Effect of image patch size on phase difference determination by fringe pattern matching

The effect of image patch size on phase difference determination by fringe pattern matching is discussed, The standard deviations based on the measurements from different sizes of image patches are derived from the statistical analysis of the fringe pattern matching process. The effect of image patch size on phase difference determination is examined by both computer simulation and experimentation. The background noise levels of interferograms are obtained by computer generated speckle noise, Gaussian noise and salt and pepper noise added to ideal fringe patterns, and the results from different sizes of image patches were acquired by fringe pattern matching in the simulation. The experimental results were also achieved from different sizes of image patches. The computer simulation and experimental results have shown that the larger image patches have a better accuracy in the presence of noise, which is in accordance with the results from theoretical analysis. (C) 1997 Society of Photo-Optical instrumentation Engineers.