Computer-aided evaluation method for interferograms

For the quantitative evaluation of interferograms a video camera is used to digitize the interferograms in frames up to 512 by 512 pixels which are transmitted to a host computer. Quantitative data of the whole field are obtained by the following procedure: First the fringes are extracted with the help of binarization methods. Then to each fringe boundary a value is assigned in a certain point. Starting from this point the boundaries are traced through the whole pattern. Finally the data between the fringe boundaries are determined by linear interpolation. Other operations like smoothing can be done before the results are printed.