3D Shape Measurement Device Dual-Irradiation Grating Shift
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Solution Overview
Problem
Current three-dimensional shape measurement devices using the phase shift method face challenges in achieving accurate measurements due to shadowed parts and require lengthy measurement times, especially when using multiple light patterns and grating shifts.
Innovation Solution
A device that simultaneously irradiates light patterns from two directions with overlapping grating shift operations, allowing for concurrent imaging and grating shifting without waiting for completion of one operation, reducing the overall measurement time by overlapping the long grating shift intervals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single irradiation unit is used for three-dimensional shape measurement, then the device complexity is reduced, but shadowed parts occur where accurate measurement is not possible
Solution Approach 1:
The single irradiation unit is segmented into two separate irradiation units, each equipped with its own light source and grating. This segmentation allows light to be irradiated from multiple directions, eliminating shadowed areas and improving measurement accuracy without significantly increasing overall system complexity.
2Measurement precision
If two irradiation units are used to improve measurement accuracy by irradiating from two directions, then measurement precision is improved, but measurement time increases due to sequential grating shifting
Solution Approach 1:
The system implements continuous useful action by overlapping the grating shifting operations of the first and second irradiation units. While the first grating is being shifted, the second grating simultaneously performs its shifting operation. This parallel execution maintains high measurement precision while significantly reducing the total measurement time compared to sequential operations.
Solution Approach 2:
The gratings are pre-positioned at multiple phase positions, allowing the imaging unit to capture images at different phases without waiting for complete grating shifts. This preliminary preparation enables concurrent imaging operations to overlap with grating shifting operations, reducing idle time and accelerating the measurement process.
3Measurement precision
If grating shifting is performed sequentially for two irradiation units, then measurement precision is maintained, but productivity decreases due to long measurement time
Solution Approach 1:
The system maintains continuous useful action by overlapping the grating shifting operations of both irradiation units. The first grating shifts while the second grating simultaneously shifts, and imaging operations are performed during these shifts. This parallel processing maintains measurement precision while doubling the productivity compared to sequential operations.
4Measurement precision
If imaging is performed with short time intervals to reduce vibration effects, then measurement precision is improved, but the grating shifting cannot be completed in time
Solution Approach 1:
The gratings are pre-positioned at multiple phase positions (e.g., 0, π/2, π, 3π/2 phases) before imaging begins. This preliminary positioning allows the imaging unit to capture images at different phases without waiting for complete grating shifts, enabling short exposure times that reduce vibration effects while still obtaining all necessary phase information for accurate measurement.
Solution Approach 2:
The system dynamically coordinates the grating shifting and imaging operations, allowing imaging to occur during the shifting process rather than requiring completion. This dynamic approach enables short time intervals for imaging to capture vibration-free images while the gratings are in motion, maintaining measurement precision without being constrained by the full shifting duration.
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 significantly reduces the measurement time by approximately 44% compared to traditional methods, while improving measurement accuracy by minimizing shadowed areas and maintaining high precision over a wide dynamic range.
Implementation Method 1
uses an irradiation unit composed of a light source emitting a certain light and a grating for transformation of this light from the light source to a light pattern having a sinusoidal wave pattern (stripe-shaped pattern) to irradiate the light pattern on the object to be measured
Data Source
AI summary
A device for measuring three dimensional shape is configured to perform one of a first imaging operation as imaging processing of a single operation among a multiplicity of imaging operations performed by irradiation of a first light pattern of multiply varied phases, and a second imaging operation as imaging processing of a single operation among a multiplicity of imaging operations performed by irradiation of a second light pattern of multiply varied phases. The device is configured to, simultaneous with completion of the first or second imaging operation, start shifting or switching operation of said first grating or a second grating relating to said first imaging operation. The device is configured to, without waiting for completion of the shifting or switching operation, perform the other imaging operation from among the first and second imaging operations.