基于半球形声学共振腔的光声光谱气体传感系统研究  

Research on Gas Sensing System Using Photoacoustic Spectroscopy Based on a Hemispherical Acoustic Resonant Cavity

作　　者：王高旋 丁志华 高晓明 WANG Gao-xuan;DING Zhi-hua;GAO Xiao-ming(Ningbo Innovation Center,College of Optical Science and Engineering,Zhejiang University,Ningbo 315100,China;School of Information Science and Engineering,Ningbo Tech University,Ningbo 315100,China;Ningbo Nuclear Core Optoelectronic Technology Co.,Ltd.,Ningbo 315100,China;Anhui Institute of Optics and Fine Mechanics,Hefei Institutes of Physical Science,Chinese Academy of Sciences,Hefei 230026,China)

机构地区：[1]浙江大学宁波科创中心,浙江大学光电科学与工程学院,浙江宁波315100 [2]浙大宁波理工学院,浙江宁波315100 [3]宁波核芯光电科技有限公司,浙江宁波315100 [4]中国科学院合肥物质科学研究院,安徽光学精密机械研究所,安徽合肥230026

出　　处：《光谱学与光谱分析》2025年第3期608-615,共8页Spectroscopy and Spectral Analysis

基　　金：宁波市自然科学基金项目(2022J159);国家自然科学基金项目(62305290);浙江省自然科学基金项目(LQ22F050014)资助。

摘　　要：声学共振腔是光声吸收光谱技术的重要器件,相比于传统使用的圆柱形声学共振腔,球形声学共振腔具有体积小、品质因数高、更易提高气体吸收路径等优点。为进一步减小声学共振腔体积,实现微型化声学共振腔,本文首次报道了一种基于半球形声学共振腔的光声光谱气体传感系统,该半球形声学共振腔半径为15 mm,容积为7.07 mL。通过理论仿真和实验测试验证,测量出半球形声学共振腔的频率响应曲线,进一步确定了半球形声学共振腔的最佳工作频率和麦克风位置。为进一步提高光声光谱气体传感系统性能,通过增大声学共振腔的光线入射口尺寸,与多通池相耦合在一起,进一步增加气体吸收路径。多通池由两个反射镜构成,反射镜直径为25.4 mm,曲率半径为100 mm,距离20 cm,反射镜面上反射光斑为单线点模式,最终通过使用多通池提高了6倍的甲烷光声吸收信号幅值和4倍的甲醛光声吸收信号幅值。通过使用多麦克风方法,将光声光谱信号幅值提升了4倍。最终,光声光谱仪器耦合了发射波长位于1653和3640 nm的两个可调谐激光器,两个激光器通过不同位置入射至声学共振腔中,实现了甲烷和甲醛两种气体的测量,检测灵敏度为2.11×10^(-6)(20 s)和0.71×10^(-6)(20 s)。通过测量不同甲烷浓度下光声信号校准了光声光谱系统,实验结果表明光声信号与气体浓度具有良好的线性关系。通过使用Allan标准差方法评估光声光谱系统在长时间工作下的仪器稳定性,在仪器最佳积分时间660 s,甲烷检测灵敏度提升至0.4×10^(-6)。半球形声学共振腔由于其良好的光源适用性、体积小等特点,在光声光谱气体传感领域具有良好的应用前景。Acoustic resonant cavity is an important element in photoacoustic absorption spectroscopy.The spherical acoustic resonant cavity is widely reported to have the advantages of small volume,high-quality factor,and easier improvement of gas absorption path compared with a traditional cylindrical acoustic resonator.To further reduce the cavity volume and realize the miniaturization of the cavity,this paper first reports a gas sensing system using photoacoustic spectroscopy based on a hemispherical acoustic resonant cavity with a radius of 15 mm and a volume of 7.07 mL.The frequency response of the cavity was characterized to optimize the operating frequency and microphone position through theoretical simulation and experimental verification.To further improve the performance of the photoacoustic spectroscopy gas sensing system,the gas absorption path is further enhanced by combining with a multi-pass cell by increasing the light inlet dimension of the acoustic resonant cavity.The multi-pass cell comprises two mirrors with a diameter of 25.4 mm,a radius of 100 mm,and a distance of 20 cm,which results in a light spot of single line mode on the mirror surface.The photoacoustic signal amplitude of methane and formaldehyde were enhanced by 6 and 4 times,respectively.Using a multi-microphone method,the photoacoustic signal was increased by four times.The developed photoacoustic spectrometer was coupled to two tunable lasers emitting at 1653 and 3640 nm,which were irradiated into the cavity in two opposite directions to realize dual-gas detection(methane and formaldehyde)with measurement sensitivity of 2.11×10^(-6)(methane,20 s)and 0.71×10^(-6)(formaldehyde,20 s),respectively.The photoacoustic spectroscopy system was calibrated by measuring different methane concentrations,which showed a good linear relationship between photoacoustic signal and methane concentration.Allan s standard deviation method was used to evaluate the instrument stability of the photoacoustic spectroscopy system under long-term operation.The methane

关 键 词：光声光谱 半球形声学共振腔 气体传感 甲烷 甲醛 

分 类 号：O433.1[机械工程—光学工程]