Algorithm of Interferogram Tracing. II. Fringes with Negative Curvature and Extended Approach to Their Processing

Abstract

We describe an extended algorithm for the analysis of the interferograms of complex-structured phase objects, capable of processing the fringes with negative curvature. The algorithm implements nonlinear locally-adaptive processing of interference images, which is based on the analysis of the distribution, variance, and increment of intensity in different directions at each point of the image. The employed algorithm allows iterative removal of noise and distortions without loss in the fringe contrast as well as provides a means to determine the local path of each fringe. The method for the search of extreme points with an account of the intensity behavior in different directions is described together with the criteria of drawing lines (fringe traces) connecting these points. The extended algorithm is tested in the context of analyzing the interference patterns of complex-structured spark channels developing from the surface of a point cathode in ambient air.