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Digital Moire fringe phase extraction method based on nonlinear optimization

A non-linear optimization and moiré fringe technology, which is applied in image data processing, measuring devices, instruments, etc., can solve the problem of large spectral bandwidth, and the inability of low-pass filtering and separation of the sum and difference frequency items of the moiré composite image problems, to achieve the effect of extending the measurement range

Active Publication Date: 2017-07-07
BEIJING INSTITUTE OF TECHNOLOGYGY
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Problems solved by technology

[0016] In order to solve the problem that the sum frequency item and the difference frequency item of the moiré composite image cannot be separated by conventional low-pass filtering due to the too large spectral bandwidth of the remaining wavefront of the interferogram, the present invention provides a digital moiré filter based on nonlinear optimization. Fringe Phase Extraction Method, Effectively Expanding the Measurement Range of Digital Moire Interferometry

Method used

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  • Digital Moire fringe phase extraction method based on nonlinear optimization
  • Digital Moire fringe phase extraction method based on nonlinear optimization
  • Digital Moire fringe phase extraction method based on nonlinear optimization

Examples

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Embodiment 1

[0064] This example is based on MATLAB simulation to verify the theoretical feasibility of the method.

[0065] The flow of a digital Moiré fringe phase extraction method based on nonlinear optimization is as follows: figure 1 As shown, the specific steps are as follows:

[0066] Step 1: Establishing a standard mathematical model of the light intensity distribution of the moiré composite map.

[0067] The light intensity distribution in the virtual interferogram satisfies

[0068]

[0069] The light intensity distribution in the actual interferogram satisfies

[0070] I o (x,y)=I 2 (x,y){1+γ 2 cos[2πf o x+δ o (x,y)]}

[0071] The above two formulas can be obtained by multiplicative Moiré synthesis after removing the DC background term

[0072]

[0073] When f in the above formula R = f o = f, I 1 (x,y)=I 2 When (x, y)=I, and make Available

[0074]

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Abstract

The invention relates to a digital Moire fringe phase extraction method based on nonlinear optimization, belonging to the technical field of optical measurement and image processing. According to the method, a Moire synthesis light intensity distribution graph mathematical model is established, a fringe phase is used as an optimization variable, with actual Moire synthesis graph light intensity distribution as an optimization target, phase continuity is taken as a boundary condition, through nonlinear optimization calculation, the light intensity distribution of the mathematical model is equal to the light intensity distribution of an actual Moire synthesis graph, and the fringe phase at that time is the Moire fringe phase of the actual Moire synthesis graph. According to the method, the Moire fringe phase can be obtained without low pass filtering, a filtering error in a spectrum aliasing condition can be avoided, and a phase measurement precision is improved.

Description

technical field [0001] The invention relates to a phase extraction method of digital moiré fringes based on nonlinear optimization, 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 size and spatial ...

Claims

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Application Information

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IPC IPC(8): G01B11/24G06T7/521
CPCG01B11/2441
Inventor 郝群谭一丰胡摇王劭溥
Owner BEIJING INSTITUTE OF TECHNOLOGYGY
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