Development of fringe analysis method for image in ESPI using single sheet of specklegram

When the spatial fringe analysis method as one of the technologies is employed in speckle method, the speckle interferometry is also improved to the high speed and high resolutive measurement method. However, there are some problems in the practical use. Generally, fringe scanning technologies are employed in speckle interferometry under restricted conditions. Another speckle pattern except these two speckle patterns before and after deformation is required in the case that the fringe scanning technology is introduced for the high precise measurement in the speckle interferometry. In this paper, the new technology that can measure the phase distribution of fringes by using only two speckle patterns before and after the deformation is proposed. In this method, a fringe image is divided into some regions which have some different characteristics mutually in Fourier domain. Consequently, each region is transformed to spatial domain by inverse Fourier transformation. Then, the fringe image is analyzed by Spatial Fringe Analysis Method in spatial domain. Because the phase map of the specklegram is analyzed by the mathematical characteristics of Fourier transformation in the new analysis method, the fringe analysis for not only monotone increase or decrease but also convex or concave information can be realized with artificial carrier information.