基于虚拟锁相放大器的中红外CO检测系统  

A mid-infrared carbon oxide detection system based on virtual lock-in amplifier technology

作　　者：宋楠[1] 隋越[1] 董明[1] 李国林[1] 郑传涛[1] 王一丁[1] 

机构地区：[1]吉林大学电子科学与工程学院,集成光电子学国家重点联合实验室吉林大学实验区,吉林长春130012

出　　处：《光电子．激光》2014年第12期2343-2349,共7页Journal of Optoelectronics·Laser

基　　金：国家科技支撑计划(2013BAK06B04;2014BAD08B03);国家自然科学基金(61307124);吉林省科技发展计划(20120707;201101036);长春市国际合作(11GH01)资助项目

摘　　要：利用PC机和LabVIEW平台较强的数据处理能力,设计并实现了一种基于虚拟锁相放大器的中红外CO检测系统。系统采用双通道热释电探测器检测气体浓度,利用USB数据采集卡采集探测器的传感信号,利用LabVIEW平台的乘法器、滤波器及直流幅值提取模块构建的虚拟锁相放大器提取传感信号幅度。为了表征虚拟锁相放大器的性能,利用幅度可调的标准正弦信号作为待测信号,对虚拟锁相放大器输出信号的幅度与标准正弦信号的幅度做实验测量与对比,二者呈现出良好的线性关系,线性拟合优度约为99.978%。对配备的20种CO气体样品开展气体标定实验,并测量了本文系统的精度、稳定性和检测下限等指标。实验结果显示,系统的检测下限约为50×10-6,对20种气体样品的检测误差均小于4.2%,对浓度为3 500×10-6气体样品3h测量结果的最大波动范围为±6%。由于LabVIEW资源丰富且功能可任意扩展,因此在实验室环境中的气体检测,本文系统相比采用嵌入式微处理器的系统更具有优势。A mid infrared carbon monoxide （CO） gas detection system based on virtual lock phase ampli fication technology is implemented by using the powerful data processing capabilities of personal computer and LabVIEW platform. In this paper,a dual-channel pyroeleetric detector is used to detect the gas concentration, a universal serial bus （USB） data acquisition card is used to sample the sensing signal, and a virtual lock-in amplifier, which is constructed by the multipliers, filters and direct current amplitude extraction module of LabVIEW, is used to derive the amplitude of the sensing signal. By using standard sine-wave signals with tunable amplitudes as the signals to be measured, the amplitudes of the output signals from the fabricated lock-in amplifier and the standard amplitudes are both tested and compared, and the linear fitting factor is up to 99. 978%. Gas calibration experiments are carried out using the detection system and the prepared 20 CO gas samples, and the accuracy, stability and detection limit of the system are measured. Experimental results show that the detection limit is about 50× 10^-6 ,the relative detection errors on the 20 gas samples are less than 4. 2% ,and the three-hour longterm detection on the 3 500× 10^-6 CO gas samples indicates a variation range of ± 6%. Due to rich resources and scalable functions of LabVIEW, this system shows superior advantages in gas detection under laboratory environment as compared with the detection system based on embedded microprocessor.

关 键 词：红外气体检测 USB数据采集卡 LABVIEW 虚拟锁相放大器 

分 类 号：TN911.72[电子电信—通信与信息系统] O659.21[电子电信—信息与通信工程]