【作者】 郭旋；

【导师】 王智；

【作者基本信息】 北京交通大学 ， 光学， 2010， 硕士

【摘要】 近年来,随着煤矿业、环境监测、石油化工等行业对甲烷气体浓度检测的重视,可靠、实时、快速越来成为甲烷气体检测的追求方向。光纤传感器其抗电磁干扰力强、灵敏度高、重量轻、易集成等特点,倍受国内外学者关注。本文所设计的光纤传感系统,是基于气体光谱吸收特性的单环光纤系统,气室置于单环中,采用耦合器分光,光脉冲多次经单环形成光功率损耗,并分别对初始状态和气体吸收状态下的光脉冲波形进行了分析拟合处理,通过计算出衰荡时间来确定气体吸收损耗,从而测算出气体浓度。本文以此思想为指导,对光纤衰荡环作了详细的理论分析,得出测量气体浓度的理论依据,并对系统各部分进行测试,搭建了光纤网络系统。还根据实验需求,设计制作了光信号源的驱动电路板,实现了直流偏置、交流调制、温控、显示功能,给光纤传感器提供了可靠的光脉冲信号。通过这种方法测得的气体浓度,与标准浓度基本吻合。更多还原

【Abstract】 In recent years, as mining industry, environment monitoring and petrochemical industry being more concerned with methane gas detection, detecting reliably, instantly and rapidly must be the main direction and objection. Optical fiber sensor, due to its electromagnetic immunity, high sensitivity, light weight and easy integration has grasped more attention.Placing gas cell in single-loop optical fiber, an optical fiber sensing system is designed which based on spectrum absorption principle of methane gas. Light pulse generated by DFBLD split up into two parts by coupler, the optical power of one part of which pass through the single-loop optical fiber several times will be attenuated. By fitting the curve of the optical pulse power in the original state and in the gas absorption state, ring-down time is figured out to gain gas absorption loss and gas concentration.On the basis of the principle, a detailed analysis of the fiber ring-down theory is made, by which the gas concentration is figured out, the parts of the system are tested, and structural system is built. Taking account to the system need, driver circuit of DFBLD is designed to achieve the direct current driving, alternating current driving and temperature monitoring, so a reliable light pulse signal are attained. The gas concentration gained by this way is basically coincident with the standards.更多还原