Accuracy and Etalon Fringe Phenomena in Methane-gas Spectrometry Employing Tunable Diode Lasers

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Abstract

A method to monitor atmospheric gas concentration employing a tunable diode laser is proposed. An apparatus was built and experiments were made. The tunable diode laser employed was of'PbSnTe with its wavenumber about 1200 cm(-1) at a temperature of 77 K. Methane concentration in laboratory atmosphere was measured on the experiments. The inquired gas-density is obtained by a hardwired microcomputer incorporating the measured absorption spectrum over a prescribed range instead of an absorption at a single wavenumber. By this, drift type noises are suppressed. After an analysis based on experimental data, an attainable sensitivity for methane was found to be 1 ppb.m. This value may increase if an etalon fringe interference exists. The natural concentration, about 1 ppm, of atmospheric methane was actually measured with a short optical path of only one meter.

Journal

  • Memoirs of the School of Engineering, Okayama University

    Memoirs of the School of Engineering, Okayama University 15(2), 79-92, 1981-03-30

    岡山大学工学部

Codes

  • NII Article ID (NAID)
    120002307246
  • NII NACSIS-CAT ID (NCID)
    AA00733903
  • Text Lang
    ENG
  • Article Type
    departmental bulletin paper
  • ISSN
    0475-0071
  • Data Source
    IR 
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