Glossy Surface Inspection Using Multi-Position Collimated Illumination
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Solution Overview
Problem
Existing inspection methods for glossy surfaces require time-consuming adjustments of optical axes and filter settings, leading to inefficiencies and reduced defect detection accuracy, particularly when dealing with diffuse reflectance and low-contrast defects.
Innovation Solution
An inspection system utilizing a light emitting device with adjustable light emission positions, a collimator lens, and an imaging device that generates analysis images based on pixel luminance changes across multiple captures, eliminating the need for precise optical axis alignment and filter adjustments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If parallel light coaxial illumination is used to inspect glossy surfaces, then defect detection capability is improved, but adjustment time and complexity increase due to requiring precise optical axis alignment
Solution Approach 1:
The illumination is segmented into multiple discrete light emission positions arranged in a matrix pattern, allowing selective activation of specific light sources rather than requiring precise alignment of a single parallel light beam. This segmentation enables flexible inspection of different surface regions without complex optical adjustments.
Solution Approach 2:
The matrix array of light emitting devices provides multi-functional capability by illuminating multiple positions and angles simultaneously, allowing the same system to inspect various surface characteristics (glossy, diffuse, irregular) without requiring separate illumination systems or complex alignment procedures for each case.
2Measurement precision
If reflection phase shift method is used to detect surface defects, then defect detection accuracy is improved, but performance deteriorates when diffuse reflectance is large due to decreased stripe contrast
Solution Approach 1:
Different regions of the matrix light emitting device array provide different illumination angles and intensities tailored to local surface characteristics. By selectively activating specific light sources in the matrix, the system adapts to local variations in surface reflectance properties, maintaining detection accuracy for both glossy and diffuse surfaces.
Solution Approach 2:
The system dynamically selects and activates specific light emitting positions from the matrix array based on the observed surface reflectance characteristics. This dynamic adaptation allows the illumination configuration to be optimized in real-time for the specific inspection scenario, overcoming the limitations of fixed illumination methods.
3Measurement precision
If inspection illumination apparatus with filter means is used to achieve uniform detection conditions, then defect detection consistency is improved, but adjustment complexity and time increase
Solution Approach 1:
The mechanical/optical filter means system is replaced with an electronically controllable matrix array of light emitting devices. Instead of physically adjusting filters and their positions, the system uses electronic control to selectively activate different light sources in the matrix, achieving uniform detection conditions through software control rather than mechanical adjustment.
Solution Approach 2:
The system changes illumination parameters (position, angle, intensity) by electronically controlling which light emitting devices in the matrix are activated. This parameter control replaces the need for physical filter adjustments, allowing rapid reconfiguration of illumination conditions to achieve consistent detection across 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
This approach reduces setup time and enhances defect detection accuracy by accurately representing surface normal directions and irregularities, even in the presence of diffuse reflections, without the need for complex optical adjustments.
Implementation Method 1
a collimator lens arranged between the light emitting device and the target object
Implementation Method 2
illuminate the target object with light from a plurality of light emission positions... imaging the target object
Data Source
AI summary
An inspection system includes: a light emitting device configured to illuminate a target object; a collimator lens arranged between the light emitting device and the target object; and an imaging device configured to image the target object. The light emitting device is capable of changing a light emission position. The inspection system further includes an image analysis unit configured to generate an analysis image in which a value of each pixel corresponds to a normal direction of a surface of the target object appearing in the pixel, by analyzing a plurality of captured images obtained individually from a plurality of times of imaging where the light emission positions are different from each other. As a result, time and effort in adjustment for inspection can be reduced, and defect detection accuracy is improved.