功率增强型的全光式QEPAS痕量气体检测系统研究
All-optical QEPAS trace gas senor employing an optical amplification technique
林成1
作者信息
- 1. 内江师范学院 物理与电子信息工程学院,四川 内江 641100
- 折叠
摘要
石英增强光声光谱技术由于具有灵敏度高、噪声免疫能力强、体积小等优点,成了一种备受关注的痕量气体检测技术.本文设计了一种全光式QEPAS痕量气体检测系统,采用共振频率为32.7 kHz的石英音叉作为声传感器,结合光功率放大技术,实现了系统信号幅值的极大提高;以具有工作点自稳定特性的光纤珐珀干涉仪作为振动解调单元,极大地提高了系统的稳定性.以C2H2作为检测对象,采用波长调制和二次谐波解调技术,优化得到系统的最佳调制深度为0.171 cm-1、最佳激光位置距离音叉底部2.9 mm,最终得到QEPAS信号随C2H2浓度线性变化,其线性度为0.998,系统检测极限为30.3 ppb,由此得到系统的归一化等效噪声系数为2.51 × 10-8 cm-1·W·Hz-1/2.最后在相同条件下,通过1小时连续工作测试验证了系统具有极好的稳定性.
Abstract
Quartz-Enhanced Photoacoustic Spectroscopy(QEPA)technology has become a kind of trace gas detection technology due to its advantages of high sensitivity,strong immunity to noise and compact size.An all-optical QEPA trace gas detection system was designed.A quartz tuning fork with a resonant frequency of 32.7 kHz was employed as the acoustic sen-sor,and the system signal amplitude was greatly enhanced by employing an optical power amplification technology.A fiber-op-tic Fabry-Perot interferometer with self-stabilizing characteristics was used as the vibration demodulation unit,significantly im-proving system stability.Acetylene(C2H2)was selected as the target gas for detection.A tunable semiconductor laser with a output wavelength of 1.5 μm was used as the excitation light source.By combining wavelength modulation and second harmon-ic demodulation techniques,the optimal modulation depth was determined to be 0.171 cm-1,and the optimal distance between the laser position and the bottom of the tuning fork was found to be 0.8 mm.The QEPAS signal exhibited linear variation with C2 H2 concentration,with a linearity of 0.998.The system detection limit was 30.3 ppb,corresponding to a normalized equiva-lent noise coefficient of 2.51×10-8 cm-1·W·Hz-1/2.Finally,under the same conditions,a continuous working test for one hour was conducted,verifying the excellent stability of the system.
关键词
石英增强光声光谱/功率增强/全光式/光纤珐珀解调/自稳定技术Key words
quartz-enhanced photoacoustic spectroscopy(QEPAS)/power amplification/all-optical/fiber-optic fabry-perot demodulation/self-stabilization technology引用本文复制引用
基金项目
四川省自然科学基金(2022NSFSC0525)
内江师范学院科研项目(2021ZD11)
出版年
2024
NETL
NSTL
万方数据