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Indexed by:期刊论文

Date of Publication:2021-01-10

Journal:IEEE TRANSACTIONS ON INSTRUMENTATION AND MEASUREMENT

Volume:69

Issue:10

Page Number:8486-8493

ISSN No.:0018-9456

Key Words:Fiber-optic acoustic detector; lock-in white-light interferometer (WLI); multigas analysis; photoacoustic spectroscopy (PAS)

Abstract:We present an all-optical photoacoustic (PA) multigas analyzer by using a digital fiber-optic acoustic detector, which consists of a spectrum demodulation based fiber Fabry-Perot (F-P) pressure sensor and a digital virtual lock-in amplifier. The concentration of multigas is quantified by using an intensity-modulated infrared thermal source and two wavelength-modulated laser diodes. Light beams from the three sources are coupled to a single nonresonant PA cell. The generated PA pressure is detected by the fiber F-P pressure sensor, which is demodulated by a near-infrared spectrometer. A lock-in white-light interferometer is developed for detecting first-harmonic (1f ) and second-harmonic (2f ) signals. The noise equivalent detection limits with a 100-s averaging time are 37, 9, 6, 17, 4, and 60 ppb for CH4, C2H2, C2H4, C2H6, CO, and CO2, respectively.