Ultra-micro Defect Detection Using Spatial Filtering and Dual Optical Paths
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Solution Overview
Problem
Current detection methods for ultra-micro defects on high-precision smooth surfaces face challenges in achieving a larger imaging field of view while maintaining the ability to detect defects as small as 0.5 microns, resulting in longer detection times and lower efficiency.
Innovation Solution
The proposed solution involves an ultra-micro defect detection apparatus and method that utilizes an optical filtering imaging technology. This includes an imaging module with a camera, imaging lens, and objective lens, a light source module with a collimator and beam splitting mirror, and a filtering module with a spatial filter, specifically an optical high-pass filter, to enhance high-frequency light information and suppress zero-frequency light information, thereby highlighting defects on the surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If 20-fold microscopic imaging technology is used to detect 0.5 micron defects, then detection precision is improved, but imaging field of view decreases to about 0.35 mm×0.25 mm
Solution Approach 1:
The patent divides the imaging system into multiple optical paths with different magnifications. The first optical path uses high magnification (20-fold) for detailed defect inspection, while the second optical path uses low magnification for wide-area coverage. This segmentation allows the system to simultaneously achieve both high precision and large field of view by switching between or combining different optical segments.
Solution Approach 2:
The patent creates a multi-functional imaging system that can perform both high-magnification defect detection and low-magnification wide-area scanning using a single integrated apparatus. The system universally handles different detection requirements by incorporating multiple optical paths with varying magnification capabilities, making it adaptable to both precision and efficiency needs.
2Measurement precision
If high magnification is used to detect smaller defects, then measurement precision is improved, but detection time increases due to smaller imaging field of view
Solution Approach 1:
The patent segments the detection process into two parallel optical paths: one for high-magnification precision detection and another for low-magnification rapid scanning. This allows the system to quickly identify regions of interest using the wide-field path, then focus detailed inspection only on those specific areas using the high-magnification path, thereby reducing overall detection time while maintaining precision.
Solution Approach 2:
The patent implements preliminary scanning using the low-magnification optical path to quickly identify potential defect locations before applying high-magnification inspection. This preliminary action filters out areas without defects, allowing the high-magnification path to focus only on suspicious regions, thus avoiding time-consuming full-area high-res scanning.
3Measurement precision
If optical filtering imaging technology is used to enhance high-frequency light information, then defect visibility is improved, but device complexity increases
Solution Approach 1:
The patent introduces a spatial filter as an intermediary component in the optical path. This filter acts as a mediator that selectively transmits high-frequency light information corresponding to defect features while blocking low-frequency background information. The spatial filter simplifies the complexity by providing a straightforward optical filtering mechanism rather than requiring complex digital processing or multiple sophisticated optical components.
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 enables the detection of ultra-micro defects of 0.5 microns within a large detection range of 14 mm×10 mm, achieving high-speed and high-efficiency defect detection with improved contrast and visibility of defects, suitable for high-precision smooth surfaces.
Implementation Method 1
a filtering module with a spatial filter, specifically an optical high-pass filter, to enhance high-frequency light information and suppress zero-frequency light information
Implementation Method 2
performing optical Fourier transformation on the reflected light rays
Implementation Method 3
a light source module with a collimator and beam splitting mirror
Implementation Method 4
a light source module with a collimator and beam splitting mirror
Data Source
AI summary
The present application discloses an ultra-micro defect detection apparatus and a detection method thereof. The apparatus includes an imaging module, a light source module, a filtering module, and a mounting platform; the imaging module further includes a camera, an imaging lens, and an objective lens; the camera, the imaging lens, and the objective lens are sequentially and vertically arranged from top to bottom; the light source module further includes a collimator, a light source generator, and a beam splitting mirror; the light source generator is connected to the beam splitting mirror, and the collimator is mounted between the light source generator and the beam splitting mirror; the filtering module further includes a spatial filter, and the spatial filter is mounted between the imaging lens and the objective lens.