Automatic Fringe Analysis Using Digital Image Processing Techniques

An automatic computer analysis system for interferometric patterns is developed. A digital interferogram is stored on disk memory, and fringe skeletons of the interferogram are extracted, based on the two-dimensional gray level fringe peak detection method. Extracted fringe skeletons are thinned, and then their fringe orders are determined, during which process the fringe pattern is visually inspected. The least-square interpolation method is applied to determine the fractional fringe orders of pixels between fringe skeletons. All the procedures of analyzing fringe data, except for the fringe order determination, are automatically performed. A man-machine interactive method with a light pen is used to inform the determined fringe orders to the computer. A representative example of the fringe pattern analysis is presented.