开放式激光检测中自动增益调节模块的研究

利用可调谐二极管吸收光谱技术结合开放式长光程技术对大气中痕量气体进行浓度监测的过程中,受到昼夜光强变化和大气能见度变化等因素的影响,信号在采集时变化幅度比较大,放大后的信号幅值有可能超出A/D转换的量程.设计了一种信号自动增益调节模块,应用在激光检测系统的信号放大处理过程中,并在福建泉港石化园区内对大气开放环境中的氨气浓度进行了连续监测.园区监测结果表明园区氨气浓度具有日变化周期:早晚浓度低,中午浓度高,主要来源于燃料燃烧和工业排放.解决了信号采集过程中信号幅度大幅变化的问题,验证了增益自动调节模块的功能,实现了稳定连续的痕量气体检测.

Automatic Gain Adjustment Modular in Open Path Detection Based on Laser Technology

During the process of monitoring trace gases of the atmosphere based on tunable diode laser absorption spectroscopy and long open path technology,signal amplitude changes relatively large due to the diurnal light intensity variation,atmospheric visibility changes and other factors,and the signal amplitude may exceed the range of A/D conversion after amplification.Automatic gain modular was designed to amplify signals in the laser detection system,and monitor ammonia concentration continuously of Quangang Petrochemical Parks in Fujian Province.The monitoring result shows that the ammonia concentration of the Petrochemical Park has a diurnal variation cycle:the concentration is low in the morning and night,and high in the noon,ammonia mainly comes from fuel combustion and industrial emissions.The problem of large signal fluctuation in the signal acquisition process was solved.The function of the automatic gain modular were verified and the stable and continuous trace gases detection was achieved.