Newton's ring pattern is an typical interference fringe often encountered in optical measurements. The physical parameters, such as curvature radius, the ring's center can be estimated by analyzing it. Newton ring formed by spherical interference is two-dimensional Chirp signal, and its chirp parameters are almost impossible to be integers. However, the strict constraints of discrete Chirp Fourier transform (DCFT) and the existing discrete Modified Chirp Fourier transform (MDCFT) can only estimate the integer value part of parameter, which has a large recognition error. An improved MDCFT algorithm is proposed to further estimate the non-integer value part by using the object offset principle, thereby improving the estimation accuracy of Newton ring parameters. Experimental results verify the effectiveness and correctness of the proposed method.
KEYWORDS: Computer simulations, Commercial off the shelf technology, Fringe analysis, Error analysis, Signal processing, Phase shift keying, Data centers, Signal detection, Interferometry, Phase shifts
Interferometry technology has a wide range of applications because of high accuracy and sensitivity, the core of which is
the processing of interference fringe pattern. The interference fringes with quadratic phase are very common in
interferometry measurement, which means that any sophisticated interference fringes can be decomposed or
approximatively decomposed by them. Newton’s rings are typical interference fringes with quadratic phase, the physical
parameters such as curvature radius and position of ring’s center are included in the pattern. The parameter estimation
algorithm of Newton’s rings based on FRFT/DCFT needs only one pattern to realize the estimation through the method of
signal processing with advantages of easy operation, high accuracy, high speed and strong anti-noise performance, for
reason that the Newton’s ring is actually a two-dimension Chirp signal.
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