Method for solving phase error overcompensation and undercompensation in phase measurement profilometry

A technology of phase measurement profile and phase error, which is applied in the field of phase error overcompensation and undercompensation, and phase error compensation in phase measurement profilometry, and can solve problems such as overcompensation, phase error, and undercompensation.

Inactive Publication Date: 2014-03-05
SOUTHEAST UNIV
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Problems solved by technology

[0004] The purpose of the present invention is to propose a solution to phase error over-compensation and under-compensation in phase measurement profilometry, to solve the impact of ambient light changes on ph...

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  • Method for solving phase error overcompensation and undercompensation in phase measurement profilometry
  • Method for solving phase error overcompensation and undercompensation in phase measurement profilometry
  • Method for solving phase error overcompensation and undercompensation in phase measurement profilometry

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Embodiment Construction

[0049] Take the 3D measurement using the four-step phase shift method as an example.

[0050] In the phase error compensation preprocessing, the projector projects all black, all white, four-step phase shift and sixteen-step phase shift images to the measured object, and collects the corresponding images. The purpose of projecting a sixteen-step phase-shifted image is to calculate an accurate absolute phase.

[0051] According to formula (19), the phase error consists of two parts, where It is the phase error coefficient related to the system gamma value and ambient light, and sin4φ is the harmonic normalized phase error related to the absolute phase measurement in theory. The two parts are determined separately.

[0052] In this embodiment, for the harmonic normalized phase error sin4φ, considering the random error in the measurement, it is determined by the method of curve fitting, and the specific steps are as follows:

[0053]1) Solve the absolute phase of the acquired ...

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Abstract

Provided is a method for solving phase error overcompensation and undercompensation in phase measurement profilometry. Based on an optical three-dimensional measurement method, a raster image is projected to an object surface, raster information modulated by an object surface profile is collected, the height of the object surface is restored, a projector, a CCD camera, an object to be measured and a computer are included, the projector projects a sinusoidal grating, the camera collects the deformed sinusoidal grating after object surface height modulation, the gamma nonlinearity of the projector and the camera and the influence of measuring environment light in the measurement process are considered, when phase errors are compensated in actual measurement, the projector projects completely black images, completely white images four-step phase shift images to the object to be measured, an environment light parameter t is calculated through the collected completely black images and completely white images, an absolute phase phi is calculated through a four-step phase shift phase solution method, the two parameters are substituted into a phase error penalty function, and a phase delta phi used for compensation can be obtained.

Description

technical field [0001] The invention relates to a phase error compensation technology in phase measurement profilometry, in particular to a solution to phase error over-compensation and under-compensation in phase measurement profilometry, and belongs to the technical field of machine vision. Background technique [0002] Phase measurement profilometry is a commonly used optical three-dimensional measurement method. By projecting a grating image onto the object surface and collecting the grating information modulated by the object surface profile, the height of the object surface can be restored. A typical object surface profile measurement system based on grating projection consists of a projector, a CCD camera, an object to be measured and a computer. Due to design reasons, both the digital projector and the CCD camera have the non-sinusoidal effect of the grating caused by the gamma nonlinear transformation, which causes an error in the phase value containing the object c...

Claims

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Application Information

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IPC IPC(8): G01B11/25
Inventor 周平刘欣冉
Owner SOUTHEAST UNIV
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