外差干涉实时成像测量技术的研究

Heterodyne interferometry is widely used in ultra-precision measurement, precision machining, aerospace industry and other fields because it is non-contact, high precise, strongly immune to disturbance and so on. However, the measurement efficiency is compromised as only point measurement has been realized in heterodyne interferometry. Meanwhile, there is high requirement of the stability of frequency-shifting devices, for the fixed introduced frequency difference cannot be adjusted according to the motion characteristics of the measured object. To address these problems, real-time imaging method of heterodyne interferometry is proposed in this application. With this method, high accurate slice images of the object changing with time can be obtained in a real-time style. Besides, the introduced frequency difference based on electro-optic effect can be adjusted due to its wide working frequency band. In addition, two-wavelength measuring method is introduced in this application to expand measurement range. To solve the problem that two-wavelength method needs to be done twice in measurement, a new phase recovery algorithm based on extracting wavelet ridge is proposed to make sure the measurement can be done in a single time, therefore improving the measuring speed. The new method has features of highly precision, strong immunity to disturbance, large measurement range, being real-time measurement and so on. It will play an important role in the measurement of mechanical engineering, material science and other fields.

外差干涉测量技术由于具有测量精度高、抗干扰性强、非接触等特点，在超精密测量、精密加工、航空航天等领域有着广泛的用途。但目前的外差干涉方法只能进行点测量，影响了测量效率；同时由于引入的频差是固定的，因此无法根据被测对象的运动特性进行调节，增加了对频移器件稳定性和系统的要求。针对这些问题，本申请提出了可调整的外差干涉实时成像测量方法，可以高精度实时获取物体随时间变化的切片三维图像，同时工作频带可以根据被测对象的运动特性灵活进行调整。另外，在干涉测量中，为扩大测量范围，经常采用双波长测量的方法，但目前的双波长测量需要重复进行二次实验，不具有实时性。针对这一问题，本申请还提出了双波长实时测量技术。该方法是一种新的小波相位复原算法，使双波长测量可以一次完成，提高了测量速度。本申请所提出的新技术具有高精度、抗干扰、大量程、实时测量等特点，将在机械工程、材料科学等领域发挥较大作用。

目前外差干涉测量存在的主要问题是：.(1).属于点测量技术，不能实时进行面测量，因而当被测物体受到力、热加载后随时间发生形变时，目前的外差干涉方法难以获取实时的全场形变信息；.(2).外差调制频率不可改变，无法根据被测对象的运动特性进行调整，增加了对频移器件稳定性和系统的要求。. 针对以上问题，在本课题组发明的新铌酸锂电控外差装置的基础上，提出了新的外差干涉成像测量技术。本项目基本按照研究计划进行，完成了研究计划中的主要任务，通过执行本项目，课题组分别构建了一套三波长三维干涉实时测量装置、一套外差显微干涉实时测量装置、一套基于Wollaston棱镜的外差剪切散斑干涉实时测量装置、一套基于Rochon棱镜的剪切散斑干涉实时测量装置和一套基于实时散斑干涉测量方法的分离式霍普金森压杆测量系统，完成了原理实验，取得了较好的实验结果，将在机械材料、航天航空工程专用材料及微小器件材料的性能测试、装配和安全性评价方面有广泛的应用前景。以上述创新点申请的美国发明专利“Method for Full-Field Measurement Using Dynamic Laser Doppler Imaging” 获批，此外在本项目执行期间，课题组共发表论文10篇，其中发表SCI检索论文9篇，核心期刊论文1篇，获批国家发明专利1项。