期刊
MEASUREMENT SCIENCE AND TECHNOLOGY
卷 28, 期 6, 页码 -出版社
IOP PUBLISHING LTD
DOI: 10.1088/1361-6501/aa6a08
关键词
photoacoustic spectroscopy; wavelength stabilization; methane sensor
资金
- Early Career Scheme (ECS) from Research Grants Council [CUHK24208515]
- Innovation and Technology Fund of the Hong Kong Special Administrative Region, China [GHP/041/14]
A compact and portable photoacoustic gas sensor was developed for sensitive methane (CH4) detection at 1.6 mu m using a software-based wavelength stabilization scheme. A transmission-type photoacoustic cell was connected in series with a reference gas cell to measure the photoacoustic signal and the reference gas absorption for wavelength stabilization simultaneously. The central wavelength of the diode laser was locked to the target CH4 line with a fluctuation of less than 10.6 MHz using a digital proportional-integral-derivative controller. The CH4 sensor was designed to be insensitive to the incoherent external acoustic noise by the cumulative average of the demodulated photoacoustic signal by a digital lock-in amplifier. With an incident laser power of 6 mW, our CH4 sensor achieved a minimum detection limit of 11.5 ppm at 10 s response time and an excellent linearity (R-2 = 0.9999) in the concentration range of 400-6300 ppm.
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