基于中红外LED的二氧化碳光声检测  

Photoacoustic Detection of CO_(2)Based on Mid-Infrared LED

作　　者：李振钢 司赶上 宁志强 刘家祥 方勇华 程真 斯贝贝 杨长平 Li Zhengang;Si Ganshang;Ning Zhiqiang;Liu Jiaxiang;Fang Yonghua;Cheng Zhen;Si Beibei;Yang Changping(Key Laboratory of Environmental Optics and Technology,Anhui Institute of Optics and Fine Mechanics,Hefei Institutes of Physical Science,Chinese Academy of Sciences,Hefei 230031,Anhui,China;University of Science and Technology of China,Hefei 230026,Anhui,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环境光学与技术重点实验室,安徽合肥230031 [2]中国科学技术大学,安徽合肥230026

出　　处：《光学学报》2022年第13期206-215,共10页Acta Optica Sinica

基　　金：国家自然科学基金(61875207);中科院科研仪器设备研制项目(YJKYYQ20190050);安徽省杰出青年科学基金(1908085J23)。

摘　　要：气体检测在众多领域发挥着重要作用。光声光谱技术具有高灵敏度、响应快速等优点,广泛满足各种气体检测需求。基于光声光谱技术,以中心波长为4300 nm的中红外LED替代激光器作为二氧化碳气体的激发光源。结合长光程与声共振技术,研制了一种T型光声池,其吸收池内壁镀金,池体上耦合了一根声共振管。利用有限元仿真得到了光声池的一阶纵向共振模态及共振频率。为了实现LED光源的调制输出,设计了硬件驱动电路。基于上述工作,搭建了一套自动化流程的二氧化碳气体光声检测装置。实验结果表明,光声信号与样品浓度之间具有良好的线性度,噪声等效浓度(体积分数)为1.24×10^(-4)。使用Allan偏差评估装置的稳定性,当平均时间为200 s时,装置的检测灵敏度为1.8×10^(-5)。Gas detection plays an important role in many fields.Due to its advantages of high sensitivity and fast response,photoacoustic spectroscopy readily meets various gas detection needs.Based on the photoacoustic spectroscopy,this paper uses a mid-infrared LED with a central wavelength of 4300 nm instead of using a laser as the excitation light source of carbon dioxide gas.The technologies of long optical paths and acoustic resonance are exploited to develop a T-type photoacoustic cell that has an absorption cell with a gold-plated inner wall and an acoustic resonance tube coupled to its body.The first-order longitudinal resonance mode and resonance frequency of the photoacoustic cell are obtained through finite-element simulation.For a modulated output from the LED light source,a hardware drive circuit is designed.On the basis of the above work,a photoacoustic detection setup for carbon dioxide gas with an automated process is built.Experimental results reveal favorable linearity between photoacoustic signals and sample concentrations,and the noise-equivalent concentration(volume fraction)is 1.24×10^(-4).The Allan deviation is used to evaluate the stability of the setup.When the average time is 200 s,the detection sensitivity of the setup is 1.8×10^(-5).

关 键 词：光谱学 检测 光声光谱技术 中红外LED 二氧化碳 光声池 

分 类 号：TP23[自动化与计算机技术—检测技术与自动化装置]