Two Computer-Aided Methods For Data Reduction From Interferograms

There are various methods for the data reduction from interferograms. At present the fringe method and the phase-shifting method are widely used. In the fringe method a skeleton of the fringe pattern is derived automatically and the phase distribution and the dis-placement field, respectively, is evaluated interactively from that skeleton. In the phase-shifting method a set of phase-shifted interferograms is used for the calculation of a relative phase at any point of the object under test. Both methods are implemented on a commercial image processing system, including a video processor, that enables to process images at video rate. Due to some practical experiences in holographic and speckle-inter-ferometry the advantages and disadvantages of both methods are discussed and their ranges of application are considered.