A Self-calibration Shadow Moiré 3D Profile Measurement Method

A measurement method and technology of three-dimensional profile, applied in the direction of measuring devices, instruments, optical devices, etc., to achieve the effects of saving measurement time, simplifying the technical level, and accurate calculation process

Active Publication Date: 2019-01-18
XIAN TECH UNIV
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Problems solved by technology

It should be mentioned that although Wang's algorithm can reduce the influence of the fringe pattern background on the demodulation result, the demodulation result of this method has a displacement relative to the measured phase
So there is a problem in height measurement occasions

Method used

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  • A Self-calibration Shadow Moiré 3D Profile Measurement Method
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  • A Self-calibration Shadow Moiré 3D Profile Measurement Method

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Embodiment 1

[0050] see figure 1 and figure 2 , the device used in the present invention is a conventional device, including a CCD camera 2, a line light source 1, a grating 4 and a motorized translation stage 3, the optical axis of the CCD camera 2 is perpendicular to the grating surface, and the center of the light source of the CCD camera 2 and the line light source 1 is placed The distance from the plane L where the grating 4 is located, the distance between the line light source 1 and the center of the CCD camera 1 is d.

[0051]During measurement, the object to be measured 5 is set at the measurement position. A self-calibration shadow moiré three-dimensional profile measurement method, comprising the following steps in sequence:

[0052] Step 1: Place the measured object in the measurement space, turn on the light source, and use the camera to record the resulting fringe pattern. Specifically, place the workpiece in the measurement space and initialize it through the virtual inst...

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Abstract

The present invention belongs to the optical precise measurement technology field, in particular relates to a self-calibration shadow Moire three-dimensional contour measurement method. The self-calibration shadow Moire three-dimensional contour measurement method orderly comprises a first step of placing a measured object in the measurement space, turning on a light source, and using a camera to record a generated fringe diagram; a second step of utilizing a precise displacement bench to move an optical grating two times with a predetermined distance and in an equal step length manner, and recording the fringe diagrams generated after each time of movement; a third step of pre-processing the acquired fringe diagrams, and utilizing a fringe noise reduction method to remove the high-frequency noise signals in the images; a fourth step of demodulating the phases of the signals in the fringe diagrams; a fifth step of utilizing an unwrapping method to unwrap the above extracted measurement phases; a sixth step of utilizing a following formula to carry out the phase-height mapping according to the calculated phases and the measurement sensitivity, thereby finishing a measurement task. By just needing to measure three fringe diagrams, the measurement method of the present invention saves the measurement time, and is accurate and convenient in calculation process.

Description

technical field [0001] The invention relates to the technical field of optical precision measurement, in particular to a three-dimensional profile measurement method for phase-shift shadow moiré using three-frame fringe images. Background technique [0002] Shadow Moiré 3D profile measurement technology is a full-field, non-contact optical 3D profile measurement method. Since it was proposed in 1970, it has been widely used in human body measurement, wafer surface inspection, BGA coplanarity test, automatic production, aviation industry and other fields. [0003] Early shaded moiré techniques were mainly based on the moiré contour method. The Moiré contour method is simple and intuitive, but it cannot effectively use the gray level information of the fringe spacing, and its measurement sensitivity is limited to one fringe spacing. [0004] The Fourier-based shadow moiré method introduces a carrier frequency into the measurement field of view by tilting the measured object,...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): G01B11/25
CPCG01B11/2504G01B11/254
Inventor 杜虎兵颜菁菁刘海涛王建华
Owner XIAN TECH UNIV
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