High resolution deformation measurement method using one sheet of speckle gram

A high-resolution new fringe analysis method based on Hilbert transformation is proposed by using the features of speckle interferometry. Hilbert transformation that is used widely in communication systems as the filter technology is the complex signal processing technology. And, the transformation can produce the analytic signal that has phase difference; pi/2 rad. This transformation is also an effective method in fringe scanning method. In the proposed fringe scanning method for speckle interferometry in this paper, the transformation is not applied to the speckle grams, but to directly speckle patterns. The simulation based on the principle of proposed fringe analysis is performed by using the simple intensity distribution model of the speckle patterns. The validity of the principle of the method and the usefulness of the method are shown in the simulation. The experiments show that the difference between the results by the new and the ordinary methods is about 0.54 rad (1/12wave) as standard deviation.