line in the ν<sub>3</sub> band at 2057.6 cm<sup>−1</sup> using an astigmatic Herriott cell of 36-m optical path length and 0.4-s acquisition time.
© 2004 Optical Society of America
Gerard Wysocki, Matt McCurdy, Stephen So, Damien Weidmann, Chad Roller, Robert F. Curl, and Frank K. Tittel, "Pulsed Quantum-Cascade Laser-Based Sensor for Trace-Gas Detection of Carbonyl Sulfide," Appl. Opt. 43, 6040-6046 (2004)