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Updated: Dec 20, 2025

Measuring Dissolved Methane in Aquatic Ecosystems Using An Optical Spectroscopy Gas Analyzer
Published on: July 26, 2024
A dual-gas sensor for simultaneous detection of methane and acetylene based on time-sharing scanning assisted
Lewen Zhang1, Zhirong Zhang2, Pengshuai Sun3
1Anhui Provincial Key Laboratory of Photonic Devices and Materials, Anhui Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Hefei, Anhui 230031, China; University of Science and Technology of China, Hefei 230026, China.
Abstract:
Methane (CH4) and acetylene (C2H2) are important bioscience and chemical gases. The real-time monitoring and analysis of them have important research value in industrial process control. The time-sharing scanning assisted wavelength modulation spectroscopy (WMS) technique is developed for real-time and simultaneous detection of CH4 and C2H2. This system involves two near-infrared distributed feedback (DFB) lasers and a compact multipass cavity with an effective optical path of 52.2 m. The selected strong absorption lines of methane and acetylene are located at 6046.96 cm-1 and 6531.7 cm-1, respectively. The experiment environment is conducted at room temperature 23 °C and pressure 760 Torr. The sensor performance, including the minimum detection limit (MDL) and the stability, was improved by eliminating the influence of light intensity fluctuation using the WMS-2f/SAW technique. Allan deviation analysis indicates that a MDL of 0.1 ppm for CH4 and 0.2 ppm for C2H2 are achieved with 1-s integration time. And the instrument response time is about 44 s through the continuous analysis of standard gases. This sensitive, simple, reliable, and lowcost dual-gas sensor is very suitable for applications in the field environment, chemical process, and many other gas-phase analysis areas.
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