【作者】 任淑艳；

【导师】 浦昭邦；

【作者基本信息】 哈尔滨工业大学 ， 仪器科学与技术， 2008， 博士

【摘要】 光学非接触式测量是当前三维测量领域的研究热点,对提高检测速度、降低损耗、增强检测手段的环境适应性具有重要意义。在各种非接触式测量方法中,锥光全息法以其测量范围大、精度高及环境适应能力强等特点更适合在线检测的应用,但该方法目前还没有得到广泛的应用,根本原因在于对该系统的研究还存在一定的局限性。本文在对国内外锥光全息系统的理论研究和制约其在线应用的各种因素进行分析的基础上,提出提高系统抗干扰能力和测量分辨力的新方法,并建立具有通用性和灵活性的模块化操作系统,完成锥光全息测量系统的非线性校准,开发适应性强、能够在多种工业生产中应用的在线检测系统,而且对提高非接触式测量的水平具有很大的实际意义。详细分析了总体方案和各组成子系统方案,设计出适用于距离测量和三维形状测量的锥光全息系统,并搭建实验平台进行参数校正及样机调试。同时,结合几何光学、晶体光学及偏振光学等理论,深入分析锥光全息系统的不足,并提出解决办法。研究基于相位的系统测量方法,相比于全息图的光强易受光源波动和噪声干扰的问题,从全息图的相位中更易精确地提取被测信息,而且能充分反应锥光束在晶体中的传播特性。在此分析的基础上,推导锥光全息系统基于相位的测量表达式,相应降低光源波动影响。研究图像噪声处理技术,针对图像的方向性特征,在分析现有方向滤波方法的基础上,提出了改进的平均曲率扩散滤波方法,加快了算法的速度。通过对晶体光学传输模型和条纹检测技术的研究,采用条纹整数频率与小数相位同时提取的区域条纹扫描方法,并将条纹频率的像素级确定方法和相位的亚像素定位方法相结合,省去了不必要的处理和计算,在满足测量精度的基础上加快了测量速度。为确保大量程的前提下系统仍具有较高的测量精度,研究了提高锥光全息系统测量分辨力的方法,采用加大晶体转角和加入光学透镜的相位差放大法,在提高系统检测精度的同时,也降低了系统的标定难度。研究系统的传输特性和非线性校准技术,进行增量式测量和相对相位测量的理论分析,使得锥光全息系统实现增量式相对相位测量,避免了系统在大量程内绝对零位的难于定位问题。并结合遗传算法优化特性参数,采用神经网络技术实现对增量式测量的非线性校准,降低系统的非线性误差,同时也避免了求取特性函数逆向模型的困难。对于影响系统测量的各种因素进行分析,通过软件补偿光学元件引起的系统误差,并对引起激光器波长漂移和单轴晶体折射率变化的温度因素采取了结合PID技术的自适应调节方法,降低了测量系统对于环境温度的要求,从而提高了锥光全息系统的环境适应能力。更多还原

【Abstract】 As a main subject in 3D measurement, Optical non-contact measurement can improve detection velocity, reduce loss and intensify adaptability to environment. Among all kinds of the optical non-contact measurement methods, Conoscopic Holography measurement is more suited to on-line detection because of its large measurement scope, high accuracy and adaptability to environment. But Conoscopic Holography measurement has not been applied in industry for its limitation on research theory. In this paper, theories about Conoscopic Holography method from foreign countries and factors restraining its on-line application have been analyzed, and new ways to improve antijamming ability and measurement resolution have been proposed. Modularization operation system with commonality and flexibility was built, and non-linear calibration for Conoscopic Holography system was performed. Research goal is developing strong adaptabilty and on-line detectin system in industry, which is important for optical non-contact measurement.After analysis on overall scheme and subsystem schemes, Conoscopic Holography measurement system adapted to measure distance and 3D shape was designed, and experiment flatform built was used to adjust parameters and debug prototype. At the same time, shortages of the Conoscopic Holography measurement system were analyzed and resolved based on theories about geometrical optics, crystal optics and polarization optics. Compared to the problems of light intensity on hologram, which is easy to be disturbed by light source fluctuation and noise, measured information can be obtained from phase of fringe on hologram easily. And this method also utilized translation charactor of conscopic light in the crystal fully. Based on these analysis, measurement expression based on phase of Conoscopic Holography measurement system was proposed, which reduces the system demand on stability of light source.Technology on noise suppression was researched. According to orientation characteristics of the fringe image, an improved MCD filter was proposed based on existing orientation filter ways, which accelerates the algorithm. From the crystal optics transmission model and research on fringe detection, the method of fringe scanning in a small area with integral frequency and decimal phase was used to obtain the measured information. So the two ways ware connected together. One is the method of testing fringe frequency which can recognize a pixel, and another is the method of testing fringe phase which can fix sub-pixel position. This also saved times on disposing and calculation, and accelerated measurement velocity without precision loss.To ensure Conoscopic Holography system’s high precision in large measurement range, two methods were adopted to enlarge phase difference. One is adding crystal phase of rotation and another is adding optical lens, which improves test precision of the system and reduces calibration difficulty. Research on transmition characteristic and non-linear calibration technology of the system, and theories of incremental measurement and relative phase measurement, which make the Conoscopic Holography measurement system realize incremental and relative phase measurement, which avoids difficulty in locating absolute zero point. It avoids joggle operation of image because of image’s area surpassing CCD image surface. Characteristic parameters of the system are optimized by genetic algorithm(GA). Artificial neural network(ANN) has been used to realize non-linear calibration of incremental measurement system, so non-linear error was eliminated and the difficulty of obtaining antitromic model was avoided.Analyze all the influence factors of measurement system, and compensate system error from optic elements. The method of self-adaption with PID was adopted to restrain temperature variation which can cause shifting of laser wavelength and variation of refracting index of the crystal. This way also reduces demands of the system to environment and improves environment adaptive ability of the Conoscopic Holography system.更多还原