Surface Inspection System Differentiating Contamination from Defects
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Solution Overview
Problem
Conventional surface inspection systems using phase-shifted deflectometry struggle to differentiate particulate contamination from actual defects, often falsely recognizing dust or particles as defects, leading to high overkill rates and complex evaluation tuning challenges.
Innovation Solution
The system collects both PSD image data and additional dust channel image data by illuminating the specimen at a predetermined angle, using a controller to correlate and separate defect and contamination information, reducing false positives and improving differentiation between defects and contamination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If phase-shifted deflectometry is used for surface inspection, then sensitivity to surface changes is improved, but differentiation between particulate contamination and defects deteriorates
Solution Approach 1:
The inspection system segments the analysis by creating separate evaluation channels: a PSD channel for surface defect detection and a dust channel for particulate contamination detection. This segmentation allows independent optimization and evaluation of each channel, enabling reliable differentiation between contamination and defects while maintaining high sensitivity through PSD.
Solution Approach 2:
The patent introduces an intermediary dust channel that acts as a mediator between the illumination source and the evaluation process. This dust channel specifically captures particulate contamination, serving as an intermediary step that separates contamination information from defect information before final evaluation, thereby improving differentiation reliability.
2Productivity
If conventional PSD setup is used, then inspection throughput is maintained, but false recognition of particles as defects increases
Solution Approach 1:
The system merges the PSD inspection channel and the dust channel into a unified evaluation process. Both channels operate simultaneously during inspection, combining their respective strengths: PSD provides high-speed surface analysis while the dust channel provides contamination filtering. This merging maintains productivity while improving measurement precision through complementary information.
Solution Approach 2:
The illumination source and imaging system perform multiple functions: they simultaneously generate PSD patterns for surface defect detection and create dust channel images for contamination identification. This multi-functionality allows the system to maintain high throughput while accurately differentiating between particles and defects without requiring separate inspection passes.
3Reliability
If deep learning algorithms are employed to separate contamination from defects, then differentiation performance is moderately improved, but system complexity and tuning requirements increase
Solution Approach 1:
The patent replaces complex deep learning algorithms with a simpler optical-mechanical solution: a dedicated dust channel with specific illumination geometry. Instead of using complex computational methods to separate contamination from defects, the system uses a straightforward additional imaging channel that physically separates the information streams, significantly reducing algorithmic complexity while maintaining reliable differentiation.
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 effectively reduces overkill rates by providing additional information channels, allowing for more accurate identification and location of defects and contamination, enhancing the reliability of automated inspection processes.
Implementation Method 1
an illumination source configured to illuminate the specimen with a light at a predetermined angle relative to the surface of the specimen
Data Source
AI summary
A system for differentiating particulate contamination from defects on a surface of a specimen includes an illumination source configured to illuminate the specimen with a light at a predetermined angle relative to the surface of the specimen, an image recording device configured to capture the light reflected from the surface of the specimen in a sensor image, and an evaluation unit configured to receive deflectometry or phase-shifted deflectometry (PSD) image data and dust channel image data from the image recording device, correlate the PSD image data and dust channel image data, and separately output first result information and second result information, the first result information including defect identification information and defect location information and the second result information including contamination identification information and contamination location information.