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A 3D Measurement Method Based on Pulse Width Modulation Fringe

A pulse width modulation, three-dimensional measurement technology, used in measurement devices, instruments, optical devices, etc., can solve problems such as restricting measurement speed, achieve fast measurement speed, overcome measurement depth, and reduce fringe contrast.

Active Publication Date: 2018-07-20
SHANGHAI SUPORE INSTR
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  • Application Information

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Problems solved by technology

In terms of fringe type, because the traditional sinusoidal fringe is an 8-bit grayscale image, its grayscale value is distributed between 0-255, and the projection speed is limited within 120HZ, which restricts the measurement speed; in terms of electronic equipment properties, Since today's three-dimensional measurement systems are all fringes with characteristic information projected by DLP, the measurement error caused by the high-order harmonics caused by the nonlinear gamma effect of electronic equipment is an inevitable problem

Method used

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  • A 3D Measurement Method Based on Pulse Width Modulation Fringe
  • A 3D Measurement Method Based on Pulse Width Modulation Fringe
  • A 3D Measurement Method Based on Pulse Width Modulation Fringe

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Embodiment Construction

[0018] The embodiments of the present invention will be described in further detail below in conjunction with the accompanying drawings, but the present embodiments are not intended to limit the present invention, and any similar structures and similar changes of the present invention should be included in the protection scope of the present invention.

[0019] A three-dimensional measurement method based on pulse width modulation fringes, comprising the following steps:

[0020] (1) Encoding of pulse stripes.

[0021] a. An ideal sine wave with a four-step phase shift function is generated by a computer:

[0022] (2)

[0023] Among them, T is the number of cycles, y is the pixel of the sine wave, s is the step size, and m is the number of phase shift steps (=1,2,3,4). Such as figure 2 As shown by the red line in (a), the phase-shifted sine wave with a cycle number of 1 and a phase shift step of 1, the frequency is recorded as f s .

[0024] b. Generate a set of trapez...

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Abstract

The invention discloses a three-dimensional measurement method based on a pulse width modulation fringe. The three-dimensional measurement method consists of three key parts of pulse fringe encoding, pulse fringe defocusing and three-dimensional reconstructing. A pulse fringe is generated from a computer and then moderately defocused through a projector to generate a sine fringe on a reference face for three-dimensional measurement. The invention is advantageous in that (1) as the pulse fringe is a binary fringe, the grayscale value thereof can only be two values (0 and 1), so the measurement is quick; (2) since the nonlinear gamma of the projector can be eliminated simply by slight defocusing the projector, phase errors can be reduced without complex nonlinear calibration; and (3) thanks to less reduction in fringe contrast after the pulse fringe is slightly defocused, the measurement depth problem is overcome.

Description

technical field [0001] The invention relates to an optical three-dimensional measurement method, which belongs to the technical field of photoelectric detection. In particular, it relates to a three-dimensional measurement method based on pulse width modulated fringes. Background technique [0002] With the intersecting and multi-integrated development of science and technology, the three-dimensional measurement method based on optics, electricity, image processing and computer vision has become an industrial non-destructive testing method with broad application prospects. The structured light three-dimensional measurement system formed by this method has been widely used in many fields such as industrial manufacturing, cultural relics protection, medical treatment, etc. play an important role. In order to meet the fast pace of production and life, three-dimensional measurement speed has become an important index to measure the measurement system; at the same time, with th...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): G01B11/25
Inventor 伏燕军李彪曾灼环
Owner SHANGHAI SUPORE INSTR
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