Impact of Resonance Frequency of Quartz Tuning Fork on QEPAS-Based Sensors
LI Biao1, 2, DONG Lei1, 2, WU Hong-peng1, 2*
1. State Key Laboratory of Quantum Optics and Quantum Optics Devices, Institute of Laser Spectroscopy, Shanxi University, Taiyuan 030006, China
2. Collaborative Innovation Center of Extreme Optics, Shanxi University, Taiyuan 030006, China
Abstract：Quartz-enhanced photoacoustic spectroscopy (QEPAS) based spectrophone has developed rapidly in recent years. With the benefit of a quartz tuning fork (QTF), the QEPAS technique offerscompact structure and low sensitivity to surrounding noise. However, it’s difficult to use the standard QTF for slowly relaxing gas molecule detection as the high resonance frequencyof QTF. And it is a big challenge touse the laser with low beam quality as the excitation light sources of the QEPAS system because the gap size between the prongs of the standard QTF is too narrow. Non-standard QTFs (f0≠32.768 kHz) have been installed in QEPAS system as acoustic transducer in recent years. Therefore, the influence of the resonance frequencies of QTFs on the QEPAS system performance must be studied in detail. In this paper, the water vapor was used as the target gas and was detected via different QEPAS-based gas sensors in which the four QTFs with different resonance frequencies were installed as the acoustic transducer. The experimental results show that the resonant frequency of the QEPAS acoustic transducer has a significant effect on the signal-to-noise ratio of the QEPAS system. The reported results are extremely useful in the design of the QEPAS spectrophone.
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