3D Measurement Device Phase Shift Luminance Extraction
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Solution Overview
Problem
Conventional three-dimensional measurement devices using the phase shift method require multiple irradiation and imaging steps with different light patterns, leading to increased measurement time, especially when dealing with large numbers of measurement objects on a printed circuit board, as they need to adjust for overexposed or underexposed luminance values.
Innovation Solution
A three-dimensional measurement device that shifts the phase of the light pattern in multiple ways and extracts relevant luminance values that are neither overexposed nor underexposed, allowing for height measurement using these values, thereby expanding the luminance dynamic range and reducing the need for multiple measurement sets.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple irradiation and imaging steps with different light patterns are performed to handle overexposed or underexposed luminance values, then measurement accuracy is improved, but measurement time increases
Solution Approach 1:
The patent segments the N luminance values obtained from phase-shifted images and selectively uses only those values that fall within the valid luminance range (neither overexposed nor underexposed). This segmentation approach allows the system to discard invalid data points while utilizing valid ones, thereby maintaining measurement accuracy without requiring multiple complete measurement cycles.
Solution Approach 2:
The patent performs preliminary extraction and validation of luminance values from the N phase-shifted images before proceeding to height calculation. By预先 identifying and selecting only the valid luminance values (those neither overexposed nor underexposed), the system prepares a clean dataset for accurate measurement without needing to repeat the entire imaging process, thus reducing measurement time while preserving accuracy.
2Reliability
If two different light patterns with different luminances are used to perform three-dimensional measurement, then measurement reliability is improved, but device complexity increases
Solution Approach 1:
The patent makes the single light pattern multi-functional by using it in N different phase-shifted configurations. Instead of requiring multiple light patterns with different luminances, the system achieves equivalent reliability by varying the phase of a single light pattern across N steps, allowing one light source to serve multiple measurement purposes.
Solution Approach 2:
The patent changes the phase parameter of the light pattern across N different measurements rather than changing the luminance parameter by using multiple light sources. This parameter substitution maintains measurement reliability through diverse data collection while avoiding the complexity of multiple light sources with different luminances.
3Loss of information
If N different image data are obtained by shifting phase in N different ways, then data completeness is improved, but processing complexity increases
Solution Approach 1:
The patent extracts only the valid luminance values from the N image data based on predetermined criteria (whether values are within the acceptable range). This extraction process separates useful information from invalid data, ensuring data completeness for valid regions while simplifying processing by excluding overexposed and underexposed values from further calculation.
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 approach enables high-speed three-dimensional measurement with improved accuracy by using multiple luminance values that are neither overexposed nor underexposed, reducing measurement time and enhancing data completeness.
Implementation Method 1
a grating that converts the light from the light source into a light pattern having a light intensity distribution in a sinusoidal shape (fringe shape)
Implementation Method 2
a single-plate color image sensor is generally used as the imaging element, and one of color filters of red (R), green (G) and blue (B) having different imageable wavelength regions is placed in each pixel of the imaging element
Data Source
AI summary
A three-dimensional measurement device performs three-dimensional measurement of a measured object using a phase shift method. The three-dimensional measurement device includes: an irradiator that irradiates the measured object with a predetermined light pattern having a light intensity distribution in a fringe shape; a control device that shifts a phase of the light pattern radiated from the irradiator in N different ways, where N is a natural number of not less than 3; and an imaging device that takes an image of the measured object irradiated with the light pattern. The control device executes three-dimensional measurement of the measured object by the phase shift method based on N different image data taken under the light pattern having the phase shifted in the N different ways.