Real-time Measurement Method of Digital Moiré Interferometry Phase Based on Sparse Fourier Transform

Abstract

The invention relates to a digital moiré phase-shifting interference phase real-time measurement technology based on sparse Fourier transform, and belongs to the field of optical measurement. The invention firstly constructs a virtual interferogram and performs Moiré synthesis. Based on the one-dimensional sparse Fourier transform (SFFT), a two-dimensional Moiré fringe pattern rearrangement rule is designed, and a small number of large-value points in the spectrum are sparsely scattered in the spectrum through rearrangement in the spatial domain. Secondly, the window function of the two-dimensional SFFT is set, and the spatial aliasing and down-sampling FFT of the two-dimensional signal are performed to reduce the original N×N size image to B×B size, reducing the amount of subsequent calculations. After the restoration of the position coordinates and the restoration of the estimation, the restoration of the N×N spectrum is completed. Finally, the restored spectrum is used in the dephasing process of the digital Moiré phase shifting method. The invention can reduce the calculation amount of the phase resolution process, improve the algorithm speed of the digital moiré phase shift phase resolution method, and help realize the real-time measurement of the phase in precision machining, engineering practice and biomedical fields.

Description

technical field [0001] The invention relates to a real-time measurement method of digital moiré phase shifting interference phase based on sparse Fourier transform, which belongs to the field of optical measurement. Background technique [0002] The measurement of many physical quantities can be transformed into a phase measurement. For example, in the measurement of the surface shape of precision-processed optical components, the surface shape change of the measured element can be converted into the phase change of the reflected laser for measurement by using the interferometry; in the measurement of gas-liquid flow field and biological cell morphology, the thickness of transparent gas-liquid and tissue can also be measured. It can be converted into phase change of transmitted light by differential interference etc. for measurement. In the above-mentioned measurement process, since the measured physical quantity often changes with time, sometimes at a high speed, a technol...

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Problems solved by technology

[0014] The purpose of the present invention is to solve the problem that the interferogram phase of the prior art takes a long time to solve and cannot realize real-time measurement, and provides a real-time measurement method of digital Moiré phase-shifting interferometric phase based on sparse Fourier transform. Two-dimensional sparse Fourier transform, which reduces the calculation amount of Fourier transform in the phase resolution process, improves the calculation efficiency, and provides technical support for real-time phase measurement

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