Photothermal Defect Detection in Solid Parts Using Reference Images
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Solution Overview
Problem
Existing photothermal analysis methods require scanning a surface portion of a piece twice in opposite directions, leading to long analysis cycle times and reduced production rates.
Innovation Solution
A method that uses a single analysis image per detection region, employing a reference image based on thermal emission distribution without defects, allowing for a single scan and significantly reducing cycle time, and a photothermal analysis assembly to implement this method.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the surface portion is scanned twice in opposite directions to obtain analysis images for defect detection, then the defect detection reliability is improved, but the analysis cycle time is doubled
Solution Approach 1:
A reference image showing the thermal emission distribution without defects is obtained in advance through simulation or measurement on a defect-free sample. This reference image is then reused across multiple detection regions and scanning passes, eliminating the need to capture and process reference data during each actual inspection, thereby reducing cycle time while maintaining detection reliability
Solution Approach 2:
The reference image obtained from a defect-free sample or simulation is copied and applied to multiple detection regions throughout the scanning process. Instead of capturing new reference images during each scan, the same reference data is reused to subtract from analysis images, significantly reducing the time required for reference image acquisition while preserving defect detection capability
2Measurement precision
If multiple analysis images are captured and processed to improve signal-to-noise ratio, then the measurement precision is improved, but the analysis cycle time increases
Solution Approach 1:
The reference image is obtained in advance through simulation or measurement on a defect-free sample, allowing the actual inspection to proceed with only analysis image capture and subtraction processing. This preliminary acquisition of reference data separates the reference generation from the inspection timing, reducing cycle time while maintaining the precision benefits of image subtraction
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
The method achieves a cycle time reduction by half and improves signal-to-noise ratio, enabling efficient defect detection in larger surface portions with enhanced sensitivity and reduced noise.
Implementation Method 1
injecting heat into a first region of the surface portion of the piece, called heating region, then, after a period during which some of the injected heat has diffused into another region of the surface portion of the piece
Implementation Method 2
capturing at least one thermal image, called analysis image, of the detection region
Implementation Method 3
subtracting a reference image from the analysis image, at least for a portion of the analysis image which corresponds to the detection region, in order to obtain a revealing image which shows at least one defect present in this detection region
Data Source
AI summary
A method of photothermal analysis of a solid piece includes injecting heat into a region of a surface of the piece, called heating region, capturing a thermal analysis image of a detection region which is distinct from the heating region, then subtracting a reference image from the thermal analysis image. The reference image corresponds to a thermal emission distribution as caused by the injected heat for a case where the surface portion of the piece is without defects. Such method makes it possible to reduce an analysis cycle time for the piece, and to reduce a signal-to-noise ratio of images capable of revealing defects present in the surface portion of the piece.