3D Measurement Device Rectangular Waveform Sinusoidal Conversion
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Solution Overview
Problem
Existing three-dimensional measurement devices using the phase shift method face challenges in maintaining accurate sinusoidal light intensity distributions, leading to reduced measurement accuracy, especially when projecting striped patterns in focus, and are difficult to implement without complicating the mechanical configuration.
Innovation Solution
A three-dimensional measurement device that projects a striped pattern using a grid with alternating light transmitting and shielding portions, allowing imaging during both stop and move periods, and averaging luminance values to achieve a sinusoidal light intensity distribution, enabling focus projection and maintaining waveform accuracy without mechanical complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a striped pattern is projected in focus to improve measurement accuracy, then the light intensity distribution deviates from sinusoidal waveform, but measurement accuracy deteriorates
Solution Approach 1:
The patent replaces the mechanical defocusing method with a signal processing approach. Instead of physically defocusing the projection lens to achieve sinusoidal waveform, the system captures the rectangular waveform pattern and transforms it into sinusoidal waveform data through image processing algorithms. This substitution eliminates the need for mechanical defocusing while achieving the desired sinusoidal light intensity distribution for accurate phase shift measurement.
Solution Approach 2:
The patent changes the parameter of light intensity distribution from rectangular waveform to sinusoidal waveform through signal processing. By capturing the rectangular waveform pattern and applying mathematical transformations (such as Fourier transform or fitting algorithms), the system converts the parameter representation into sinusoidal waveform, thereby maintaining measurement accuracy without requiring physical defocusing.
2Manufacturing precision
If defocusing is used to achieve sinusoidal light intensity distribution, then waveform accuracy improves, but device complexity and difficulty of maintenance increase
Solution Approach 1:
The patent replaces the mechanical defocusing method with a signal processing approach. Instead of physically defocusing the projection lens to achieve sinusoidal waveform, the system captures the rectangular waveform pattern and transforms it into sinusoidal waveform data through image processing algorithms. This substitution eliminates the need for mechanical defocusing while achieving the desired sinusoidal light intensity distribution for accurate phase shift measurement.
3Manufacturing precision
If out-of-focus projection is used to obtain sinusoidal waveform, then light intensity distribution improves, but telecentric optical system capability is lost
Solution Approach 1:
The patent replaces the mechanical defocusing method with a signal processing approach. Instead of physically defocusing the projection lens to achieve sinusoidal waveform, the system captures the rectangular waveform pattern and transforms it into sinusoidal waveform data through image processing algorithms. This substitution eliminates the need for mechanical defocusing while achieving the desired sinusoidal light intensity distribution for accurate phase shift measurement.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration improves measurement accuracy by obtaining image data with a light intensity distribution closer to the ideal sinusoidal waveform, maintaining waveform integrity during focus projection, and reducing manufacturing costs by simplifying the mechanical setup.
Implementation Method 1
a recently proposed technique projects a striped pattern having a light intensity distribution in a rectangular waveform that is obtained by conversion via a grid, on a measurement object with defocusing, so as to project this striped pattern as a striped pattern having a light intensity distribution in a sinusoidal waveform
Implementation Method 2
The three-dimensional measurement device then uses an imaging unit placed immediately above the measurement object to take an image of the striped pattern projected on the measurement object
Data Source
AI summary
A three-dimensional measurement device includes: a projector including: a light source that emits a predetermined light; a grid that converts the light from the light source into a predetermined striped pattern; and a driver that moves the grid, and the projector projecting the striped pattern onto a measurement object; an imaging device that takes an image of the measurement object on which the striped pattern is projected; and a controller that: controls the projector and the imaging device to obtain a plurality of image data having different light intensity distributions; executes three-dimensional measurement of the measurement object by phase shifting based on the image data having different light intensity distributions; and obtains each of the image data among the image data having different light intensity distributions.