基于时域频域分析结合的调谐激光吸收光谱检测参数优化  

Detection parameters optimization of tunable laser absorption spectroscopy based on the combination of time domain and frequency domain analysis

作　　者：于永波 杜振辉[2,3] 高楠[1,3] 李金义[4] 孟召宗[1] 张宗华 YU Yongbo;DU Zhenhui;GAO Nan;LI Jinyi;MENG Zhaozong;ZHANG Zonghua(School of Mechanical Engineering,Hebei University of Technology,Tianjin 300130,China;State Key Laboratory of Precision Measuring Technology and Instruments,Tianjin University,Tianjin 300072,China;Key Laboratory of Micro Optical Eelectro Mechanical System Technology,Ministry of Education,Tianjin University,Tianjin 300072,China;Key Laboratory of Advanced Electrical Engineering and Energy Technology,Tiangong University,Tianjin 300387,China)

机构地区：[1]河北工业大学机械工程学院,天津300130 [2]天津大学精密测试技术及仪器国家重点实验室,天津300072 [3]天津大学微光机电系统技术教育部重点实验室,天津300072 [4]天津工业大学天津市电工电能新技术重点实验室,天津300387

出　　处：《光电子．激光》2023年第3期278-283,共6页Journal of Optoelectronics·Laser

基　　金：国家自然科学基金(61505142);河北省自然科学基金(F2014202065);微光机电系统技术教育部重点实验室(天津大学)开放基金资助项目。

摘　　要：随着调谐激光吸收光谱(tunable laser absorption spectroscopy,TLAS)技术在气体检测中的应用越来越广泛,二次谐波信号的质量与检测参数紧密相关,因而分析检测参数的优化方法很有意义。本文根据谱线预处理中的滤波参数、系统采样时间、锁相放大器的时间常数对信号的影响以及参数间的联系,总结检测参数的选取规律。根据滤波原理和不同浓度下信号的均方根误差(root mean squared error,RMSE)值选择合适的滤波阶数和窗宽。选择信噪比(signal-to-noise ratio,SNR)、RMSE、信号与噪声频域幅度之比(ratio of amplitude in frequency domain of signal to noise,fSNR)3种评价指标的曲线变化趋势进行时频分析,得到最佳采样周期数为30,结合实验系统具体参数可计算最佳采样时间。通过信号主频带与截止频率的关系和滤波效果选择合适的时间常数。综合分析3个检测参数并总结选取方法,可提高二次谐波信号的质量。本文提出的参数选取方法对提高二次谐波在实际应用中的准确度有重要意义。Tunable laser absorption spectroscopy(TLAS) technology has been widely used in gas detection.The quality of the second harmonic signal is closely related to the detection parameters. Therefore, it is very meaningful to analyze the optimization methods of detection parameters.This paper summarizes the selection rules of detection parameters according to the influence of the filter parameters in spectral line preprocessing, the sampling time of the system, and the time constant of the lock-in amplifier on the signal and the relationship between the parameters.The appropriate filter order and window width are selected according to the filtering principle and the root mean squared error(RMSE) value of the signal under different concentrations.The three evaluation indicators of signal-to-noise ratio(SNR),RMSE,and the ratio of amplitude in frequency domain of signal to noise(fSNR) are selected for time-frequency analysis to obtain the optimal sampling period value of 30 according to the trend of curves.The optimal sampling time can be calculated according to the specific parameters of the experimental system.The appropriate time constant is selected according to the relationship between the main frequency band of the signal and the cut-off frequency and the filtering effect.The quality of the second harmonic signal can be improved by comprehensive analyzing the three detection parameters and summarizing the selection method.The parameter selection method proposed in this paper is of great significance to improve the accuracy of the second harmonic in practical applications.

关 键 词：调谐激光吸收光谱(TLAS) 参数优化 时频分析 信号滤波 

分 类 号：O433.4[机械工程—光学工程]