Speckle Pattern Interferometry For Deformation Measurement

Speckle pattern interferometry is a nondestructive, full-field optical measurement technology of measuring optical rough surface. It developed based on speckle technology, laser interference technology, electronic technology, precision testing technology and computer image processing technology.The technology of measuring displacement and deformation based on principle of speckle pattern interferometry is studied in this paper. The speckle patterns are obtained in two ways of Fresnel speckle method and image plane speckle method. Two patterns of speckle interference field before and after deformation are recorded by CCD camera and stored in computer. After subtracting and taking the absolute value, the correlative fringe pattern including object's deformation information is acquired.Some often used filtering methods to the electronic speckle pattern based on MATLAB are investigated in the paper. The speckle pattern is processed in spatial domain and frequency domain and the obvious results are given. Compared with the results, synthesized filter is proposed in the paper. The contrast of interference pattern is increased and high SNR of the speckle fringe pattern is realized.At last, proposing scanning central row method. From the one dimension phase distribution of central row, one dimension deformation is obtained and interference fringes interpreter is automatically realized.