Simultaneous detection of methane, oxygen and water vapour utilising near-infrared diode lasers in conjunction with difference-frequency generation

被引：0

作者：

U. Gustafsson

J. Sandsten

S. Svanberg

机构：

[1] Department of Physics,

[2] Lund Institute of Technology,undefined

[3] P.O. Box 118,undefined

[4] 22100 Lund,undefined

[5] Sweden (Fax: +46-46/222-4250,undefined

[6] E-mail: sune.svanberg@fysik.lth.se),undefined

来源：

Applied Physics B | 2000年 / 71卷

关键词：

PACS: 42.55.Px; 42.62.Fi; 42.65.Ky;

D O I：

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学科分类号：

摘要：

An all-diode-laser-based spectrometer is used for the simultaneous detection of methane, oxygen and water vapour. This is accomplished using a 760-nm diode laser and a 980-nm diode laser in conjunction with difference-frequency generation to 3.4 μm in a periodically poled lithium niobate crystal. Each of the output wavelengths is resonant with one of the molecular species. Simultaneous recordings over a 15-m open path of laboratory air are demonstrated. The recording scheme shows the wide applicability of a diode-laser-based difference-frequency spectrometer for the detection of molecular species in different wavelength ranges. By increasing the frequency of the 760-nm diode laser and decreasing the frequency of the 980-nm diode laser, a maximum continuous tuning range in the mid infrared of 3.6 cm-1 is achieved. This enables the recording of several methane lines at atmospheric pressure. Pressure-dependence studies of methane lineshapes are also performed in an absorption cell. An indoor-air methane background level of 3 ppm is measured. The signal-to-noise ratio in the recorded methane spectra indicates that sub-ppm detection of methane at atmospheric pressure is feasible.

引用

页码：853 / 857

页数：4