Optical Inspection Surface State Discrimination Using Wavelength Spectrum Selection
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Solution Overview
Problem
Current optical inspection methods struggle to accurately differentiate between surface states, such as matte and glossy surfaces, due to reliance on color information that is influenced by the surface's inherent color rather than its structural properties.
Innovation Solution
The implementation of a color filter with distinct wavelength spectrum selection regions allows specific wavelength spectra to pass through, enabling the acquisition of color vectors that reflect surface state characteristics independent of the surface's color, thereby discriminating surface states based on the direction of these vectors in a color coordinate system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If color information from a normal camera is used for surface inspection, then the inspection process is simple, but the accuracy of surface state differentiation is insufficient due to color interference
Solution Approach 1:
The patent segments the color information into two independent components: color vectors (representing surface state) and brightness values (representing illumination). This is achieved by acquiring images through multiple wavelength spectrum selection regions and calculating color vectors from the pixel values. The segmentation allows surface state inspection to be performed on color vectors independently, eliminating the interference of surface color while maintaining a relatively simple inspection system structure.
2Measurement precision
If multiple wavelength spectra are selected to improve surface state inspection accuracy, then measurement precision improves, but device complexity increases
Solution Approach 1:
The patent implements a color filter with multiple wavelength spectrum selection regions (first, second, and third regions) that can be selectively activated. Each wavelength spectrum selection region serves multiple functions: it acts as a bandpass filter for specific wavelength ranges, enables color vector calculation for surface state inspection, and can be combined with brightness value acquisition for comprehensive surface analysis. This multi-functionality allows the system to achieve high measurement precision while maintaining device compactness and avoiding excessive complexity.
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 allows for effective inspection of surface states by isolating directional information from color information, enabling accurate differentiation between surface states like matte and glossy surfaces, regardless of their inherent colors.
Implementation Method 1
acquiring a color vector of a color corresponding to a wavelength spectrum... with optical imaging using a wavelength spectrum selection portion that selectively allows a plurality of wavelength spectra different from one another from a surface of the subject to pass
Data Source
AI summary
According to the embodiment, an optical inspection method for a surface state of a subject includes acquiring and discriminating. The acquiring includes acquiring a color vector of a color corresponding to a wavelength spectrum in a color coordinate system of n dimensions (n is a natural number equal to or larger than 1), which is equal to or smaller than a number of a plurality of color channels of pixels of an image sensor, with optical imaging using a wavelength spectrum selection portion that selectively allows a plurality of wavelength spectra different from one another from a surface of the subject to pass. The discriminating includes discriminating the surface state of the subject based on a direction of the color vector in the color coordinate system.