【作者】 张景茹；

【导师】 李志全；

【作者基本信息】 燕山大学 ， 检测技术与自动化装置， 2010， 硕士

【摘要】 矿山开采,机械制造以及冶炼过程中所排放的易燃易爆、有毒、有害气体严重影响了人类的健康和生存环境。因此,对这些气体进行实时有效的监测,是人们健康生活的基本保障。光纤环形腔衰荡光谱技术是在光纤通信和光纤传感技术的基础上发展起来的吸收光谱技术,由于这种技术具有较高的测量灵敏度,现已被广泛应用于痕量气体浓度测量领域。痕量气体浓度测量需要泵浦光源具有较高的功率密度,在追求高性能价格比的趋势下,本文对硅基拉曼激光器系统进行了研究设计,并将其应用到气体浓度测量领域。主要内容包括:首先,分析了光纤环形腔衰荡光谱技术的气体浓度传感原理,并建立了气体浓度测量的数学模型,同时分析讨论了影响测量精度的因素。介绍了硅基拉曼激光器的工作原理-受激拉曼散射效应,并进行了理论研究。其次,基于光纤环形腔衰荡光谱技术建立气体浓度测量系统,并重点研究设计了硅基拉曼激光器系统,对两个系统中的关键器件的性能和工作原理进行了分析,并建立了影响激光器性能的载流子寿命理论模型。采用提升小波变换对实验数据进行消噪处理,并对提升小波变换方法的消噪效果进行了仿真研究。最后,通过实验对所设计的硅基拉曼激光器的性能进行了分析。选用甲烷气体作为待测气体,对所设计的气体浓度测量系统进行了验证,并通过对比实验验证了提升小波变换方法对提高系统测量精度的作用。并实验测量了甲烷在不同浓度下的对数衰荡曲线以及衰荡时间与气体浓度的关系。更多还原

【Abstract】 The poisonous, harmful ,combustible and explosive gases produced in the process of mine mining, mechanical manufacturing and melting , affected the human health and survival environment seriously. So it is the basic guarantee of the human safety and healthy lives to monitor these gases effectively in time. Fiber loop ring-down spectral technology is based on the fiber communication and fiber sensor technology, because of the high sensitivity, and is widely used to measure the trace gases. Due to the high power density needed for the pump source to measure the trace gases, with the trend to pursue the high performance price ratio, I make a research on the Si-based Raman laser, and apply it to measure the gas concentration. The major content includes:Firstly, the gas concentration measurement principle of fiber loop cavity ring-down spectroscopy is analyzed, and the corresponding mathematical model is established. At the same time, the factor that influences the concentration precision is discussed. The stimulated Raman scattering which is the principle of Raman laser is introduced, and is investigated theoretically.Secondly, the gas concentration measurement system based on fiber loop cavity ring-down spectral technology is introduced and the Si-based Raman laser system is mainly investigated. Then the performance and principle of the key cells of the system are analyzed, and the carrier lifetime that affects the output performance of Raman laser is analyzed theoretically. At last, the lifting wavelet transform is adopted to denoise the experimental data, and the performance of the lifting wavelet transform to denoise is simulated.Finally, the performance of the Si-based Raman laser is analyzed experimentally. The system chooses the methane as the detected gas, and is demonstrated experimentally. The lifting wavelet transform to improve the measurement precision is demonstrated by the compared experiment. The absorption performance of methane and the relationship between the ring-down time and gas concentration are analyzed.更多还原