【作者】 杨波；

【导师】 吕亮；

【作者基本信息】 安徽大学 ， 光学工程， 2015， 硕士

【摘要】 激光自混合干涉效应是指激光器的输出光被外界物体部分反射或散射后,重新反馈回激光器的谐振腔内,这部分携带外部物体信息的反馈光与腔内光发生干涉,调制激光器的输出特性,从而可以实现对目标物的物理量的测量。与传统干涉系统相比,自混合干涉系统仅有一个干涉通道,结构简单、紧凑,易准直,灵敏度高,目前已广泛应用于工业测量、科学研究、国防军事等众多领域。本文结合激光自混合干涉效应的原理以及直角棱镜的自反馈特性,提出并实现了一种能够满足高分辨率、宽范围的角度测量系统,所研究的测角系统的测量分辨率可以达到0.55mrad,测量范围可以达到21.49mrad。同时本文还对不同待测物表面的散射特性以及光纤激光器中不同的尾端结构进行了讨论分析,为激光自混合系统的优化提供了理论指导和实验支持。本文所做的研究工作主要包括以下几个方面：1.提出了一种新型的基于自混合干涉技术的高分辨率、宽范围的角度测量系统,给出了不同波长的激光器作为光源时的基本理论分析与数值模拟结果。2.在理论分析的基础上成功设计并搭建了所研测角系统的实验装置,观察到了不同波长的激光器作为光源时的实验现象,同时给出了实验现象的分析结果,最后讨论分析了实验的误差来源,为下一步系统的优化和改进奠定了基础。3.对不同待测物表面的散射特性进行了相关研究。理论和实验结果表明,反射膜的信噪比和散射率大部分地大于其他的散射面,并且信噪比会随着散射角的增大而呈递减特性。4.对于作为反馈光收集结构的不同光纤尾端进行了相关研究。通过对比实验现象和理论结果可以得出,不同的光纤尾端有着不同的耦合效率,但却适用于不同的应用场合。本论文的主要创新点包括：1.搭建了一个新型的基于激光自混合干涉技术的微角度测量系统,利用直角棱镜入射光平行于出射光的特性,简化了调节光路的难度,从而有效克服了传统测角系统灵敏度低和测量范围受限的问题。2.该新型系统利用微片激光器作为光源时,能够在保证测量分辨率达到0.55mrad的同时获得18.90mrad的测量范围；利用氦氖激光器作为光源时的分辨率为0.61mrad,测量范围可以达到21.49mrad。3.在对不同待测物表面的散射特性的相关研究中,通过使用一个反射膜,并且选取一个合适的角度可以帮助我们消除散斑带来的影响,同时提高自混合信号的信噪比,为以后的系统优化提供了基础。4.在对作为反馈光收集结构的不同光纤尾端的相关理论分析中,可以利用.ABCD矩阵在近轴条件下计算出不同光纤尾端收集反馈光过程中的耦合效率。更多还原

【Abstract】 Laser self-mixing interference effect occurs when the light back-reflected or back-scattered from external object and reenters the laser cavity, the reflecting light then mixing with the light inside the cavity, causing the modulation of output characteristics. Then the measurement of the physical quantity of the target will be achieved. Compared with the traditional interference technique, self-mixing interference has just one interference channel, simple and compact structure, self-aligning, high sensitivity. So it has been employed widely in the field of industrial measurement, scientific research, national defense and so on. We put forward an angle measurement system which can be applicable to the occasion with high requisition of resolution and range based on the self-mixing interference effect and the characteristics of the right-angle prism. The measurement range of the angle measurement system can reach 21.49 mrad and the resolution can reach 0.55 mrad. In addition, we also studied the external objects scattering property and the fiber ring laser with different fiber-ends, which provide a theoretical guidance and experimental support for the optimization of the laser self-mixing interference system. The research work we have devoted to this paper mainly include the following aspects:1. Here we proposed a novel self-mixing angle measurement system with high resolution and wide range, and gave the basic theoretical analysis and numerical simulation results with different wavelength of laser source.2. According to the theoretical analysis, an experiment device was designed and built successfully. In addition, the experimental phenomena of lasers with different wavelength as the light source were observed, the analysis results of experimental phenomena and the relative angle error were given in the paper, which laid a foundation for the next step of the system optimization and improvement.3. The influence of different external objects scattering property on the self-mixing interference technology were analyzed and discussed. Theoretical and experimental results show that the scattering ratios and SNR of the reflective film are mostly bigger than the other scattering surfaces, and the mean SNR values of self-mixing signal demonstrate decline characteristic as the incident angle increases.4. We have performed related research on different fiber-ends as the light collection structure. It can be obtained that different fiber-ends have different coupling efficiency, different structures have different application advantages in measurements by comparing the experimental phenomenon and the theoretical results.The followings are the innovative points in this paper:1. We carried out a new small-angle measurement experiment based on the self-mixing interference. By using the characteristics of the right-angle prism that the incident light is parallel to the emergent light can overcome the issues of traditional method, such as low sensitivity and limited range.2. As a consequence, the measurement range and the resolution of MSL as light source in the angle measurement system can reach 18.90 mrad and 0.55 mrad, while the range and the resolution of He-Ne laser can up to 21.49 mrad and 0.61 mrad.3. In the study of the external objects scattering property, the SNR of the self-mixing signal can be enhanced by using a reflective film and choosing a suitable angle can help us eliminate the bad effect caused by speckle pattern partially, which provide a foundation for the optimization of the laser self-mixing interference system.4. In the theoretical part of the influence of different fiber-ends on the laser self-mixing signal, we use the ABCD matrix under paraxial approximation for the calculation of coupling efficiency inside the fiber ring laser with different fiber-ends.更多还原