中国激光, 2020, 47 (1): 0111002, 网络出版: 2020-01-09
基于光声光谱技术的CO气体探测 下载: 1597次
Carbon Monoxide Detection Based on Photoacoustic Spectroscopy
摘要
搭建了基于2.3 μm中红外可调谐二极管激光器的CO气体的光声光谱测量系统,并选取4300.699 cm -1处的CO吸收谱线作为传感目标。为了消除较长的CO分子弛豫时间对测量的影响,采用在实验气体中混入水汽的方式来增强光声信号。通过优化调制参数确定出系统的最佳调制振幅和调制频率分别为4.29 cm -1和785 Hz。在最优的实验条件下,所选谱线的二次谐波信号与CO浓度间具有良好的线性关系,其线性度为0.994,利用该关系反演出空气中CO的体积分数约为2.13×10 -6。最后利用Allan方差对干湿条件系统的长期稳定性进行了分析,得到系统在干湿条件下的探测极限分别为1.18×10 -7和0.58×10 -7,验证了水汽的加入可以有效提高系统对CO的探测灵敏度。
Abstract
A carbon monoxide (CO) measurement system based on photoacoustic spectroscopy with a 2.3 μm mid-infrared tunable diode laser is built. The CO absorption line at 4300.699 cm -1 is selected as the sensing object. In order to eliminate the influence of long relaxation time of CO molecule on measurement, water vapor is added into experimental gas to enhance CO photoacoustic signal. By optimizing the modulation parameters, the optimal modulation amplitude and modulation frequency of the system are determined to be 4.29 cm -1 and 785 Hz,respectively. Under the optimal experimental conditions, there is a good linear relationship between the second harmonic signal of the selected spectral line and the CO concentration, and the linearity is 0.994. The 2.13×10 -6 volume fraction of CO in the air can be retrieved from the relationship. Finally, by using the Allan variance to analyze the long-term stability of the system under dry and wet conditions, the detection limits under dry and wet conditions are 1.18×10 -7 and 0.58×10 -7, respectively. It is proved that the addition of water vapor can effectively improve the CO detection sensitivity of the system.
刘新, 张婷, 张刚, 高光珍, 蔡廷栋. 基于光声光谱技术的CO气体探测[J]. 中国激光, 2020, 47(1): 0111002. Xin Liu, Ting Zhang, Gang Zhang, Guangzhen Gao, Tingdong Cai. Carbon Monoxide Detection Based on Photoacoustic Spectroscopy[J]. Chinese Journal of Lasers, 2020, 47(1): 0111002.