Phase Extraction Method of Digital Moire Fringe Combining Wavelet Analysis and Low-pass Filtering

Abstract

The invention discloses a digital moire fringe phase extraction method combining wavelet analysis and low pass filtering and belongs to the optical measurement and image processing technology field. The method is characterized by using actual interference graph and phase-shift virtual interference graph moire synthesis to generate a phase shift moire composite graph, and using low pass filtering and combining a phase shift interferometry to extract a preliminary result of a moire fringe phase; according to a virtual interference wavefront acquired by a virtual interferometer, combining a filtering radius of a filter to determine a distribution center and a range of a low pass filtering error in the preliminary result of the moire fringe phase; after a low pass filtering error range and the center are positioned, carrying out wavelet decomposition on the preliminary result containing the low pass filtering error; and according to the positioned error center and the range, processing a wavelet coefficient so that the filtering error can be removed, according to an approximation coefficient and a processed wavelet coefficient, carrying out reconstruction and acquiring the moire fringe phase where the low pass filtering error is removed, which means that a measurement range of digital moire interference measurement is expanded.

Description

technical field [0001] The invention relates to a digital moiré fringe phase extraction method combining wavelet analysis and low-pass filtering, which belongs to the technical field of optical measurement and image processing. Background technique [0002] The principle of digital Moiré interferometry is to use the computer to calculate the virtual interferogram according to the actual interferometer optical path and the complex standard measured wave surface, and collect the measured wave surface of the actual interferometer in real time during the actual detection to form the actual interferogram. Moiré fringes are obtained by Tumor synthesis, [0003] The light intensity distribution in the virtual interferogram satisfies [0004] [0005] where I 1 (x,y) is the background DC component of the interferogram, γ 1 is the fringe contrast, δ R (x, y) is the remaining wavefront between the measured surface and the reference surface in the virtual interferometer, its siz...

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Problems solved by technology

[0021] In order to solve the problem that the sum frequency term and the difference frequency term of the moiré composite diagram cannot be separated by conventional low-pass filtering due to the too large spectral bandwidth of the remaining wavefront of the interferogram, the technical problem to be solved by the present invention is: to provide a The digital moiré fringe phase extraction method combined with wavelet analysis and low-pass filtering can effectively expand the measurement range of digital moiré interferometry

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