基于量子级联激光器红外CO检测系统的关键问题研究

发布时间：2018-03-18 10:06

  本文选题：量子级联激光器　切入点：锁相放大器　出处：《吉林大学》2017年硕士论文　论文类型：学位论文

【摘要】：在开采难度大的地区进行矿井开采作业极易造成煤气层泄漏和煤尘自燃等重大安全事故。因此研制出可实时监控矿井下CO气体浓度的传感器具有重大的安全意义。目前矿用气体检测仪主要的研究发展方向是应用红外光谱吸收技术对有毒气体进行识别与浓度测量。其中选用单色性好、准直度的量子级联激光器(QCL)作为红外检测系统的光源与其他红外光谱吸收技术相比,具有更强的分子鉴别力和更高的检测精度。因此本课题具有十分重要的研究意义。基于脉冲式中红外QCL的气体检测系统中主要存在两大关键问题:一、应用脉冲锁相放大技术精准提取窄脉冲传感信号;二、有效调控气体吸收池温度、压强等参数,实现最佳检测过程。本论文研究基于以上关键问题展开。首先设计并实现一种窄脉冲锁相放大器,主要由窄带滤波电路、乘法器电路、低通滤波电路等构成。并对其开展了详细的功能验证实验,实验结果表明该窄脉冲锁相放大器具有良好的频率响应(中心频率5k Hz)、较低的通频带宽度(带宽80Hz)、较高的线性度(拟合优度98.043%)。其次对红外吸收池的多种参数进行控制,包括温度控制单元和流量控制单元两部分。利用Fuzzy-PID复合控制理论对不锈钢密闭腔体开展温度控制实验,实验曲线表明该温控系统具有较快的响应速度(响应时间7mins)及较低的稳态误差(控制精度±0.2℃)。并利用质量流量计对模拟气室的流量进行调控,多次控制结果证明,该流量控制单元可实现误差在满程的5%左右的控制功能,且具有良好的重复性。最后通过实验室完整的CO检测平台进行了CO气体标定实验,测试结果证实了在红外吸收池温度、流量等参数选定时,所研制的锁相放大器可以有效地检测出红外吸收池通入的CO气体浓度,且系统检测精度较高、稳定性较好。
[Abstract]:It is easy to cause gas leakage and coal dust spontaneous combustion and other major safety accidents in mining operation in areas where mining is difficult. Therefore, it is of great safety significance to develop a sensor that can monitor CO concentration under mine in real time. At present, the main research direction of mine gas detector is to use infrared spectrum absorption technology to identify and measure the concentration of toxic gas. As the light source of infrared detection system, the collimated quantum cascade laser (QCL) is compared with other infrared absorption techniques. Therefore, this subject has very important research significance. There are two key problems in the gas detection system based on pulse mid-infrared QCL: first, The pulse phase-locked amplification technique is used to accurately extract the narrow pulse sensing signal. Second, the parameters such as temperature and pressure of the gas absorption cell are effectively controlled. This thesis is based on the above key problems. Firstly, a narrow pulse phase-locked amplifier is designed and implemented, which consists of narrow band filter circuit and multiplier circuit. The low pass filter circuit and so on, and carried out the detailed function verification experiment to it, The experimental results show that the narrow-pulse phase-locked amplifier has a good frequency response (center frequency 5k Hz), low bandwidth (bandwidth 80 Hz), high linearity (good fit degree 98.043). Secondly, various parameters of infrared absorption cell are controlled. It includes two parts: temperature control unit and flow control unit. Using Fuzzy-PID compound control theory, the temperature control experiment of stainless steel airtight chamber is carried out. The experimental results show that the temperature control system has fast response speed (response time 7 mins) and low steady-state error (control accuracy 卤0.2 鈩，

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