【作者】 吴思进；

【导师】 冯其波； 杨连祥；

【作者基本信息】 北京交通大学 ， 光学工程， 2012， 博士

【摘要】 数字剪切散斑干涉术可以直接测量位移空间梯度,且具有分辨率高、全场测量、非接触式和抗干扰能力强等优点,在应变测量、振动分析、无损检测等领域均得到了广泛的应用,已成为检测领域的一个研究重点,并出现了很多类型的数字剪切散斑干涉方法与装置。其中,迈克尔逊型数字剪切散斑干涉术具有剪切方向和剪切量容易调节、相移技术容易实现等显著优点,成为应用最广泛的一种类型。但是传统的迈克尔逊型数字剪切散斑干涉存在以下三个方面的问题：一是由于结构的限制导致其视场角较小,不超过28。；二是现有的原位相移标定技术主要采用条纹分析和数学统计等方法,其数学模型的准确性对标定精度影响较大,造成标定数据不可靠；三是现有的迈克尔逊型频闪数字剪切散斑干涉仪应用范围有限,只适用于小目标的测试,无法满足大目标振动测量的要求。针对迈克尔逊型数字剪切散斑干涉存在以上三个方面的问题,本论文在全面分析国内外相关研究的基础上,主要开展扩大视场角、原位相移标定技术等方面的研究,研制适用于大面积振动测量的迈克尔逊型频闪数字剪切散斑干涉检测装置,以满足工程应用领域大目标测试和高精度标定的需要。概括起来,本论文的主要工作和创新点如下：1.提出了一种用4f光学系统扩展迈克尔逊型数字剪切散斑干涉系统视场角的新方法。理论分析与实验研究均表明：基于4f光学系统的新型迈克尔逊型数字剪切散斑干涉系统的视场角不受结构的限制,而只取决于成像镜头的焦距和数字相机中传感器的尺寸,突破了传统迈克尔逊型数字剪切散斑干涉系统视场角最大为28。的限制,实现了大视场角测量。2.提出了一种基于光学方法的原位相移标定技术,在迈克尔逊型数字剪切散斑干涉术中实现了在线自动相移标定,避免了模型不准确性带来的标定误差,提高了相移标定的可靠性,且可以实现任意相移角度的标定。3.研制出一种基于改进型迈克尔逊结构的频闪数字剪切散斑干涉仪样机,可在1.5m工作距离下对1.2m×0.9m面积物体进行振动测量,实现了大面积的振动测量。论文给出了频闪数字剪切散斑干涉仪具体设计方法,包括光路设计、电子控制系统设计和软件编程等；进行了相应的实验研究,验证了研制干涉测量装置的可行性和有效性。实验结果表明：所研制的剪切散斑干涉仪样机能实现较短工作距离下大面积的振动测量、位移空间梯度测量和无损检测等应用。更多还原

【Abstract】 ABSTRACT:Digital shearography is a well-established tool for strain measurement, vibration analysis, and non-destructive testing, because it can measure spatial derivatives of displacement directly, and has advantages of high resolution, full-field measurement, non-contact testing, and high interference immunity. It has been a popular research topic and many kinds of shearing devices have been employed in it. Among those shearing devices, the most popular one is the modified Michelson interferometer, with which the digital shearography is called the Michelson-type digital shearography. Michelson-type digital shearography enjoys several advantages, such as being easy to adjust the shear direction and amount, and being easy to carry out the temporal phase shift technique. However, it should be improved in some areas. Firstly, the view angle is limited by the structure and cannot exceed28°. Secondly, the present in situ phase shift calibration techniques are all based on pattern analysis and statistical methods, which will lead to unreliable calibrations in some case. Finally, most digital stroboscopic shearographic devices are not suitable for measurement of large object.This thesis focuses on the studies of the Michelson-type digital shearography. A method to enlarge the view angle and an in situ phase shift calibration technique are proposed. A stroboscopic Michelson-type digital shearographic device for vibration measurement of large object is developed.The main innovations of this thesis consist of:1. A method that embeds a4f optical system into the shearographic system optical arrangement to enlarge the view angle is presented. The theoretical analysis and experimental research both reveal that the new Michelson-type digital shearography with4f optical system can break through the28°view angle limitation. The view angle will no longer be limited by the structure, but only depend on some parameters of the digital camera. Thus wide view angle in Michelson-type digital shearography is easy to achieve.2. An in situ phase shift calibration technique based on optical method is introduced. It is an on-line method that can calibrate the phase shift automatically. It uses optical method rather than statistical method, so the calibration results are more reliable and arbitrary phase shift angle can be calibrated.3. A stroboscopic digital shearographic prototype based on modified Michelson interferometer is developed. It can achive the vibration measurement on a large erea The measuring field can reach an area of1.2m×0.9m at1.5m work distance. The design details of the prototype, including optical design, electronical design, and programming, are given in the thesis. Some experiments are also conducted to show the performances of the prototype. The experimental results prove that it is suitable for the applications of vibration measurement, displacement derivatives measurement, and non-destructive testing.更多还原