Abstract

We describe a portable diode-laser-based sensor for NH₃ detection using vibrational overtone absorption spectroscopy at 1.53 µm. Use of fiber-coupled optical elements makes such a trace gas sensor rugged and easy to align. On-line data acquisition and processing requiring <30 s can be performed with a laptop PC running LabVIEW software. The gas sensor was used primarily for NH₃ concentration measurements with a sensitivity of 0.7 parts per million (signal-to-noise ratio of 3) over a two-week period in a bioreactor being developed at the NASA Johnson Space Center for water treatment technologies to support long-duration space missions. The feasibility of simultaneous, real-time measurements of NH₃ and CO₂ concentrations is also reported.

© 2001 Optical Society of America

Measurements of NH₃ and CO₂ with distributed-feedback diode lasers near 2.0 µm in bioreactor vent gases

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