Generation method of sinusoidal grating based on regional defocusing

A sinusoidal grating and area technology, applied in the field of optical measurement, can solve the problems of low grating generation accuracy and large phase error, and achieve the effect of accurate grating generation, error elimination and convenient realization

Inactive Publication Date: 2012-11-28
NORTHWESTERN POLYTECHNICAL UNIV
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Problems solved by technology

[0006] In order to solve the problems of low grating generation accuracy and large phase error in the existing def

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  • Generation method of sinusoidal grating based on regional defocusing
  • Generation method of sinusoidal grating based on regional defocusing
  • Generation method of sinusoidal grating based on regional defocusing

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Embodiment Construction

[0028] Describe the present invention below in conjunction with specific embodiment:

[0029] For comparison, two methods for generating sinusoidal gratings are used in this embodiment, one is the traditional generation of sinusoidal gratings by square wave defocusing, and the other is generating sinusoidal gratings based on area defocusing proposed by the present invention.

[0030] A sinusoidal grating is generated by defocusing a square wave: e.g. Figure 4 As shown, square wave stripes are generated by DLP programming; Figure 4 The shown square wave stripes are projected onto the surface of the measured object, and the projection distance and projection screen size are determined according to actual needs; the projection distance between the projector and the surface of the measured object remains unchanged, and the projection screen size of the projector remains unchanged. Adjust the focal length of the projector to focus the image projected by the projector on the surf...

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Abstract

The invention discloses a generation method of a sinusoidal grating based on regional defocusing, comprising the following steps of: performing 2*2 regionalization on the connected pixels via construction; performing different binary assignments on the pixels in the regions; generating a high-accuracy triangular wave grating via defocusing; and then performing secondary defocusing on the triangular wave grating to obtain the sinusoidal grating meeting accuracy requirements. The generation method is convenient to realize, accurate in grating generation and suitable for a high-accuracy non-contact three-dimensional real-time measurement system, thus effectively solving the defects existing in the prior art. Via division and assignment for the regions of 2 pixels*2 pixels and slight defocusing, the error brought by the gamma nonlinearity problem of a projector during direct generation for the triangular wave grating is effectively eliminated, the regions of 2 pixels*2 pixels can be regarded as an integer after the step 1 and the step 2, and a triangular wave grating image meeting requirements is generated; and via the secondary defocusing in the step 3 for the high-accuracy triangular wave grating image, higher harmonic in the high-accuracy triangular wave grating image is filtered out, so that a satisfactory sinusoidal grating image is obtained.

Description

technical field [0001] The invention relates to a method for quickly generating a sinusoidal grating, in particular to a method for generating a sinusoidal grating based on area defocus. It belongs to the technical field of optical measurement. Background technique [0002] Rapidly generating sinusoidal gratings through defocusing is an important means to realize 3D real-time optical measurement. Defocusing is equivalent to a Gaussian low-pass filter, which can filter out the high-order harmonics in the input binary coded image. The accuracy of the sinusoidal grating generated by defocusing is directly related to the phase resolution accuracy and the three-dimensional inversion accuracy. [0003] Traditional methods such as directly defocusing square waves into sinusoidal gratings proposed by Song Zhang et al. 4121-4123) have the characteristics of low grating generation accuracy and large phase resolution error, which are difficult to meet the requirements of non-contact ...

Claims

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Application Information

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IPC IPC(8): G01B11/00G01B11/25
Inventor 常智勇孙惠斌李春磊卢津樊迪张栋梁
Owner NORTHWESTERN POLYTECHNICAL UNIV
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