Share Email Print
cover

Proceedings Paper

Remote chemical sensing with quantum cascade lasers
Format Member Price Non-Member Price
PDF $17.00 $21.00

Paper Abstract

A trailer based sensor system has been developed for remote chemical sensing applications. The sensor uses quantum cascade lasers (QCL) that operate in the long wave infrared. The QCL is operated continuous wave, and its wavelength is both ramped over a molecular absorption feature and frequency modulated. Lock-in techniques are used to recover weak laser return signals. Field experiments have monitored ambient water vapor and small quantities of nitrous oxide, tetrafluoroethane (R134a), and hydrogen sulfide released as atmospheric plumes. Round trip path lengths up to 10 km were obtained using a retroreflector. Atmospheric turbulence was found to be the dominating noise source. It causes intensity fluctuations in the received power, which can significantly degrade the sensor performance. Unique properties associated with QCLs enabled single beam normalization techniques to be implemented thus reducing the impact that turbulence has on experimental signal to noise. Weighted data averaging was additionally used to increase the signal to noise of data traces. Absorbance sensitivities as low as ~1x10-4 could be achieved with 5 seconds of data averaging, even under high turbulence conditions.

Paper Details

Date Published: 15 September 2004
PDF: 9 pages
Proc. SPIE 5403, Sensors, and Command, Control, Communications, and Intelligence (C3I) Technologies for Homeland Security and Homeland Defense III, (15 September 2004); doi: 10.1117/12.541699
Show Author Affiliations
Warren W. Harper, Pacific Northwest National Lab. (United States)
Jana D Strasburg, Pacific Northwest National Lab. (United States)


Published in SPIE Proceedings Vol. 5403:
Sensors, and Command, Control, Communications, and Intelligence (C3I) Technologies for Homeland Security and Homeland Defense III
Edward M. Carapezza, Editor(s)

© SPIE. Terms of Use
Back to Top