摘要
作为传统激光光声光谱的改进和演变,石英增强光谱(QEPAS)具有探测灵敏度高、噪声免疫强、体积小和价格低等特点.本文设计了一种用于乙炔痕量气体检测的双光程离轴石英增强光声光谱系统,利用直角三棱镜将激发光束穿过两个声微共振管,采用正交相位点自稳定光纤法珀干涉仪作为音叉振动解调单元,结合波长调制和二次谐波解调技术,实现了光声信号、信噪比和系统稳定性的大幅提高;进一步优化了微共振管的空间位置、微共振管结构等传感系统的最优参数,得到系统的最小探测灵敏度为1.99 mg·m^(-3),对应的归一化噪声等效系数为7.6×10^(-8)cm^(-1)·W·Hz^(-1/2);在116~5812 mg·m^(-3)范围内,光声信号与乙炔浓度具有良好的线性关系,其线性度为0.998.
As an improvement and a variant of the conventional photoacoustic spectroscopy(PAS),the quartz-enhanced photoacoustic spectroscopy(QEPAS)offers a high sensitivity,strong immunity to ambient noise,compact volume and low cost.A double-pass off-beam QEPAS system for acetylene(C 2 H 2)detection was proposed.To enhance the QEPAS signal,it employed two AmRs and a right-angle prism to construct a double-pass enhancement channel.To enhance the signal to noise ratio(SNR)and stability,an optical fiber Fabry-Perot interferometric sensor with quadrature point self-stabilization was used as the sensor for the detection of quartz prong vibration and a wavelength modulation and a 2nd harmonic demodulation technology were employed.Experimentally,the parameters,including the AmR’s position and the OTF structure,were optimized.The experimental results demonstrated that the minimum detection limit was~1.99 mg·m^(-3)with a 1s averaging time,which corresponded to a normalized noise equivalent absorption coefficient of 7.6×10^(-8)cm^(-1)·W·Hz^(-1/2).In addition,a good linear dependence of the 2f-signal on the C 2 H 2 concentration within the range from 116 mg·m^(-3)to 5812 mg·m^(-3)was obtained and the linear correction coefficient was 0.998.
作者
林成
LIN Cheng(School of Educational Science College of Physics and Electronic Information Engineering,Neijiang Normal University,Neijiang,Sichuan 641100,China)
出处
《内江师范学院学报》
CAS
2023年第8期55-60,共6页
Journal of Neijiang Normal University
基金
四川省自然科学基金项目(2022NSFSC0525)
内江师范学院科研项目(2021ZD11)。
关键词
痕量气体检测
石英增强光声光谱
双光程
光纤法珀干涉仪
all-optcial
quartz-enhanced photoacoustic spectroscopy
self-stabilization
Fabry-Perot interferometer
