载频电子散斑位移场分离技术研究

Isolation of Displacement Fields in ESPI by Use of a Carrier Method

提出了载波调制分离位移场的方法。在双光束电子散斑干涉(ESPI)中增加参考光,使这路参考光为两光束所共用。通过偏转物体引入载波调制条纹,具有条纹对比度高的优点。物体加载后,载波条纹受物体变形的调制而发生弯曲变形。实验时,两束光各自独立地对变形物体进行测量,采集物体变形前后的条纹,利用傅里叶变换法,可分别解调得到包含离面和面内位移信息的2幅位移图。理论分析表明,只需简单的位相运算,就能够将面内位移场与离面位移场分离。利用典型的周边固定、中心加载的圆盘实验,表明了该方法的可行性;周边固定、中心加载的圆盘变形所包含的面内位移大小与离面位移相比,大约低1个数量级。

A novel carrier method to isolate out-of-plane displacement from in-plane displacement is presented. A reference is added to dual beam symmetric illumination ESPI system and shared by the two illuminations. The way to introduce carrier by tilting the test object enjoys high fringe visibility. When the object is loaded,the cartier will be curved due to the modulation of deformation of the object surface, The two illumination lights are used separately in experiment, With the carrier and the modulated carrier, two phase maps, which include out-of-plane and in-plane displacement, can be derived by Fourier transform. Theoretical analysis shows that out-of-plane displacement can be separated from in-plane displacement only by simple calculation of phase. This method has been proved to be feasible by a typical experiment using a centrally loaded clamped circular plate. Some results are offered,which show that the magnitude of in-plane displacement of the circular plate is one order lower than that of out-of-plane displacement.