3D Shape Measuring Apparatus Micro-Displacement Stage
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing three-dimensional shape measuring apparatuses face limitations in achieving measurement accuracy beyond the physical resolution of the measuring-light illuminating device, particularly when dealing with long measurement objects that cannot be held on a rotatable stage.
Innovation Solution
A three-dimensional shape measuring apparatus that includes a translation stage, independently controllable two-dimensionally arranged projection devices, and a movement controller to translate the stage by a pitch smaller than the minimum projection pattern width, allowing for improved measurement accuracy by shifting the projection pattern micro-displacements and generating point cloud data using phase shift methods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If a translational stage is added to measure long objects, then the measurement range is improved, but the measurement accuracy is limited by the physical resolution of the projection device
Solution Approach 1:
The projection pattern is divided into multiple segments by translating the stage in small increments. Each translation step creates a slightly shifted projection pattern, and by combining data from multiple segments, the system achieves measurement accuracy finer than the original projection device resolution.
Solution Approach 2:
The system adds the translation dimension to the existing projection system. By moving the stage along the translation axis and capturing projection patterns at different positions, the system creates additional measurement data dimensions that enable super-resolution measurement beyond the original device capabilities.
2Measurement precision
If the projection pattern is shifted by micro-displacements, then the measurement accuracy is improved, but the stage translation precision is required to be very high
Solution Approach 1:
The system uses feedback from the captured projection pattern images to determine the actual phase shift amount. By analyzing the displacement of light and dark peaks in the projection patterns, the system can accurately measure the phase shift even if the stage translation has some error, and use this information to correct and improve measurement accuracy.
Solution Approach 2:
The system changes the parameter being measured from absolute position to relative phase shift. Instead of relying on absolute stage position accuracy, the system measures the relative shift between consecutive projection patterns, which can be determined with high precision through image processing and peak detection algorithms.
3Measurement precision
If phase shift method is used to improve accuracy, then the measurement precision is improved, but the number of projection patterns required increases
Solution Approach 1:
The system uses a minimal number of projection patterns (just two sets: before and after translation) to achieve the phase shift measurement. Instead of using multiple complex phase-shifted patterns traditionally required, the system captures projection patterns at two stage positions and computationally extracts the phase information, reducing the number of required measurements.
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 solution enhances measurement accuracy to a physical spatial resolution smaller than the projection patterns' physical resolution, enabling precise three-dimensional shape measurement without hardware improvements to the projection device.
Implementation Method 1
a photoreceptor that receives measuring light reflected by the measurement object illuminated by the illuminator, and to generate a projection pattern image
Data Source
AI summary
A three-dimensional shape measuring apparatus includes a stage that includes a translation stage part having a placement surface on which a measurement object is placed and capable of translating the placement surface; an illuminator that includes independently controllable and two-dimensionally-arranged projection devices, and illuminates the measurement object, which is placed on the stage, with measuring light having a predetermined projection pattern having alternating light-and-dark intervals; a photoreceptor that receives measuring light reflected by the measurement object illuminated by the illuminator, and to generate a projection pattern image; and a movement controller that controls the translational movement of the translation stage part by a moving pitch smaller than the minimum width of the projection pattern which can be projected on the stage by independently controlling the projection devices of the illuminator.