Confocal Microscope Surface Inspection Depth Calibration
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Solution Overview
Problem
Existing surface inspection methods for medium-sized or large-sized surfaces are limited by the inability to reliably distinguish between actual defects and pseudo-defects, particularly on heavily structured surfaces, leading to a high number of false alarms and manual rework due to insufficient information content in two-dimensional images.
Innovation Solution
A method that projects a three-dimensionally calibrated pattern onto the surface, allowing for simultaneous acquisition and analysis of two-dimensional intensity and color images with depth information, using an area image sensor to enhance detection performance and reduce false alarms by providing additional depth information for anomaly assessment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If two-dimensional image recording is used for surface inspection, then the inspection process is simple and fast, but the ability to distinguish between actual defects and pseudo-defects is insufficient, leading to high false alarm rates
Solution Approach 1:
The patent transitions from two-dimensional image recording to three-dimensional image recording using a confocal microscope. This adds the depth dimension to the inspection, enabling differentiation between surface defects and pseudo-defects based on their vertical position and focus characteristics, thereby improving detection reliability without requiring multiple separate inspection systems
Solution Approach 2:
The patent integrates multiple inspection capabilities within a single confocal microscope system. The microscope simultaneously captures multiple wavelength images (visible light for surface morphology, infrared for material properties) and focuses at multiple depths, nesting these inspection functions within one device rather than requiring separate systems for each measurement type
2Loss of information
If multiple wavelength imaging is used to obtain comprehensive material information, then the information content increases, but the recording time and inspection speed decrease
Solution Approach 1:
The patent employs confocal microscopy with rapid scanning capabilities that continuously capture multiple wavelength images at different focus depths without interruption. The system maintains continuous scanning across the sample surface, acquiring comprehensive multi-wavelength, multi-depth information in an uninterrupted manner, thereby reducing total inspection time while maintaining full information content
Solution Approach 2:
The patent uses periodic scanning at multiple focus depths and wavelengths in a systematic sequence. The confocal microscope rapidly cycles through different focal planes and wavelength channels, acquiring comprehensive data through periodic sampling that efficiently covers the entire parameter space without requiring sequential inspection of each individual parameter
3Measurement precision
If three-dimensional imaging is used to differentiate defects from pseudo-defects, then the detection accuracy improves, but the device complexity and cost increase
Solution Approach 1:
The patent uses a confocal microscope that serves multiple functions: it acts as both a surface morphology imager and a material property analyzer through multi-wavelength capability. The same instrument performs focus variation microscopy for depth information, infrared imaging for material identification, and surface scanning for defect detection, eliminating the need for separate specialized devices for each measurement type
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 integration of depth information significantly improves the detection reliability, accuracy, and classification of surface defects, minimizing false alarms and enhancing the representation of anomalies through three-dimensional visualization, allowing for more precise separation between actual defects and pseudo-defects.
Implementation Method 1
the surface is illuminated by at least one lighting device and recorded with at least one area image sensor
Implementation Method 2
a pattern is projected onto an area of the surface of the image by means of a projection device calibrated three-dimensionally to the selected coordinate system
Data Source
Figure 1
Figure 2~3
AI summary
The invention relates to a method and a device for inspecting surfaces (3) of an examined object (2), wherein the surface (3) is illuminated by means of at least one illuminating apparatus (8) and recorded by means of at least one area image sensor (6), wherein the recorded images are fed to an image-analyzing apparatus (11), which is designed to detect surface anomalies as flaw areas in a detection process and optionally to delimit the flaw areas in a segmentation process with respect to each other or against the image background, to combine associated flaw areas in a regional analysis process, and/or to derive characteristic flaw features from flaw areas or flaw regions in a feature extraction process, wherein the area image sensor (6) is three-dimensionally calibrated to a selected coordinate system (5) and the examined object (2) having the surface (3) is moved relative to the area image sensor (6). A pattern (10) is projected onto a region of the surface (3) of the object (2) by means of a projection apparatus (8) three-dimensionally calibrated to the selected coordinate system (5), which region is recorded by the area image sensor (6), and the positions of defined pattern sections of the projected pattern (10) on the surface (3) of the object (2) in the selected coordinate system are determined.