Bore Testing Device Multi-Directional Illumination Shadow Imaging
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Solution Overview
Problem
Existing bore testing devices are inadequate in detecting surface defects and differentiating between surface anomalies, particularly in determining the depth of defects and reducing faulty detections due to soiling.
Innovation Solution
A bore testing device with an optical system and illumination arrangement that generates shadow images by illuminating the inner surface from multiple directions, using the 'shape from shading' method for topography evaluation, allowing for accurate detection of surface defects and differentiating between elevations and depressions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional single-direction illumination is used, then the device structure is simple, but surface defects such as depressions cannot be accurately detected and differentiated
Solution Approach 1:
The illumination arrangement is segmented into multiple independent light source arrangements, each positioned to provide illumination from a specific direction. This segmentation allows the system to capture shadow images from multiple angles, enabling accurate detection of surface defects like depressions while maintaining modular simplicity in each individual light source unit.
Solution Approach 2:
The illumination system transitions from single-direction (one-dimensional) illumination to multi-directional (three-dimensional) illumination by positioning light sources at different spatial locations. This dimensional expansion creates shadow images that reveal topographic information, allowing the system to detect surface defects with depth information that conventional single-direction illumination cannot provide.
2Loss of information
If multiple illumination directions are used to generate shadow images, then topography information can be determined, but the number of light sources and device complexity increases
Solution Approach 1:
The system performs preliminary action by strategically positioning light source arrangements before measurement to ensure optimal shadow image capture. The light sources are pre-positioned at specific angles and locations that maximize topographic information retrieval, allowing the evaluation apparatus to accurately determine surface depth information without requiring an excessive number of light sources.
Solution Approach 2:
The shadow images serve as an intermediary that translates three-dimensional surface topography into two-dimensional image data. This intermediary representation allows the evaluation apparatus to extract depth information and differentiate surface defects without requiring direct physical contact with the surface or an overly complex measurement system.
3Reliability
If conventional illumination is used, then the device is compact, but faulty detections occur due to surface soiling and inability to differentiate defect types
Solution Approach 1:
The system implements feedback through the evaluation apparatus that analyzes shadow images from multiple illumination directions. By comparing shadow patterns from different angles, the system can distinguish between actual surface defects and artifacts caused by soiling, significantly improving detection reliability. The feedback loop allows the system to validate findings across multiple illumination perspectives before confirming a defect.
Solution Approach 2:
The shadow images exhibit varying intensity and contrast patterns (analogous to color changes) depending on the illumination direction and surface topography. Defects such as depressions create characteristic shadow patterns that differ from soiling artifacts, allowing the evaluation apparatus to differentiate between defect types based on these optical response variations across multiple illumination conditions.
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
Enables precise detection of surface defects, reduces faulty detections, and provides depth information, improving the assessment of inner surface quality with a compact and efficient design.
Implementation Method 1
The illumination arrangement is configured for illuminating the inner surface to be tested from different illumination directions in order to generate shadow images of the topography of the inner surface
Data Source
AI summary
A testing device for testing an inner surface of a rotationally symmetrical cavity in a workpiece has a measuring head which defines an axial direction, and on which an optical system is situated. The optical system is in image transmission connection with an image recorder and a downstream evaluation apparatus. The testing device also has an illumination arrangement for illuminating an imaging area of the inner surface which is detected by the optical system. The illumination arrangement is designed and configured for illuminating the inner surface which is detected by the optical system. The illumination arrangement can illuminate the inner surface to be tested from different illumination directions in order to generate shadow images of the topography of the inner surface. The evaluation apparatus is designed and configured for determining the topography based on the shadow images recorded by the image recorder.