• Acta Photonica Sinica
  • Vol. 49, Issue 10, 1012002 (2020)
Tao PANG1、2, Peng-shuai SUN1, Zhi-rong ZHANG1、2、3、*, Bian WU1, Hua XIA1、2, and Chi-min SHU4
Author Affiliations
  • 1Anhui Provincial Key Laboratory of Photonic Devices and Materials,Anhui Institute of Optics and Fine Mechanics,Chinese Academy of Sciences,Hefei 230031,China
  • 2Key Lab of Environmental Optics & Technology,Anhui Institute of Optics and Fine Mechanics,Chinese Academy of Sciences,Hefei 230031,China
  • 3Advanced Laser Technology Laboratory of Anhui Province,Heifei 230037,China
  • 4Department of Safety Health and Environmental Engineering,Yunlin University of Science and Technology,Yunlin,Taiwan 64002,China
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    DOI: 10.3788/gzxb20204910.1012002 Cite this Article
    Tao PANG, Peng-shuai SUN, Zhi-rong ZHANG, Bian WU, Hua XIA, Chi-min SHU. Design of Compact Full-range Laser Methane Sensor with Wide Temperature Range[J]. Acta Photonica Sinica, 2020, 49(10): 1012002 Copy Citation Text show less

    Abstract

    Account for big temperature difference and large dynamic range in the application environment, a compact full-range laser methane probe with a wide temperature range of -40~60℃ is designed. To reduce the volume of probe, cascade structure design is adopted for circuit. Single-chip microcomputer STM32F405 is used to realize laser temperature control, wavelength scanning modulation, digital phase-locked amplification and real-time inversion of concentration information. The circuit system and gas chamber are encapsulated in a stainless steel case of only Φ35 mm×60 mm, with windows in the middle to achieve physical isolation, ensuring intrinsic safety. At low concentration, wavelength modulation technology is used to ensure the measurement accuracy and measurement limit. Direct absorption spectroscopy technology is used to ensure the range and linearity, when the environmental concentration is high. At 25℃, standard atmospheric pressure, the measurement error of low concentration (<2%) is less than ±5.00×10-4, and the detection limit is 2.24×10-4. Under the condition of allowing baseline calibration or background subtraction, the limit could reach 6.026×10-5. The measurement error of high concentration (2~100%) is less than ±5% of the true value. At the ambient temperature of -40~60℃, 1.2% and 20% standard gases are used for the temperature performance test, respectively. The maximum relative measurement error are -3.3% and -3.15%, which fully met the requirement of national standards. It can be widely used in the urban comprehensive pipe corridor, gas station leakage monitoring, coal mine safety warning and other occasions.