Digital speckle correlation method based on wavelet transform using micro-displacement measurement

As an un-damage measurement technique, the digital speckle correlation method (DSCM) has been used in many measurement applications by advantage of its fast, sample and low requirement of the environment. However, its calculation efficiency and the accuracy were poor. Here, a novel digital speckle correlation method based on wavelet transform was proposed. Firstly, the dynamic speckle patterns generated by the sample were recorded, and then, the multi-scale analyse of wavelet transform were using in DSCM. Furthermore, employing the optimum noise reduction strategy, the dynamic speckle patterns were decomposed using symlets wavelet family, after that, the correlation registers were conducted. In this study, the efficiency and accuracy of this method were thoroughly investigated by theories and experiments. Compared to the traditional DSCM, the accuracy of this new method is improved dramatically and the relative error is less than 1%. Furthermore, the calculated consuming time is decreased to half of the traditional DSCM.