雾霾对基于弹光调制检测系统的影响

近几年我国的雾霾日趋严重,不但对人的健康造成危害、对空中交通造成安全隐患,同时也对很多应用于户外的光学设备造成了影响。为了定量分析不同雾霾等级对基于弹光调制痕量气体浓度检测系统性能的影响,设计了一种测试系统,定量比较了在同一系统中不同PM2.5浓度条件下对等量VOC气体浓度反演的影响。实验中实地采集不同PM2.5浓度的样气,再分别与标准待测气体混合,最终通过对透射光光谱变化和待测气体浓度反演数据的比较,定量分析PM2.5浓度对系统的影响。实验中选用甲醛和苯作为待测气体,分别配制了六种浓度的待测气体,对6个雾霾浓度等级（No.1-No.6）分别进行了测试。实验结果显示,当PM2.5浓度增大时,系统光能吸收率降低。当PM2.5浓度等级小于No.3时,衰减变化相对缓慢,而大于No.3后衰减效果明显增强。当PM2.5浓度小于150 μg·m-3时,测试精度优于90%;当PM2.5浓度超过150 μg·m-3时,对VOC浓度反演的影响变强,当达到350 μg·m-3时,测试误差将近30%。由此可见,PM2.5浓度对弹光调制系统的气体浓度检测具有显著影响。

Research on the Influence of Haze for Detection System Based on Elastic Light Modulator

In recent years, haze phenomenon is becoming more and more serious in China. It not only harms people’s health and air traffic caused by security risks, but also affects a lot of optics equipment used outdoor. In order to quantitatively analyze the effect of different haze levels on the performance of the trace gas concentration detection system based on the elastic light modulator, the test system was designed. The effect of different PM2.5 concentration sample gas on the inversion of equivalent VOC gas concentration was quantitatively analyzed. In the experiment, different concentrations of PM2.5 were collected in the field, and then mixed with the standard gas to be prepared. Finally, the comparison of the transmitted light spectrum and the measured gas concentration inversion data was made. The effect of PM2.5 concentration on the system was quantitatively analyzed. In the experiment, formaldehyde and benzene were used as the gas to be measured. Six kinds of concentrations of the gas to be measured were prepared, and 6 haze concentration levels (from No. 1 to No. 6) were tested. The experimental results showed that when the PM2.5 concentration increases, the system light energy absorption rate is significantly reduced. When the PM2.5 concentration level is less than No.3, the attenuation change is relatively slower, and when it is greater than No.3, the attenuation effect is enhanced. When the PM2.5 concentration is less than 150 g·m-3, the test accuracy is better than 90%; When the concentration of PM2.5 exceeds 150 g·m-3, the effect of inversion of VOC concentration becomes stronger. When 350 g·m-3 is reached, the test error is nearly 30%. It can be seen that PM2.5 concentration has a significant effect on the gas concentration detection of the optical modulation system.