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Angular-displacement measurement with the digital-speckle correlation method

When coherent light is reflected off a rough surface, the scattered wavelets are perceived in the observation plane in the form of intensity. The strength of the intensity variations in the speckle pattern relies on the dynamics of the object as well as the optical system between the object and CCD (Charge-Coupled Device) detector. By advantages of digital speckle correlation method and statistical properties of rough surface, angular displacement based on ABCD matrix is presented. The relation between the surface rotating angle and cross correlation coefficient is realized in experiment. Furthermore, the speckle patterns captured by computer are calculated using curve fitting method. It shows that the algorithm can increase the accuracy effectively.