Automatic spatial fringe analysis method for two-dimensional fringes image including phase discontinuities by obstructions

Abstract

A new two-dimensional (2D) automatic spatial fringe analysis method or analysing a fringe image including images of obstructions, such as a blade in an interferogram of pressure distribution around turbine blades, is proposed. In the analysis, first, the image of the obstruction is removed from the fringe image using the characteristics of spatial fringe analysis method. Second, the problem with respect to the phase discontinuities of the principal values of the inverse-trigonometric function is discussed. Then, the processing paths for the automatic phase-unwrapping processing are found using the concept of the directed graph. Third, fringe analysis of an image including noise is discussed by the new method. Finally, automatic 2D spatial fringe analysis can be realized with the calculation along processing paths. The experimental results show that the 2D fringe analysis for the image with obstructions can be performed accurately and automatically by the method proposed. In addition to the experiment, processing of an image with noise is discussed using the simulation by the proposed method. The simulation shows that this method is successful for processing an image with noise. An example of the application of this method to investigate the radiant heat of integrated-circuit chips is introduced.