基于宽带光源与相关光谱技术的CH4传感器研究

针对传统光学传感技术气体选择性不高与激光光源在气体检测中需严格控温的缺点,采用红外宽带光源进行CH4气体的检测,并结合实验所用气室与光电探测器件参数,利用HITRAN数据库对CH4吸收进行仿真计算,得出了系统理论探测下限与光强信号之间的变化规律。在不同CH4浓度梯度的实际测量中,采用快速傅里叶变换(FFT)与Savitzky-Golay数字滤波相结合的方法对系统噪声进行处理,将外部因素引起的噪声干扰降低了1个数量级,在不同CH4浓度梯度的实际测量中,利用CH4浓度和光强调制系数的对应关系对系统进行了标定,并通过数据拟合得到CH4浓度的反演曲线,相关系数达到0.998 83,测量灵敏度低至20×10-6,系统检测下限约为50×10-6;与传统化学传感器相比,系统测量误差小于1.5~7.0%,实现了CH4浓度的精确检测。

Study of CH4sensor based on a broadband light source and correlation spectro scopy

The correlation spectroscopy principle and the methane detection system ba sed on cheap infrared(IR) broadband light source are introduced in this paper,and methane spectral absorption simu lations for different concentrations are carried on by using HITRAN database.Combined with the parameters of a gas chambe r with a photodetector,the relationship between the system detection limit and light intensity is obtained.The system noise is processed by FFT coupled with Savitzky-Golay filtering algorithm during the actual measurement f or different methane concentration gradients,and the noise caused by external factors is reduced by one order of ma gnitude.The relationship between methane concentration and intensity modulation index is obtained by linear fitting,and the system can achieve precise results in methane detection.The measurement errors ranged from 1.5% to 7%,and accurate det ection to the methane concentration was achieved.