Surface defect detection device and method based on polarized optical dark field imaging

Through polarization optical dark field imaging technology, a polarization camera and LED light source are used to obtain polarization images, calculate the low-frequency linear polarization degree map and combine it with filtering and noise reduction to invert the defect depth. This solves the problems of complex equipment and high cost in traditional methods and realizes fast and sensitive defect depth detection.

CN120741480AActive Publication Date: 2025-10-03UNIV OF SCI & TECH OF CHINA
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Patent Information

Application Number
CN202511166507.9
Authority / Receiving Office
CN · China
Patent Type
Applications(China)
Current Assignee / Owner
Filing Date
2025-08-20
Publication Date
2025-10-03
Estimated Expiration
2045-08-20

AI Technical Summary

Technical Problem

Existing technologies cannot achieve rapid and highly sensitive analysis of surface defect depth without the need for complex optical components and precision scanning. Traditional methods and equipment are large, complex, and costly, making them difficult to adapt to the high-speed, large-scale inspection needs of industrial assembly lines.

Method used

A coaxially arranged polarization camera, imaging lens, and polarized circular LED light source are used to acquire polarization images through reflective dark-field illumination. The low-frequency linear polarization degree map is calculated and combined with three-dimensional block matching noise reduction filtering to invert the defect depth. The high- and low-frequency linear polarization degree maps are weightedly fused to achieve adaptation to multiple detection standards.

Benefits of technology

It achieves fast and highly sensitive detection of defect depth, reduces equipment costs, is suitable for industrial low-cost detection, and has high robustness and high-speed detection capabilities.

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Abstract

The invention discloses a surface defect detection device and method based on polarized optical dark field imaging, and belongs to the technical field of industrial defect imaging detection, the device comprises a polarization camera, an imaging lens, a polarization annular LED light source and a sample to be detected which are coaxially arranged; wherein the polarization camera and the imaging lens form a polarization imaging system, the polarization annular LED light source emits linearly polarized light with an inclination angle, and the linearly polarized light is reflected and scattered on a sample to be detected; the linearly polarized light enters the surface of a to-be-detected sample, a small amount of reflection and most of scattered light of the to-be-detected sample are collected by the imaging lens and the polarization camera through a circular hole in the center of the polarization annular LED light source, and finally imaging is achieved. The defect depth can be calculated according to the defect width and the defect inclination angle, so that the defect depth is inversed by the low-frequency linear polarization degree, and the problem that the defect depth information cannot be effectively extracted in the prior art is solved.
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