基于光纤收发一体的紫外增强差分吸收光谱系统的研究

Research on a UV-enhanced Differential Optical Spectroscopy system with combined transmitting-receiving fibers

针对现有差分吸收光谱(DOAS)大气监测系统紫外光强不足,信噪比不高等问题,研制了基于光纤收发一体的紫外增强DOAS大气监测系统。该系统在光纤收发一体结构的基础上进行了改进优化,并采用紫外增强氙灯作为系统光源,改进了系统光源耦合设计,用角反射镜阵列替代单个角反射镜。对优化的DOAS系统进行了紫外光强外场测试,结果显示,单光程为135 m下光谱仪积分时间仅为15 ms,接收光强能达到最大量程的80%以上。采用SO2、NO2标气对系统进行了标定实验,并利用系统对大气污染物SO2、NO2进行了连续监测,结果表明系统性能先进,完全满足雾霾等能见度低的天气下大气在线监测要求。

In view of the problem of insufficient UV intensity and SNR of existing Differential Optical Absorption Spec- troscopy（DOAS） atmospheric monitoring system, a UV-enhanced DOAS atmospheric monitoring system with combined transmitting-receiving fibers was developed. The system was optimized based on the structure of combined transmitting- receiving fibers. In addition, UV-enhanced xenon lamp was used as light source of the system to improve the design of light coupling, and the retro reflector array was used instead of a single rctro reflector. The UV intensity of the opti- mized DOAS system in the open air was tested, and the results showed that once the integration time of spectrometer was only 15ms, the received light intensity reached more than 80% of the maximum. SO2, NO2 standard gas was used to conduct calibration experiments of the system and using the system to continuously monitor the atmospheric pollutants SO2 , NO2. The results showed that the performance of the system was advanced, and it could fully meet the require- ment of on-line monitoring of atmospheric quality on low visibility weather such as fog.