Automated Surface Inspection Sensor Using Multi-Modal Optical Scanning
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Solution Overview
Problem
Current methods for inspecting surface and structural defects are labor-intensive, prone to errors, and require significant maintenance time, necessitating a more efficient and accurate approach.
Innovation Solution
An automated inspection system utilizing multiple sensing modalities such as ring illumination angular scanning, coherent speckle scanning, multi-spectral imaging, and polarization detection, combined with wireless triangulation and ultrasonic distance measurements to create a digital map of defects on a 3D structure model.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If automated inspection system with multiple sensing modalities is implemented, then defect detection accuracy is improved, but device complexity increases
Solution Approach 1:
The inspection system is divided into four independent sensing modalities (ring illumination angular scanning, coherent speckle scanning, multi-spectral imaging, and polarization detection), each targeting specific defect types. This segmentation allows the system to achieve high detection accuracy through specialized sensors while managing complexity by modularizing the inspection functions.
Solution Approach 2:
The sensor head integrates multiple sensing modalities into a single universal inspection device that can detect various defect types (coating defects, substrate defects, surface finish variations) across different material layers. This multi-functionality approach consolidates what would otherwise require separate inspection systems, balancing enhanced detection capability with manageable device complexity.
2Measurement precision
If multiple sensing modalities are used, then defect detection accuracy is improved, but inspection time increases
Solution Approach 1:
The system employs sequential activation of different sensing modalities during inspection, where each modality (ring illumination, coherent speckle, multi-spectral, polarization) is activated in periodic cycles. This allows comprehensive defect detection across multiple parameters while maintaining efficient inspection throughput by systematically rotating through detection modes rather than operating all simultaneously.
Solution Approach 2:
The system performs preliminary scanning using faster modalities (such as multi-spectral imaging) to identify potential defect locations, then applies more time-consuming specialized modalities (such as coherent speckle scanning for micro-pits) only to suspicious areas. This staged approach maintains high detection accuracy while minimizing overall inspection time by avoiding exhaustive full-surface analysis with all modalities.
3Measurement precision
If ring illumination angular scanning is used, then defect detection accuracy is improved, but ease of operation decreases
Solution Approach 1:
The ring illumination system automatically adjusts the angular scanning parameters and illumination intensity based on the detected surface properties and defect characteristics. The system self-regulates the inspection process without requiring manual calibration or adjustment by the operator, thereby maintaining high detection accuracy while simplifying operation through automated adaptation to different inspection scenarios.
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 system drastically reduces inspection time, enhances defect detection accuracy, and enables precise location mapping of defects, facilitating efficient maintenance and quality assurance.
Implementation Method 1
ring illumination angular scanning (i) reveals defects were either part of, or the entire coating is removed, because reflectivity will have a different angular directionality
Implementation Method 2
coherent speckle scanning (ii) measures micro-pits, voids, small/pinhole defects, cracks, and discontinuities on the surface of a coating and structure
Implementation Method 3
Multi-spectral (UV, visible and IR) imaging (iii) is used for multi-material assessment to distinguish between defects at different material layers
Implementation Method 4
differential polarization detection reveals defects by detecting a variation in the surface finish such as the coating and the structure body
Implementation Method 5
ultrasonic distance measurements
Data Source
AI summary
Various surface and structural defects are currently inspected visually. This method is labor intensive, requiring large maintenance man hours, and is prone to errors. To streamline this process, herein is described an automated inspection system and apparatus based on several optical technologies that drastically reduces inspection time, provides accurate detection of defects, and provides a digital map of the location of defects. The technology uses a sensor that includes a pattern projection generator for generating a pattern image on the structural surface and a camera for detecting the pattern image generated by the pattern projection generator on the structural surface. Furthermore, the technology utilizes an image processing and correction apparatus for performing a pattern image and structural surface defect map correction and generate a distortion corrected defect map for a surface scan area on the structure that is incident on the sensor.