摘要
氨气是主要恶臭物质之一,为了实现工业环境污染源中氨气排放的连续监测,研制了中红外激光气体传感器,与传统近红外氨气传感器受干扰气体影响较大不同的是,该传感器采用中红外分布反馈结构的带间级联激光器(distributed feedback inter-band cascade laser,DFB-ICL)为光源,工作波长在3μm附近,避免了水和CO_2干扰气体的影响,同时以空芯光波导(芯径1 mm、长度5 m)做气体池,采用自制多通道数字锁相放大器,同时解调1f和2f谐波信号,实现免校准测量,获得了传感器的梯度实验结果,线性度高达0.99917,不确定度高达0.9%,Allan方差评价结果显示其稳定性非常出色,在最佳积分时间167s时,本传感器的检测限低至9.7 ppb。
Ammonia is one of the main odors. A mid-infrared laser based gas sensor was developed for continuous monitoring of the ammonia in pollution emissions in the industrial environment. Different from the traditionalnear-infrared ammonia sensor, a mid-infared distributed feedback inter-band cascade laser（DFB-ICL） was used as light source, tuned at the center of 3 μm,which could qualify the sensor to avoid from the interference of water vapor as well as carbon dioxide. A hollow silica waveguide was used for gas cell, and the core diameter is 1 mm, the length is 5 m. A home-made multi-channel digital lock-in amplifier was adopted to demodulate 1 f/2 f harmonics simultaneously so as to realize calibration-free measurement. Concentration gradient results show that this sensor has a linearity as high as 0.99917 as well as an uncertainty of 0.9%.Based on the Allan variance method, it can be clearly seen that the sensor shows a quite excellent stability performance with a detection limit as low as 9.7 ppb at the optimum integration time of 167 s.
出处
《大气与环境光学学报》
CAS
CSCD
2017年第6期411-418,共8页
Journal of Atmospheric and Environmental Optics
基金
国家重大科学仪器设备开发专项
2012YQ06016501~~
关键词
分布反馈级间级联激光器
空心光波导
氨气检测
可调谐激光吸收光谱
波长调制光谱
distributed feedback inter-band cascade laser
hollow silica waveguide
ammonia detection
tunable laser absorption spectroscopy
wavelength modulation spectroscopy
