High-accuracy parameter estimation from Newton’s rings using zero-padded Chirp-Z transform

Newton’s rings are a classic optical fringe pattern characterized by a quadratic phase. They play a critical role in spherical measurements and optical interferometry. However, analyzing these patterns presents significant challenges. We propose an accurate method for processing Newton’s rings interference fringe patterns. The method involves a blockwise Fourier transformation of the interferogram. This is followed by the total least squares fitting to estimate the ring center. The signals are then stitched together using a specific algorithm. Finally, a zero-padded Chirp-Z transform is applied to estimate the radius of curvature. The proposed method achieves ring center estimation accuracy within ∼1 pixel on actual images. The average relative error in the radius of curvature is <0.1%, demonstrating strong robustness. This method provides an effective solution for analyzing Newton’s rings patterns. It enhances accuracy by improving both computational and physical resolution, and it makes valuable contributions to fringe analysis.