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Time-phase unwrapping method based on dual-frequency three-gray-scale sinusoidal grating fringe projection

A sinusoidal grating and fringe projection technology, which is applied in the field of optical measurement, can solve the problems of time-consuming and low measurement speed, and achieve the effect of improving measurement speed and ensuring measurement accuracy

Inactive Publication Date: 2016-07-06
NANJING UNIV OF SCI & TECH
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Problems solved by technology

However, in the commonly used methods at present, it is usually necessary to use at least 6 grating fringes to solve the absolute phase without wrapping and realize the reconstruction of a 3D image, which is time-consuming and the measurement speed is low.

Method used

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  • Time-phase unwrapping method based on dual-frequency three-gray-scale sinusoidal grating fringe projection
  • Time-phase unwrapping method based on dual-frequency three-gray-scale sinusoidal grating fringe projection
  • Time-phase unwrapping method based on dual-frequency three-gray-scale sinusoidal grating fringe projection

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Embodiment Construction

[0023] Such as figure 1 As shown, the present invention is based on the time phase unwrapping method of dual-frequency three-gray-scale sinusoidal grating fringe projection, comprising the following steps:

[0024] Step 1. Generate dual-frequency ideal sinusoidal fringes:

[0025] Use computer to generate five ideal sinusoidal fringes, three of which have a wavelength of λ 1 , the phase difference is The wavelength of the other two ideal sinusoidal fringes is λ 2 , the phase difference is

[0026] The three wavelengths are λ 1 The light intensity distribution of the ideal sinusoidal fringe satisfies formulas (1), (2) and (3) in turn:

[0027] I 1 p (x p ,y p )=A p (x p ,y p )+B p (x p ,y p )cos(2πx p / λ 1 -2π / 3)(1)

[0028] I 2 p (x p ,y p )=A p (x p ,y p )+B p (x p ,y p )cos(2πx p / λ 1 )(2)

[0029] I 3 p (x p ,y p )=A p (x p ,y p )+B p (x p ,y p )cos(2πx p / λ 1 +2π / 3)(3)

[0030] The two wavelengths are λ 2 The light intensity ...

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Abstract

The invention discloses a time phase unwrapping method based on double frequency three-gray-scale sinusoidal grating fringe projection. The method comprises the steps that two sets and five ideal double-frequency sinusoidal grating fringes are generated by utilizing a computer, then three-gray-scale sinusoidal grating fringes corresponding to the ideal double-frequency sinusoidal grating fringes are generated by adopting the three-gray-scale space pulse width modulation technology, under condition that that a projector keeps the defocusing state, the five three-gray-scale sinusoidal grating fringes are projected to the surface of an object to be measured, two sets of wrapped phase images are solved, wherein the five double-frequency fringes comprise the two sets of wrapped phase images, the fringe order corresponding to the wrapped phase is solved, and unwrapping of the wrapped phase is achieved. The time phase unwrapping method based on the double frequency three-gray-scale sinusoidal grating fringe projection improves measurement precision and measurement speed.

Description

technical field [0001] The invention belongs to the technical field of optical measurement, and in particular relates to a time phase unwrapping method based on dual-frequency three-gray-scale sinusoidal grating fringe projection. Background technique [0002] In order to achieve high-speed and high-precision 3D measurement, it is necessary to ensure high-quality sinusoidal fringe projection. In the current traditional methods, most of them still use the method of directly projecting sinusoidal gratings. The directly projected sinusoidal fringes are easily affected by the nonlinear effect of the projector, and become non-sinusoidal grating fringes, which will greatly affect the final measurement. precision. In order to reduce the influence of the nonlinearity of the projector, Zhang Song et al. proposed a measurement error compensation method to overcome the nonlinear effect in the article "Generic nonsinusoidal phase error correction for three-dimensional shape measurement...

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): G01B11/25
Inventor 陈钱冯世杰顾国华左超孙佳嵩喻士领申国辰李如斌
Owner NANJING UNIV OF SCI & TECH
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