Contoured Surface Illumination for Shallow Defect Inspection
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Solution Overview
Problem
Existing inspection and illumination systems for jet engine parts struggle to capture shallow geometric defects due to the orientation of the light source relative to the contoured surface, leading to inadequate image contrast and difficulty in identifying defects, particularly when using line scan cameras.
Innovation Solution
The system employs a surface profile compensator that adjusts the light distribution over the contoured surface by shaping the light source to match the 3D surface profile, altering illumination densities, and varying the illumination direction to enhance image contrast, using a combination of passive and active deformation of the support structure and light intensity control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the light source is positioned normal to the surface near the camera, then the inspection system is simple to operate, but shallow geometric defects cannot be captured due to inadequate image contrast
Solution Approach 1:
The illumination system uses multiple light sources positioned at different angles relative to the camera axis, with each light source providing localized illumination from a specific direction. This allows different regions of the contoured surface to be illuminated optimally for detecting various types of defects, resolving the contradiction between operational simplicity and measurement precision.
Solution Approach 2:
The patent transitions from single-directional illumination (normal to surface) to multi-directional illumination by positioning light sources at different angular positions. This dimensional change in illumination approach enables the system to capture shallow geometric defects that would be invisible with normal illumination, improving measurement precision while maintaining ease of operation through automated multi-angle imaging.
2Device complexity
If a bar-style light source is used, then the device complexity is reduced, but high divergent contrast is created due to distance variation from the light source to the 3D surface
Solution Approach 1:
The illumination system is segmented into multiple independent light sources rather than using a single bar-style source. Each light source can be independently positioned and controlled, allowing the system to maintain simple device architecture while eliminating the divergent contrast problem by providing more uniform illumination across the contoured surface through strategic positioning.
Solution Approach 2:
The patent employs asymmetric positioning of light sources relative to the camera and workpiece, with light sources placed at specific angular positions that are not symmetrically equivalent. This asymmetric arrangement optimizes illumination uniformity across the 3D surface, reducing distance variation effects and improving reliability without significantly increasing device complexity.
3Ease of manufacture
If the light source orientation is normal to the surface, then the illumination system is simple to implement, but image contrast on geometric defects is insufficient for effective defect detection
Solution Approach 1:
The illumination system incorporates dynamic positioning of light sources at multiple angular positions, allowing the illumination direction to be varied to optimize contrast for different defect types and surface geometries. This dynamic approach maintains ease of manufacture through standardized components while preventing information loss about shallow geometric defects through multi-angle imaging.
Solution Approach 2:
The patent creates a universal illumination system that can detect multiple types of defects (shallow geometric defects, surface cracks, coating defects) using the same multi-angle light source configuration. This multi-functional approach ensures comprehensive defect detection without losing information about various defect types, while maintaining ease of manufacture through a standardized multi-source platform.
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 improves image contrast on geometric defects, allowing for better defect detection on 3D contoured surfaces by ensuring uniform or targeted light distribution, thereby enhancing the inspection process.
Implementation Method 1
The support structure may be formed from a pliable material that conforms in part to a shape of the contoured surface when the support structure contacts the contoured surface
Implementation Method 2
The inspection system may include one or more actuators that actively deform the support structure to complement the contours of the contoured surface
Implementation Method 3
The controller acts as the surface profile compensator by adjusting an intensity of the light source at different locations to distribute the light over the inspection area according to the target light distribution
Data Source
AI summary
An inspection system is provided. The inspection system includes a light source and a surface profile compensator. The light source illuminates a contoured surface of a part. The surface profile compensator causes light emitted from the light source to be distributed over an inspection area of the contoured surface according to a target light distribution.