3.93μm激光外差光谱系统光学结构设计与N_(2)O测量  

Optical Structure Design of 3.93μm Laser Heterodyne Spectrometer and N_(2O)Measurement

作　　者：张天民 黄俊 黄尧 齐刚 袁子豪 曹振松 黄印博 饶瑞中[2,4] 卢兴吉 Zhang Tianmin;Huang Jun;Huang Yao;Qi Gang;Yuan Zihao;Cao Zhensong;Huang Yinbo;Rao Ruizhong;Lu Xingji(School of Environmental Science and Optoelectronic Technology,University of Science and Technology of China,Hefei 230026,Anhui,China;Key Laboratory of Atmospheric Optics,Anhui Institute of Optics and Fine Mechanics,HFIPS,Chinese Academy of Sciences,Hefei 230031,Anhui,China;Science Island Branch of Graduate School,University of Science and Technology of China,Hefei 230026,Anhui,China;Advanced Laser Technology Laboratory of Anhui Province,Hefei 230037,Anhui,China)

机构地区：[1]中国科学技术大学环境科学与光电技术学院,安徽合肥230026 [2]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,中国科学院大气光学重点实验室,安徽合肥230031 [3]中国科学技术大学研究生院科学岛分院,安徽合肥230026 [4]先进激光技术安徽省实验室,安徽合肥230037

出　　处：《中国激光》2023年第14期216-225,共10页Chinese Journal of Lasers

基　　金：国家自然科学基金重大科研仪器研制项目(42027804);先进激光技术安徽省实验室青年基金(AHL2021QN01)。

摘　　要：激光外差光谱(LHS)系统具有光谱分辨率高、探测灵敏度高和体积小等特点,在高分辨率太阳光谱和整层大气透过率测量等应用中受到关注。以3.93μm分布反馈式带间级联激光器(DFB-ICL)作为本振光源搭建了激光外差光谱测量系统,以太阳光作为信号光,利用Zemax光学仿真软件对太阳光与激光的耦合进行设计和仿真。基于开普勒望远镜原理设计了太阳光整形结构。光斑整形后有效提高了外差耦合效率,将系统信噪比提高至162.1,比无整形条件下获得的信噪比提高了一倍。利用搭建的激光外差系统实测了合肥地区整层大气N_(2)O吸收光谱,采用最优估算法反演了N_(2)O的柱浓度,均值为0.311×10^(-6),反演结果与EM27/SUN的实测结果进行比较,两种方式获得的N_(2)O柱浓度相关性为0.856。测量结果表明,激光外差光谱测量系统的光学结构经设计和优化后,光学耦合效率和系统信噪比均得到有效提升,基于实测太阳光谱反演获得的N_(2)O柱浓度也与商用仪器观测结果具有较好的一致性。Objective Laser heterodyne spectrum measurement technology has the characteristics of high spectral resolution,high detection sensitivity and short sampling time.This technology can not only obtain the high-resolution spectral information of the whole layer of atmospheric molecules,but also facilitate the observation of gas concentration in different scenarios due to its small size and easy integration.Therefore,it has been widely concerned by researchers.At present,domestic research on laser heterodyne spectrum measurement system mainly focuses on solar tracking,spectral resolution and inversion algorithm.Due to the low power of the detection signal received by the heterodyne system,the signal-to-noise ratio(SNR)of the heterodyne system is low in actual operation.Therefore,based on the principle of Kepler telescope,a set of sunlight beam shaping structure is designed to improve the sunlight power,and the system SNR is improved by matching the size of the two beams.Methods In this paper,a 3.93μm distributed feedback interband cascade laser(DFB-ICL)is used as the local oscillator light source to build a laser heterodyne spectrum measurement system,and sunlight is used as the signal light.The coupling of sunlight and laser is designed and simulated by Zemax optical simulation software.In the experiment,considering the distance between the shaping lens and the photosensitive surface of the detector,the coupling efficiency and the performance of the detector,the incident sunlight diameter is set to 4.5 mm,the plane-convex lens 1 with a focal length of 750 mm and the plane-convex lens 2 with a focal length of 500 mm are selected to form the Kepler telescope structure for shaping the sunlight.The absorption spectrum of N_(2)O in the range of 2542.9-2545.0 cm^(-1)is measured by studying the beam reduction rule of the sunlight and the SNR of the system.The optimal estimation method is used to inverse the measured spectra,and the N_(2)O column concentration is obtained.Finally,the inversion results of the laser heterodyn

关 键 词：光谱学 激光外差 信噪比 光斑整形 光学仿真 反演算法 

分 类 号：O433.1[机械工程—光学工程]