【作者】 田卡丽；

【导师】 王立新；

【作者基本信息】 武汉理工大学 ， 通信与信息系统， 2008， 硕士

【摘要】 一氧化碳(CO)是一种有毒的可燃可爆性气体,它给工业安全生产带来巨大危害。为了实现对CO的检测,装设可燃气体检测器,及时发现事故隐患、尽早采取补救措施是非常必要的。采用红外技术检测CO不但克服了以往检测方法的不足,而且还具有选择性好、连续分析、响应速度快等优点,更能适用于矿井气体的检测环境,因此将红外技术应用于矿井CO的检测具有重要的意义和良好的应用前景。本论文利用气体近红外光谱吸收原理,设计了一种光纤气体传感器。以一氧化碳为目标气体,确定了气体的吸收谱线,找出了适合普通石英光纤进行较长距离低损耗传输的光谱特性。采用分布反馈式半导体激光器(DFB LD)做光源,通过光源调制实现气体浓度的谐波检测。利用二次谐波与一次谐波的比值来消除由光源不稳定等因素所引起的误差。本论文所做的主要工作包括:1.光谱吸收式光纤气体传感器检测原理的研究。分析了正弦波和三角波调制的谐波检测方法,并对两种方法进行了比较。同时简要介绍了光源调制技术。2.确定CO气体的吸收峰,并在选择好波长和测量方法的基础上,选择DFBLD作为光源,InGaAs PIN光电二极管作为探测器。3.在理论分析的基础上,设计出基于DFB LD光源的光纤气体传感器系统。在电路设计上采用锁相放大器来获取微弱信号,最大程度的抑制噪声,提高系统的信噪比。4.以CO为目标气体,初步得到气体浓度的检测曲线,验证了检测方法,为后续研究提供了参考数据。5.DFB LD光源的外壳温度和内核温度的控制非常重要,这将直接影响光源的输出中心波长。改进了温控模块的设计。更多还原

【Abstract】 Carbon Monoxide is a poisonous gas which is flammable and explosive, it brings a great damage to industry safety production. In order to realize the CO detection, equip a flammable gas sensor, find the danger of accident immediately, take a saving measurement is very essential. We use infrared technique to detect CO, not only overcome the shortage of usual detect measurement, but also have many virtues such as good selectivity, continuous analysis and quick response, it is more suitable to the mine environment, so using the infrared technique to the CO detection has an important meaning and a good application foreground.In this thesis, we use the spectrum absorption method, design a kind of fiber optic sensor. We use the CO as the experiment gas, confirm the spectral absorption, and find out the spectra characteristics which are fit for low-loss transmission window of optic fiber. Distributed Feedback laser diode (DFB LD) is used as a light source and light source modulation harmonic measurement is presented in this paper. The ratio of the fundamental and second harmonic signal can be used as output for eliminating the interference owing to the light power changing.The main works of this thesis include:1. Study on spectrum absorption measurement principle of optical fiber gas sensor. Analysis sine wave and triangle wave modulation harmonic measurement and compare the two ways. At last, simply introduce the technology of source modulate.2. Select CO absorption apex, choose DFB LD as the light source, InGaAs PIN photodiode as the detector, based on the wavelength and measuring method that are selected.3. According to the theoretical analysis, we design a optical fiber sensor system based on DFB LD. The feeble signal is obtained by phase locked amplifier. The noise will be restrained in maximum degree, and the ratio of signal to noise will be raised.4. Using the CO as the sample gas, do some experiments and get the concentration measurement curves, valuate the system, and supply some data for the following research.5. Improve on controlling the light sour’s working temperature, because the changing of DFB LD surface and kernel temperatures will affect the light source’s centre wavelength.更多还原