Optical Component Defect Detection via Phase-Amplitude Image Analysis
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Solution Overview
Problem
Current methods for detecting defects in optical components, such as lenses, are inefficient, unreliable, and costly due to reliance on visual inspection and complex calibration procedures, often leading to prolonged measurement times and incorrect classification of defects.
Innovation Solution
A method and apparatus that utilize image processing techniques to capture and analyze reflected or transmitted images of optical components, merging phase and amplitude data to differentiate between defects and dust, allowing for automatic classification and rejection of defective lenses without prior cleaning, using adaptive filtering and B-spline interpolation to enhance image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If visual inspection by trained personnel is used, then defect detection can be performed, but the process is expensive, not sufficiently objective, and not sufficiently reliable
Solution Approach 1:
The patent replaces manual visual inspection with an automated optical inspection system that captures images of the optical component, processes them through algorithms, and automatically detects defects. This substitution eliminates human subjectivity and variability while providing consistent, objective, and reliable defect detection without requiring complex manual procedures
Solution Approach 2:
The system creates a digital copy (image) of the optical component's surface and bulk, then analyzes this copy through image processing algorithms to detect defects. This allows multiple analyses of the same component without physical contact or complex manipulation, improving reliability while keeping the inspection system relatively simple
2Measurement precision
If conventional testing methods are used, then defect detection is performed, but measurement time is long to obtain a reliable result and dramatically slows the control process
Solution Approach 1:
The patent uses periodic phase-shifting interference patterns to capture multiple images at different phase states. By systematically varying the phase and capturing images at regular intervals, the system efficiently extracts both amplitude and phase information in a structured sequence, achieving high measurement precision while minimizing total measurement time through optimized periodic sampling
Solution Approach 2:
The system performs preliminary calibration by capturing images of a reference optical component without defects to establish baseline phase and amplitude values. This preliminary action creates reference data that speeds up subsequent defect detection by allowing direct comparison rather than requiring full measurement procedures for each component, reducing measurement time while maintaining precision
3Reliability
If conventional testing methods are used, then defect detection is attempted, but type of defects cannot be classified properly and good samples may be rejected
Solution Approach 1:
The patent segments the defect analysis into distinct processing stages: image capture, phase extraction, amplitude extraction, defect detection, and classification. By dividing the complex classification task into sequential segments, each handling a specific aspect (surface defects vs. bulk defects, cosmetic vs. structural), the system achieves high classification accuracy while keeping each individual processing step relatively simple and manageable
Solution Approach 2:
The system applies different analysis methods and criteria to different regions and types of defects. Surface defects are analyzed using phase information, while bulk defects use amplitude information. Cosmetic defects have different acceptance criteria than structural defects. This localized quality approach enables proper classification accuracy without requiring a single overly complex universal classification system
4Reliability
If conventional testing methods are used, then defect inspection is performed, but expensive devices are required for carrying out the test method
Solution Approach 1:
The patent employs a single optical setup that can detect both surface defects and bulk defects, classify different defect types, and inspect various optical component types. By making the inspection system universal and multi-functional, it eliminates the need for multiple specialized expensive devices, achieving high inspection reliability while reducing overall system cost through consolidation of functions into one apparatus
5Measurement precision
If conventional testing methods are used, then defect detection is performed, but the test method needs complex standardization or calibration procedures
Solution Approach 1:
The system performs preliminary calibration by capturing images of a reference optical component without defects to establish baseline phase and amplitude values. This preliminary calibration action creates reference data that simplifies subsequent measurements, allowing direct comparison and automatic defect detection without requiring complex standardization procedures for each new component, thus maintaining measurement accuracy while reducing procedural complexity
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 rapid, reliable, and cost-effective inspection of optical components, accurately distinguishing between defects and dust, and is applicable to various lens types, including progressive addition lenses, without the need for expensive equipment or complex standardization.
Implementation Method 1
A method and apparatus for detecting defects in optical components such as lenses, particularly cosmetic defects consisting of surface flaws and occlusions
Implementation Method 2
Both reflected or transmitted image capture and treatment are possible
Data Source
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Figure 2
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AI summary
A method for detecting defects in an optical component to be tested, such as a lens comprising following steps : providing a structured pattern, recording the reflected or transmitted image (21) of the pattern on the optical component to be tested, phase shifting the pattern and recording again similarly the reflected or transmitted image, calculating the local phase and amplitude images of the optical component to be tested, calculating a model image (212) of a defect free optical component and determining corresponding phase and amplitude images of the defect free model optical component, comparing (26) phase and amplitude images of both optical component to be tested and defect free model optical component, determining suspect zones (27) in the optical component to be tested, applying a metrics (28) to separate dust and noise from other defects. Related device and computer program. Use of said method to apply a selection method to a set of optical components.