【作者】 朱凡；

【导师】 谭久彬；

【作者基本信息】 哈尔滨工业大学 ， 仪器科学与技术， 2013， 博士

【摘要】 激光自准直技术是精密小角度测量的重要手段，具有测量分辨力高、测量距离远、非接触、使用方便等优点，在精密装备制造、光学元器件加工与检测、大型结构件装配、航空航天设备的瞄准与标校以及科学研究等领域具有重要应用。激光自准直由于激光发光机理以及光束传输路径中空气介质不稳定性导致的激光光束方向漂移而普遍存在测量稳定性较差的问题。激光光束的方向漂移是制约提高激光自准直小角度测量稳定性的主要障碍。本课题“基于共光路光束漂移测量与同步补偿的激光自准直技术”，在对自准直几何光学模型研究的基础上，分析激光自准直中激光光束漂移对自准直的影响机理，寻找从根源上减小激光自准直漂移的途径，并提出激光自准直中共光路光束漂移测量方法，结合高频响与高灵敏度光束方向偏转技术对光束漂移进行同步补偿，达到提高激光自准直小角度测量稳定性的目的。论文主要研究内容为：针对传统自准直模型参数过于简化而无法从理论上对自准直系统的影响因素进行有效分析的问题，建立了基于光线追迹法的自准直几何光学模型，能够完整地阐述自准直中各参数之间的关系。利用该模型对自准直系统中反射镜二维角度耦合、物面与像面离焦、以及照明光源的角漂移量对自准直小角度测量的影响进行仿真分析，结果表明，当物点位于准直物镜焦面并且距离光轴±5mm范围内时，在±2000″范围内反射镜二维角度耦合的影响量最大为0.7170″；物面与像面在±2mm范围内离焦时，在±2000″内影响量最大为4.3540″；在物面与像面离焦以及准直物镜孔径面光强分布不均匀的情况下，照明光源的角漂移量在±10″内对自准直小角度测量的影响量可以达到0.0182″。在此基础上进一步分析激光自准直中分辨力的影响因素，研究采用长焦距准直物镜和光学放大法提高自准直小角度测量的分辨力。针对激光基准精密小角度测量中激光光束的漂移与被测角度耦合而难以将二者有效分离的问题，提出激光自准直中基于组合靶标以及基于平面镜参考靶标的共光路光束漂移测量方法，方法中利用组合靶标或平面镜参考靶标，在自准直过程中产生一束参考光束，参考光束与测量光束来源于同一光源并且共光路传输，因而二者具有一致的角漂移量；由于组合靶标或平面镜参考靶标的固有特性，参考光束对组合靶标或平面镜参考靶标的角度偏转不敏感，因此可以利用参考光束精确获取测量光束的角漂移量，进而对其进行同步补偿，提高激光自准直小角度测量的稳定性。针对激光光束漂移量闭环控制中光束方向偏转装置的高频率响应与高角位移灵敏度相兼顾的问题，提出两种基于柔性铰链结构的光束方向偏转方法，通过建立其动力学模型，利用拉格朗日方程分析其固有频率随结构参数的变化关系，为优化其结构参数、在高角位移灵敏度的情况下提高固有频率提供理论依据；并且提出一种基于反射镜平动的光束方向偏转方法，通过压电陶瓷驱动反射镜平动实现光束的角度偏转，无机械摩擦与传动损耗，运动惯量小，因而具有非常高的角位移灵敏度与频率响应特性。实验结果表明，基于柔性铰链结构设计的两种光束方向偏转方法的角位移分辨力均可以达到0.003″，基于反射镜平动的光束方向偏转方法角位移分辨力优于0.002″，频率响应特性可以达到2000Hz以上。最后，对研制的基于共光路光束漂移测量与同步补偿的激光自准直实验装置及其各主要组成单元的性能进行测试，包括光学放大法的有效性测试、光电检测电路的分辨力测试、参考光束与测量光束角漂移量的一致性测试、光束方向偏转装置的性能测试，在此基础上对所组成的激光自准直系统的有效分辨力和稳定性进行测试。实验结果表明，其有效分辨力达到0.0003″，2小时稳定性最高可以达到0.0026″，在高的有效分辨力下实现了高测量稳定性。更多还原

【Abstract】 Laser autocollimation is an important method for precision small anglemeasurement with high angle resolution, long measurement distance, andcharacteristics of noncontact, convenient to use, etc. It is widely used inmanufacture and testing of precision equipment, processing and testing of optics,assembling and testing of large structures, aiming and calibration of aerospaceequipment, and scientific research, etc. However, it is commonly experienced thatlaser beam drift due to laser generation mechanism and instability of beamtransmission medium cause a poor measurement stability in laser autocollimation.Laser beam drift is the main obstacle of improving the measurmement stability oflaser autocollimation.In this dissertation of “Laser autocollimation technology based oncommon-path beam drift measurement and synchronous compensation”, the modelof autocollimation in Gaussion optics is researched and used to analyze the effect oflaser beam drift on laser autocollimation to find methods to eliminate the drift oflaser autocollimation foundamentally. Common-path beam drift measurementmethod in laser autocollimation is also proposed. The beam drift is synchronouslycompensated by beam steering technology with high frequency response and highsensitivity, to achieve high stability of laser autocollimation small anglemeasurement. The main researches of this dissertation are described as followings:An autocollimation model based on Gaussion-optics is established by usingray-tracing method to solve the problem that the conventional autocollimationmodel can not be used to analyze the affects of autocollimation system effectively.The established model describes the relationship of all the parameters ofautocollimation system. Simulations have been done to analyze the effects oftwo-dimensional tilt-angle couple of the mirror, defocus of object and image planes,and angular drift of illuminating light source. The simulation results show that themaximum deviation caused by two-dimensional tilt-angle couple of the mirror isabout0.7170″in a measurement range of±2000″when an object point locates at therange of±5mm relative to the optical axis. The maximum diviation is about4.3540″in a measurement range of±2000″when object and image planes defocus in a rangeof±2mm. The drift of autocollimation small angle measurement can be0.0182″when the angular drift of illuminating light source ranges in±10″. The influencefactors of the resolution of laser autocollimation are also analyzed. The collimatinglens with long focal length and optical amplification method are studied to improvethe resolution of autocollimation small angle measurement. Common-path beam drift measurement methods based on combination reflectorand reference mirror reflector in laser autocollimation are proposed to solve theproblem that laser beam drift and the small angle being measured are alwayscoupled and hard to be separated in laser datum based small angle measurement.The combination reflector and reference mirror reflector are used to generate areference beam in autocollimation. The reference and measurement beams arederived from the same illuminating light source and transmitted on common-path, sothey have the same angular drift. In addition, the reference beam is insensitive to theangular rotation of the reflectors due to their unique characteristics. So the referencebeam can be used to accurately obtain the angular drift of measurement beam forsynchronous compensation to improve the small angle measurement stability oflaser autocollimation.Two beam steering methods based on flexible hinge are proposed to solve thecollision of high frequency response and high angular sensitivity of beam steeringmechanism in close-loop control of laser beam drift. The dynamical models of thetwo methods are established to analyze the variations of natural frequencies withtheir structure parameters. The models provide theoretical optimization of thestructure parameters to increase natural frequencies along with high angularsensitivities. Another transmission mirror based beam steering method is alsoproposed. The beam steering is realized by the transmission of a mirror which isactuated by PZT actuators. There is no mechanical friction or motion transmissionloss, so the method has a very high angular sensitivity and high frequency response.Experimental results show that angular sensitivity of the two beam steering methodsbased on flexible hinge can be0.003″and the transmission mirror based method canbe better than0.002″. All the frequency responses of the three methods can be up to2000Hz.An experimental laser autocollimation system based on common-path beamdrift measurement and synchronous compensation has been set up. The performanceof constitution units has been tested, including effectiveness of optical amplificationmethod, resolution of the photoelectrical detection units, consistency of the drifts ofreference and measurement beams, performance of the beam steering mechanisms,the effective resolution and measurement stability of the autocollimation system.Experimental results show that the effective resolution is0.0003″, and the2-hourstability can reach up to0.0026″, which demonstrates that a high stability is realizedon the base of high effective resolution.更多还原