We describe a prototype trace gas sensor designed for real-time detection of multiple chemicals. The sensor uses an external cavity quantum cascade laser (ECQCL) swept over its tuning range of 940-1075 cm^-1 (9.30-10.7 μm) at a 10 Hz repetition rate. The sensor was designed for operation in multiple modes, including gas sensing within a multi-pass Heriott cell and intracavity absorption sensing using the ECQCL compliance voltage. In addition, the ECQCL compliance voltage was used to reduce effects of long-term drifts in the ECQCL output power. The sensor was characterized for noise, drift, and detection of chemicals including ammonia, methanol, ethanol, isopropanol, Freon- 134a, Freon-152a, and diisopropyl methylphosphonate (DIMP). We also present use of the sensor for mobile detection of ammonia downwind of cattle facilities, in which concentrations were recorded at 1-s intervals.

Date Published: 8 February 2015
PDF: 14 pages
Proc. SPIE 9370, Quantum Sensing and Nanophotonic Devices XII, 93700Z (8 February 2015); doi: 10.1117/12.2080852

Published in SPIE Proceedings Vol. 9370:
Quantum Sensing and Nanophotonic Devices XII
Manijeh Razeghi; Eric Tournié; Gail J. Brown, Editor(s)