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High-sensitivity photoacoustic gas detector by employing multi-pass cell and fiber-optic microphone
Optics Express ( IF 3.8 ) Pub Date : 2020-02-20 , DOI: 10.1364/oe.382310
Bo Zhang , Ke Chen , Yewei Chen , Beilei Yang , Min Guo , Hong Deng , Fengxiang Ma , Feng Zhu , Zhenfeng Gong , Wei Peng , Qingxu Yu

A high-sensitivity photoacoustic (PA) spectroscopy (PAS) system is proposed for dual enhancement from both PA signal excitation and detection by employing a miniaturized Herriott cell and a fiber-optic microphone (FOM). The length of the optical absorption path of the PA cell is optimized to ∼374 mm with 17 reflections. The volume of the PA cell is only 622 µL. The FOM is a low-finesse fiber-optic Fabry-Pérot (FP) interferometer. The two reflectors of the FP cavity are formed by a fiber endface and a circular titanium diaphragm with a radius of 4.5 mm and a thickness of 3 µm. A fast demodulated white-light interferometer (WLI) is utilized to measure the absolute FP cavity length. The acoustic responsivity of the FOM reaches 126.6 nm/Pa. Several representative PA signals of trace acetylene (C2H2) are detected to evaluate the performance of the trace gas detector in the near-infrared region. Experimental results show that the minimum detectable pressure (MDP) of the FOM is 3.8 µPa/Hz1/2 at 110 Hz. The noise equivalent minimum detection concentration is measured to be 8.4 ppb with an integration time of 100 s. The normalized noise equivalent absorption (NNEA) coefficient is calculated as 1.4×10−9 cm−1·W·Hz−1/2.

中文翻译:

采用多通道单元和光纤麦克风的高灵敏度光声气体检测仪

提出了一种高灵敏度光声(PA)光谱系统(PAS),该系统通过使用微型Herriott单元和光纤麦克风(FOM)来实现PA信号激发和检测的双重增强。通过17次反射,PA电池的光吸收路径长度被优化为〜374 mm。PA电池的体积仅为622 µL。FOM是一种低精细光纤法布里-珀罗(FP)干涉仪。FP腔的两个反射器由一个纤维端面和一个半径为4.5 mm,厚度为3 µm的圆形钛膜制成。快速解调的白光干涉仪(WLI)用于测量FP腔的绝对长度。FOM的声响应率达到126.6 nm / Pa。痕量乙炔(C 2 H 2进行检测以评估痕量气体检测仪在近红外区域的性能。实验结果表明,在110 Hz下,FOM的最小可检测压力(MDP)为3.8 µPa / Hz 1/2。噪声等效最小检测浓度经测量为8.4 ppb,积分时间为100 s。归一化噪声等效吸收(NNEA)系数被计算为1.4×10 -9 cm -1 ·W·Hz -1/2
更新日期:2020-03-02
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