Research Of Two-wavelength Speckle Pattern Interferometry Based On Wavelet Analysis

Speckle pattern interferometry is an optical measuring method with the character of non-destructive, high sensitivity and high accuracy. This method can realize dynamic and full-field measurement of surface roughness, displacement, deformation, vibration, stress and strain. For its simple optical structure and high accuracy, speckle pattern interferometry has been widely used in aerospace engineering, machinery manufacturing and biomedical science. For these reasons, many new methods and algorithms for speckle pattern interferometry emerge. In this paper, we focus on the displacement measurement involved two-wavelength, wavelet analysis and wavelet packet analysis in it.The main works of this paper as follows:1) We involve two-wavelength measuring method into temporal speckle pattern interferometry and make research on both theoretical derivation and experiments. We arrange the two-wavelength system with two different wavelength as473nm and532nm. After that, we acquire the two-wavelength speckle pattern correlation fringes and retrieve the phase information from these correlation fringes.2) We acquire the phase information based on wavelet ridge algorithm.In our research we use three types of typical wavelet function to retrieve the phase information. By comparing the results of the displacement information with the actual displacement, we compare and evaluate the effect of the retrieve results for each wavelet function.3) The filtering programs based on wavelet packet analysis are made. By the research of using the filtering programs to the simulated signals and the signals we acquired from the CCD camera, we testing the effect of our programs. And the results show that the filtering programs can reduce the noise in the signals and it can be used as an effective preprocessing method in the speckle pattern interferometry.