Triangulation Imager Polarization Filter Segmentation
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Solution Overview
Problem
Light line triangulation apparatuses face difficulties in accurately determining the contour of measurement objects due to direct reflections that saturate or misproject light onto the imager, making line analysis challenging or impossible.
Innovation Solution
The apparatus employs multiple sets of polarization filters with different polarization directions across the imager's columns, allowing differentiation between direct and diffuse reflections, and an evaluation unit combines pixel values to determine the true position of the light line, effectively disregarding false signals from direct reflections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single polarization filter is used for the whole imager, then the device complexity is reduced, but the measurement precision deteriorates because it cannot handle unknown measurement objects with varying polarization characteristics
Solution Approach 1:
The imager is divided into multiple columns, with each column equipped with its own polarization filter. This segmentation allows different regions of the imager to capture light with different polarization states, enabling the system to handle unknown measurement objects while maintaining manageable device complexity through modular filter arrangement
Solution Approach 2:
The multiple polarization filters are configured to handle various measurement objects with unknown polarization characteristics. By providing multiple polarization filtering options across columns, the system becomes universally applicable to different object types without requiring prior knowledge of their specific polarization properties
2Measurement precision
If polarization filters are placed over individual pixels, then the measurement precision is improved, but the device complexity increases due to the need for multiple filters across columns
Solution Approach 1:
Different polarization filters are assigned to different columns based on local requirements. Each column receives a polarization filter suited for detecting specific reflection characteristics in that region, optimizing local measurement quality while maintaining overall system functionality
Solution Approach 2:
The polarization filtering is extended from a single-plane approach to a multi-column dimensional arrangement. By distributing polarization filters across multiple columns rather than using a single filter for all pixels, the system adds a spatial dimension to polarization detection, improving precision without overwhelming complexity
3Device complexity
If the imager is positioned at a smaller angle from the light projector, then the device complexity is reduced, but direct reflections increase causing pixel saturation and reducing measurement precision
Solution Approach 1:
Polarization filters serve as intermediary elements between the light projector and the measurement object. By introducing these filters, the system can distinguish between direct reflections (which have specific polarization characteristics) and diffuse reflections, thereby mitigating the harmful effects of direct reflections even when the imager is positioned at smaller angles
Solution Approach 2:
The system changes the polarization parameter of the detected light by using multiple polarization filters at different orientations. This parameter change allows the system to filter out direct reflections based on their polarization characteristics, reducing their harmful impact while maintaining a simpler imager positioning configuration
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 accurate contour detection of unknown measurement objects by distinguishing between direct and diffuse reflections, improving the accuracy of height measurements and contour determination without sacrificing resolution.
Implementation Method 1
The measurement object reflects the light from the light projector wherein the light reflected by the measurement object is detected by the imager
Implementation Method 2
The invention is based on the insight that unwanted direct reflections (i.e. specular reflections) can be differentiated from the usually detected diffuse reflections by their polarization
Data Source
AI summary
The present invention relates to a light line triangulation apparatus witha measurement space for receiving a measurement object,a light projector, adapted to project a light line into the measurement space and/or onto the measurement object,an imager for detecting the light line in the measurement space, wherein the imager comprises imaging pixels arranged in a plurality of columns and rows. The apparatus of the invention is characterized in that the imager comprises multiple identical sets of polarization filters, wherein each set of polarization filters comprises at least two polarization filters with different polarization directions, wherein a respective polarization filter covers one of the columns.