近红外激光二氧化碳传感系统的研制及应用

Development and Application of Near-Infrared Laser Carbon Dioxide Gas Sensor System

采用可调谐激光二极管吸收光谱技术,研制了一种近红外激光二氧化碳(CO2)传感系统。该系统包含中心波长为1572 nm的分布反馈激光器、密集光斑型气室和铟镓砷探测器,利用LabVIEW程序提取二次谐波信号幅值并反演了CO2浓度。为了表征传感器性能,利用该系统开展了气体检测实验。结果显示,当调制深度为0.32 cm-1时,二次谐波信号的幅值最大;在体积分数为0~3%范围内,二次谐波信号的幅值与CO2浓度具有较高的线性度(拟合优度为0.999);当CO2体积分数为0时,连续测试1 h,反演得到的浓度波动范围为-2×10-4~1.17×10-4;当积分时间为297 s时,系统的灵敏度检测下限为2.7×10-6;考虑动态配气时气体的扩散时间,系统的响应时间为40~42 s;连续15 h测量室内大气中CO2浓度,测得的CO2平均体积分数约为(560±46)×10-6。与已经报道的传感器相比,该气体传感系统呈现出类似的品质因数,可在工农业生产、环境保护等领域得到一定的推广和应用。

A near-infrared laser carbon dioxide(CO2) sensor system is developed using tunable diode laser absorption spectroscopy(TDLAS). The system consists of a distributed feedback laser with a central wavelength of 1572 nm, a dense spot-type gas chamber, and an indium gallium arsenic detector. LabVIEW program is used to extract the amplitude of the second harmonic signal and the CO2 concentration is inverted. In order to characterize the sensor performance, gas detection experiments are carried out by using the system. The results show that,when the modulation depth is 0.32 cm-1, the amplitude of the extracted second harmonic signal is the largest. In the volume fraction range of 0--3%, the amplitude of the second harmonic signal has a high linearity with the CO2 concentration(the goodness of fit is 0.999). When the volume fraction of CO2 is 0, the retrieved concentration fluctuation range is-2×10-4--1.17×10-4 after continuous test for 1 h. When the integral time is 297 s, the lower limit of sensitivity detection of the system is 2.7×10-6. Considering the gas diffusion time during dynamic gas distribution, the response time of the system is 40--42 s. The CO2 concentration in the atmosphere is measured continuously for 15 h, and the average CO2 volume fraction measured is about(560±46)×10-6. Compared with the reported sensors, the gas sensing system presents similar quality factors and can be popularized and applied in industrial and agricultural production, environmental protection and other fields.