痕量N2O气体检测系统的设计与实现

建立了基于光谱吸收技术的检测系统,用于快速、准确地测量N2O气体浓度。首先,从理论上证明了二次谐波、一次谐波与N2O气体浓度之间的关系;然后,设计了痕量N2O气体浓度检测系统,利用光源调制、锁相放大等技术,实现了强杂波背景下气体浓度弱信号的解析;最后,实验测试了系统的检测性能、抗干扰能力及检测结果的可重复性。测试结果表明,系统能够在0～1%有效检测N2O气体浓度,检测下限为5.0×10-5,相对检测误差为0.11%,检测结果线性方程为Y=192.699 09 X-0.006 24,线性度为0.998 07。多次检测实验表明,系统相对标准偏差为0.137%,CO2、O2、水蒸气等常见气体对检测结果无影响。改变激光器的中心波长,该方法亦可用于CO2,CH4等其它温室气体的检测。

Design and implementation of trace N2O detection system

A measurement system based on the spectral absorption was established to measure the N2O concentration accurately.First, the relationship of the second-harmonic, the first-harmonic with N2O gas concentration was demonstrated in theory. Then, a N2O detection system for trace concentration was designed based on a Distribute Feedback Laser(DFB).By using the light modulation and lock-in amplifier technologies, weak gas concentration signals in the strong clutter background were analyzed. Finally, the detection performance, anti-jamming capability and the repeatability of test results were verified through experiments. Test results indicate that the system can offer the measuring range from 0 to 1%, detection limit of 5.0×10-5,and the relative detection error of 0.11%. Furthermore,the linear equation is Y=192.699 09X- 0.006 24, the linearity is 0.998 07,and the relative standard deviation is 0.137%.It also proves that the CO2, O2, water vapor, et al. have no effect on the experimental results. By changing the centre wavelength of the laser,the system can be used in the detection of other greenhouse gases, such as CO2 and CH4.