斩波器研制及其应用于光声光谱测量CO_(2)的研究  

Development of a Homemade Chopper and Its Application to Photoacoustic Spectroscopy for CO_(2) Measurement

作　　者：彭杰 王瑞峰[1] 曹渊 梅教旭 王贵师 刘锟 高晓明 程刚 PENG Jie;WANG Rui-feng;CAO Yuan;MEI Jiao-xu;WANG Gui-shi;LIU Kun;GAO Xiao-ming;CHENG Gang(Anhui Institute of Optics and Fine Mechanics,Hefei Institutes of Physical Science,Chinese Academy of Sciences,Hefei 230031,China;University of Science and Technology of China,Hefei 230026,China;State Key Laboratory of Ming Response and Disaster Prevention and Control in Deep Coal Mines(Anhui University of Science and Technology),Huainan 232001,China)

机构地区：[1]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230031 [2]中国科学技术大学,安徽合肥230026 [3]安徽理工大学,深部煤矿采动响应与灾害防控国家重点试验室,安徽淮南232001

出　　处：《光谱学与光谱分析》2024年第12期3364-3370,共7页Spectroscopy and Spectral Analysis

基　　金：国家自然科学基金项目(42205133,41575030,62105005)资助。

摘　　要：在光声光谱中,产生光声信号的必要条件之一就是需要对光源进行周期性的调制。针对一些光源,如宽带光声光谱所用的红外热辐射光源,对其进行调制只能通过机械斩波的方式实现。然而商用的斩波器由于存在体积较大、成本高昂等问题,无法适用于小型化光声光谱仪的应用。本文开展了光学斩波器的设计研发及其应用于光声光谱系统探测二氧化碳(CO_(2))的研究。首先基于STM32单片机技术设计了斩波器控制电路,开展了自制斩波器与商业斩波器的对比测试实验。测量结果表明两者产生的光声信号具有很好的一致性,验证了研制的光学斩波器的可靠性,使其能够满足光声光谱系统的应用需求。然后基于研制的光学斩波器开展了光声光谱探测CO_(2)的研究,分析了湿度对CO_(2)光声信号的影响。研究表明水汽会明显加速CO_(2)的分子弛豫速率,从而明显改善CO_(2)的光声信号幅值。Allan方差分析表明,在平均时间为200 s时,光声光谱系统对CO_(2)的检测灵敏度为5μL·L^(-1)。相比于加湿前的CO_(2)探测极限,加湿后的CO_(2)最低检测限提高了2.4倍。研制的斩波器具有体积更小、成本低廉的优势,对研发高灵敏度光声光谱仪器具有参考或应用价值。In photoacoustic spectroscopy,periodic modulation of light sources is one of the necessary conditions for generating photoacoustic signals.The modulation can only be realized using mechanical choppers for some light sources,such as infrared radiation sources applied in broadband photoacoustic spectroscopy.However,a commercial chopper is unsuitable for miniaturized photoacoustic spectroscopy instruments due to its large size and high cost.In this paper,we carried out the design and development of a homemade chopper and its application to carbon dioxide(CO_(2))detection by photoacoustic spectroscopy.The chopper control circuit was designed based on the STM32 microcontroller technology,and a comparison experiment between the homemade chopper and the commercial chopper was conducted.The experimental results showed that the photoacoustic signals produced by both had a good consistency,verifying the feasibility and reliability of the homemade chopper,which can satisfy the application requirements of photoacoustic spectroscopy.Then,the research of photoacoustic spectroscopy for measuring CO_(2) was carried out based on the homemade chopper,and the effect of humidity on the CO_(2) photoacoustic signal was analyzed.It has been shown that water vapor significantly accelerates the molecular relaxation rate of CO_(2),thus improving the amplitude of the photoacoustic signal of CO_(2).The Allan deviation result showed that the detection sensitivity for CO_(2) of the photoacoustic spectroscopy system was found to be 5μL·L^(-1) at an average time of 200 s.Compared with the CO_(2) before humidification,the minimum detection limit of CO_(2) was improved by a factor of 2.4 after humidification.The homemade chopper is characterized by easy integration and has reference or application value for developing high-sensitivity photoacoustic spectroscopy instruments.

关 键 词：光声光谱 光学斩波器 二氧化碳 痕量气体 

分 类 号：O433.5[机械工程—光学工程]