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A New Stitching Method for Dark-Field Surface Defects Inspection Based on Simplified Target-Tracking and Path
Xue Chen1,2,3, Jiaqi Li1,2,3, Yongxin Sui1,3
1Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun 130033, China.
Sensors (Basel, Switzerland)
|January 17, 2020
Summary
This study introduces a new stitching method for dark-field imaging systems, improving defect detection on large optics. The technique reduces mismatches and location errors, enhancing the identification of even weak defects.
Area of Science:
- Optical Engineering
- Metrology
- Surface Science
Background:
- Camera-based dark-field imaging systems detect micron-scale defects on large optics via scanning and stitching.
- Conventional stitching methods struggle with mismatches and location deviations due to sparse defect distribution.
Purpose of the Study:
- To develop a highly efficient stitching method for dark-field imaging systems.
- To overcome limitations of conventional stitching, specifically mismatches and location deviations.
- To enhance the detectability of micron-scale defects on large optical surfaces.
Main Methods:
- Proposed a simplified target-tracking and adaptive scanning path correction method.
- Treated defects as moving targets by increasing sub-apertures and switching camera perspective.
- Implemented target tracking for marked targets and corrected scanning paths by minimizing deviations.
- Updated final stitching results using the target-tracking method.
Main Results:
- Successfully identified 118 out of 120 defects on a specially designed testing sample.
- Achieved defect detection without stitching mismatches.
- Demonstrated reduction in mismatches and location deviations.
- Showcased increased detectability for weak defects.
Conclusions:
- The proposed target-tracking and adaptive scanning path correction method significantly improves stitching accuracy in dark-field imaging.
- This approach effectively minimizes mismatches and location deviations, crucial for defect detection on large optics.
- The method enhances the overall detectability of micron-scale defects, including subtle ones.
