CFT-based Newton ring parameter estimation method

Abstract

The invention discloses a CFT-based Newton ring parameter estimation method, and belongs to the field of optical measurement. The method comprises the following steps: converting the gray value of theNewton ring into [0, 1]; calculating the difference between two adjacent rows; randomly selecting K rows from the results; applying discrete time chirp-Fourier transform to calculate an amplitude spectrum; taking the amplitude spectrum as a cost function of ALO; optimizing to obtain K groups of optimal values; utilizing an outlier detection algorithm to remove outliers and calculating the averagevalue based on the residual result to obtain the optimal value point, estimating the phase parameter according to the impulse characteristic of the Newton ring in the CFT domain, and then obtaining the measured value of the curvature radius. Therefore, compared with a traditional Newton ring measuring method, the method has better noise and shielding robustness and has the advantages of low calculation complexity, high precision and high speed.

Description

technical field [0001] The invention relates to a CFT-based Newton ring parameter estimation method, which belongs to the field of optical measurement. Background technique [0002] Interferometry is an optical measurement technology that obtains physical parameters through interference fringes, and has important application value in engineering metrology, optical metrology, seismic, spectroscopy and other fields. As one of the classic quadratic phase interference fringes, Newton's ring has a wide range of applications in interferometry, such as judging the concave and convex of the lens surface, measuring the radius of curvature of the lens surface and the refractive index of liquid, etc. [0003] With the emergence of optoelectronic technology, modern signal processing theory can be applied to interferometry, forming a new research field where signal processing intersects with traditional interferometry. This new intersecting field of research applies some modern signal p...

AI Technical Summary

Problems solved by technology

These methods improve the noise and obstacle robustness in traditional interferometry, but these methods still have some disadvantages

For example, when finely determining fringe parameters, the method based on Fourier transform needs three iterations to separate a sideband, and the iterative process takes a long time; the method based on wavelet transform can extract the frequency characteristics of interference fringes in any local range, but There are still problems such as threshold selection, window size selection and time-consuming; the method based on wavelet transform has better time-frequency local analysis ability, but the selection of wavelet function is still a difficult point; the method based on FRFT uses two-dimensional interference fringes and Traversal search to obtain matching angles, speed and accuracy cannot be guaranteed at the same time

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