Multi-Frequency Point Cloud Metrology for Unambiguous Precision
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Solution Overview
Problem
Existing metrology systems face challenges in generating accurate point clouds when objects are positioned outside the unambiguous range of an optical sensor, leading to decreased measurement precision and ambiguity in distance measurements.
Innovation Solution
A metrology system uses multiple frequencies to generate a first coarse point cloud and a second fine point cloud, determining relative depth measurements from the first point cloud to the second, and generating a corrected third point cloud with improved precision by compensating for the shorter unambiguous range of the second frequency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a higher frequency is used to generate the second point cloud, then measurement precision is improved, but the unambiguous range becomes shorter causing ambiguity when objects are outside the range
Solution Approach 1:
The measurement process is segmented into two stages: first using a lower frequency to establish the unambiguous range and identify the correct fringe order, then using a higher frequency to achieve precise distance measurements. This segmentation allows each frequency to be optimized for its specific purpose without the limitations of using a single frequency.
Solution Approach 2:
The lower frequency measurement acts as an intermediary that provides the fringe order information needed to interpret the higher frequency measurements. This intermediary step resolves the ambiguity that would otherwise prevent reliable high-precision measurements of objects outside the unambiguous range.
2Device complexity
If a single frequency is used for point cloud generation, then the system complexity is reduced, but measurement precision and unambiguous range cannot be simultaneously optimized
Solution Approach 1:
The metrology system achieves multi-functionality by using multiple frequencies with the same optical sensor hardware. The system can switch between different measurement modes (low frequency for unambiguous range, high frequency for precision) without requiring separate physical devices, thereby maintaining relatively simple device architecture while achieving multiple measurement objectives.
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
The method enhances measurement precision and reduces ambiguity by generating a third point cloud with improved accuracy and resolution, enabling accurate distance measurements even when objects are outside the unambiguous range of the optical sensor.
Implementation Method 1
Each point of the first point cloud indicates a distance measurement from a portion of the region of the object to an optical sensor of the metrology system
Data Source
AI summary
A metrology system may generate, using a first frequency, a first point cloud associated with a region of an object and may identify a particular distance measurement associated with a particular point of the first point cloud. The metrology system may generate, using a second frequency that is greater than the first frequency, a second point cloud associated with the region of the object. The metrology system may determine one or more relative depth measurements from the particular point of the first point cloud to one or more points of the second point cloud, respectively. The metrology system may thereby generate a third point cloud associated with the region of the object to include one or more points that correspond to the one or more points of the second point cloud and that indicate the one or more relative depth measurements, respectively.