两路反馈外腔结构自混合干涉信号处理方法研究

发布时间：2018-06-02 14:35

本文选题：自混合干涉 + 两路反馈　；参考：《南京信息工程大学》2017年硕士论文

【摘要】：光反馈自混合干涉效应(OFSMI)是指激光器输出光被外部物体反射或者散射后,部分光反馈回激光器谐振腔内,并与腔内光产生混合,导致激光器输出功率和频率发生改变,形成自混合干涉效应。自混合干涉与传统的双光束干涉相似,但在理论上又与传统的干涉不同,且二者的特性也有所差异。光反馈自混合干涉测量较传统的干涉测量具有结构简单、易准直、光路紧凑和成本低等优点。目前,自混合干涉现象的研究不断深入。但对基于特殊外腔结构激光自混合干涉理论的研究还不够充分。因此,本文着重研究外腔结构为两路反馈的激光自混合干涉系统。两路反馈外腔结构自混合干涉的每路反馈都会携带一个物体的运动信息,能够实现对两个待测目标的同时测量,且其类似于多重外腔结构自混合干涉。由于目前对该特殊结构的自混合干涉模型只是进行了理论分析'与实验观察,还没有对自混合干涉信号处理的方法进行充分的研究。因此,文中通过对两路反馈外腔结构自混合干涉模型的分析,在弱反馈水平下对自混合干涉信号的处理方法进行了深入的研究。首先利用希尔伯特变换(Hilbert)原理对两路反馈自混合干涉信号的相位进行重构;然后对重构的信号相位做FFT变换得到信号相位的频谱,再通过滤波分别得到两路信号频谱;最后再对两路信号频谱做IFFT变换恢复出两路信号时域的位移波形。同时为了减少自混合干涉信号中噪声的干扰,提高位移测量的精度,本文提出了一种基于小波软阂值和集合经验模态分解(EEMD)相结合的信号预处理方法,通过模拟仿真分析及对实验采集信号的去噪处理,验证了该方法的有效性和适用性。另外,针对外腔结构为单路反馈和两路反馈的激光自混合干涉系统进行了相应实验平台的设计。主要对DS102、PZT的使用及信号的采集方法做了简要介绍,对在实验过程中出现的问题进行简单说明,并提出相应的解决方法。
[Abstract]:The light feedback self mixing interference effect (OFSMI) means that the output light of a laser is reflected or scattered by an external object, and a partial light is fed back into the resonator of the laser and is mixed with the cavity light, resulting in a change in the output power and frequency of the laser and the formation of a self mixing interference effect. It is different from the traditional interference in theory, and the characteristics of the two are also different. The optical feedback self mixing interferometry has the advantages of simple structure, easy alignment, compact optical path and low cost. At present, the study of self mixing interference is going deep. The study is not sufficient. Therefore, this paper focuses on the laser self mixing interference system with two feedback in the outer cavity structure. The feedback of the two channel feedback external cavity structure self mixing interference will carry the motion information of an object, and can realize the simultaneous measurement of two targets to be measured, and it is similar to the multiple external cavity structure self mixing interference. Because of the theoretical analysis and experimental observation of the self mixing interference model of the special structure, there is no sufficient research on the method of self mixing interference signal processing. Therefore, the self mixing interference signal is processed at the weak feedback level by the analysis of the self mixing interference model of the two feedback external cavity structure. The method is studied in depth. First, the phase of two feedback self mixing interference signals is reconstructed by using the Hilbert transform (Hilbert) principle. Then the phase spectrum of the signal phase is obtained by FFT transformation of the reconstructed signal phase, and then the two channel signal frequency spectrum is obtained by filtering. Finally, the two channel signal spectrum is regenerated by IFFT transform. In order to reduce the interference of the noise in the interference signal of the self mixing interference signal and improve the precision of the displacement measurement, a signal preprocessing method based on the combination of the wavelet soft threshold and the collective empirical mode decomposition (EEMD) is proposed, and the simulation analysis and the denoising processing of the experimental acquisition signal are performed. The validity and applicability of the method are proved. In addition, the design of the corresponding experimental platform is designed for the laser self mixing interference system with single channel feedback and two way feedback. The use of DS102, PZT and the method of signal acquisition are briefly introduced, and the problems in the experimental course are briefly explained and the phase is put forward. The solution should be solved.
【学位授予单位】：南京信息工程大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TN24;TN911.7

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