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Proceedings Paper

NIR diode laser-based QEPAS for acetylene detection
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Paper Abstract

Quartz-enhanced photoacoustic spectroscopy with a near infrared distributed feedback diode laser at 1.53 μm is demonstrated for acetylene detection at atmospheric pressure and room temperature. The P(9) absorption line in the ν13 band of C2H2 is selected for light absorption and photoacoustic pressure wave excitation. A pair of resonant tubes with optimal dimensions is used in combination with a quartz tuning fork for photoacoustic signal enhancement. The wavelength of diode laser is modulated at half of the resonant frequency of tuning fork for second harmonic signal detection. The effect of residual amplitude modulation is theoretically analyzed and compared with the experimental results. A noise-limited minimum detectable concentration (1σ) of 2 part-per-million (ppm) is achieved with a 7-mW laser power and a 1-s lock-in time constant, corresponding to a normalized noise equivalent absorption coefficient of 5.4×10-8 cm-1 W/√Hz.

Paper Details

Date Published: 9 May 2012
PDF: 7 pages
Proc. SPIE 8439, Optical Sensing and Detection II, 843928 (9 May 2012); doi: 10.1117/12.922625
Show Author Affiliations
Yingchun Cao, The Hong Kong Polytechnic Univ. (Hong Kong, China)
Wei Jin, The Hong Kong Polytechnic Univ. (Hong Kong, China)
Hoi Lut Ho, The Hong Kong Polytechnic Univ. (Hong Kong, China)

Published in SPIE Proceedings Vol. 8439:
Optical Sensing and Detection II
Francis Berghmans; Anna Grazia Mignani; Piet De Moor, Editor(s)

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