Abstract
In order to achieve a high sensitivity with a tunable diode absorption spectrometry, it is necessary to suppress parasitic spectral interference as well as white noise. Optical, tailoring souce-frequency modulation profile and dataprocessing methods were examined. Optically, employing a quarter wave plate and defocusing were effective. The tailoring the source-frequency modulation profile in the higher harmonic detection method reduces the unnecessary system-response to a fine-pitched etalon fringes. The numerical process makes the system insensitive to a baseline distortion. Experimentally, contribution of etalon fringe to a fluctuation of measured atmospheric methane were reduced down to about 5 ppb.m(rms) which is less than the level determined by the white noise caused by infrared detector.
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References
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© 1989 ECSC, EEC, EAEC, Brussels and Luxembourg
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Koga, R. (1989). Absorption Spectrometry for Atmospheric Methane: Techniques for Higher Sensitivity. In: Grisar, R., Schmidtke, G., Tacke, M., Restelli, G. (eds) Monitoring of Gaseous Pollutants by Tunable Diode Lasers. Springer, Dordrecht. https://doi.org/10.1007/978-94-009-0989-2_14
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DOI: https://doi.org/10.1007/978-94-009-0989-2_14
Publisher Name: Springer, Dordrecht
Print ISBN: 978-94-010-6934-2
Online ISBN: 978-94-009-0989-2
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