Improved accuracy and defect detection in contour line determination of multiple-beam Fizeau fringes using Fourier fringe analysis technique

An accurate and a straightforward algorithm is proposed in this article for automatic fringe analysis of the multiple-beam Fizeau fringe. The algorithm bases on the combination between the Fourier transform technique and the derivative sign binary method. The Fourier transform is the one of the most common techniques used to filter out the noise from the interference fringes. The derivative sign binary method is used to detect the edges and the contour line of the interference fringes. The comparison between the Fourier transform spectra of the two-beam and the multiple-beam interference fringes have been highlighted. The effect of the peaks of the Fourier transforms spectra on the accuracy of the contour line determination was studied. The algorithm has been successfully tested on free and noisy multiple-beam Fizeau fringes interferogram. The method presented herein is also useful for overcoming the effect of discontinuities fringes at the boundaries of the interferogram and does not need thresholds and thinning process. The obtained results were discussed and compared with a well-known method to illustrate the effectiveness of the proposed method.