基于TDLAS的光源驱动及信号检测技术研究

发布时间：2018-05-16 05:04

本文选题：TDLAS技术 + 光源驱动　；参考：《电子科技大学》2015年硕士论文

【摘要】：当前空气污染问题受到了人们的空前关注,人们迫切需要寻求高性能的气体检测手段对污染气体进行高精度高稳定性检测。其中,可调谐激光吸收光谱技术(TDLAS)由于探测灵敏度高、探测范围广、响应时间短,很适合对较大范围的场地进行实时监测,并且可以避免光谱交叉干扰的影响等优点在气体检测领域受到了青睐。本文首先选择了以TDLAS技术为核心并结合波长调制谐波检测技术的气体检测的方案。从吸收光谱学原理入手,介绍了气体吸收谱线的特征,并对本课题所需要测量的甲烷气体的吸收谱线进行了选择;然后着重分析了可调谐二极管激光吸收光谱学技术的原理,介绍了本系统中对甲烷气体进行探测的实现方案。其次,选择了DFB激光器作为系统光源,设计了系统光源的驱动模块,包括电流源模块和温度控制模块。其中,电流源模块采用压控恒流源方案,并结合负反馈原理和PID算法实现对驱动电流的稳定控制;对电流源模块进行了硬件设计,制作了电流源模块的电路板,还进行了电流源模块的软件控制设计。选择了专业的温控芯片LTC1923来实现对激光器的温度控制,并以LTC1923芯片为核心设计了温控模块的硬件电路;并对温控模块进行了软件控制设计。再次,在信号检测部分选用了高性能的InGaAs光电探测器对光信号进行光电转换,设计了相应电路对信号进行处理。其中,前置放大电路对微弱电流信号进行放大,滤波电路用以对信号进行去噪处理,结合相关检测原理设计了以AD630芯片为核心的锁相放大器,用以提取待测气体的二次谐波信号。最后,对所设计的光源驱动模块的性能进行了测试,分析了驱动电流和工作温度对激光器的输出特性的影响;对所设计的光电放大模块和锁相放大器进行了测试。并对这些模块的性能缺陷做了分析,提出了改进措施。
[Abstract]:At present, people pay more and more attention to the problem of air pollution, and it is urgent to seek high performance gas detection methods for high precision and high stability detection. Due to its high detection sensitivity, wide detection range and short response time, tunable laser absorption spectroscopy (TDLAS) is suitable for real-time monitoring of a wide range of sites. And it can avoid the influence of spectral cross-interference and so on in the field of gas detection. In this paper, the scheme of gas detection based on TDLAS technology and wavelength modulation harmonic detection technique is first selected. Based on the principle of absorption spectrum, the characteristics of gas absorption spectrum line are introduced, and the absorption spectrum line of methane gas is selected, and the principle of tunable diode laser absorption spectroscopy technique is analyzed emphatically. The scheme of methane gas detection in this system is introduced. Secondly, the DFB laser is selected as the system light source, and the driving module of the system light source is designed, including the current source module and the temperature control module. The current source module adopts voltage-controlled constant-current source scheme, combines the principle of negative feedback and PID algorithm to realize the stable control of the driving current, designs the hardware of the current source module, and makes the circuit board of the current source module. The software control design of the current source module is also carried out. A special temperature control chip LTC1923 is selected to realize the temperature control of the laser. The hardware circuit of the temperature control module is designed based on the LTC1923 chip, and the software control design of the temperature control module is carried out. Thirdly, in the signal detection part, the high performance InGaAs photodetector is used to convert the light signal, and the corresponding circuit is designed to process the signal. Among them, the preamplifier circuit amplifies the weak current signal, the filter circuit is used to Denoise the signal, and a phase-locked amplifier based on AD630 chip is designed based on the principle of correlation detection. It is used to extract the second harmonic signal of the gas to be measured. Finally, the performance of the designed light source driving module is tested, the effects of driving current and operating temperature on the output characteristics of the laser are analyzed, and the designed optoelectronic amplifier and phase-locked amplifier are tested. The performance defects of these modules are analyzed and the improvement measures are put forward.
【学位授予单位】：电子科技大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：X831

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