Single-Pixel Optical Inspection Wavelength Selection for Defect Detection
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Solution Overview
Problem
Current optical inspection methods using single-pixel imaging struggle to effectively acquire information on the directional distribution of light from multiple object points, particularly in detecting minute defects or variations in light scattering characteristics, due to limitations in wavelength selection and sensitivity.
Innovation Solution
An optical inspection apparatus comprising a single-pixel light receiving element, an image formation optical element, and a light beam selection portion that selectively shields specific wavelengths, allowing for the acquisition of directional distribution information by distinguishing between different wavelength spectra and identifying minute defects or variations in light scattering.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single light receiving element is used for single pixel imaging, then high sensitivity for detecting weak light is achieved, but the ability to acquire directional distribution information of light from multiple object points is insufficient
Solution Approach 1:
The patent divides the light receiving process into multiple wavelength bands by placing wavelength selection filters (first, second, and third wavelength selection filters) in the optical path. Each filter segment captures light from different wavelength ranges, allowing the single light receiving element to acquire directional distribution information for multiple wavelengths separately, thereby resolving the contradiction between high sensitivity and information completeness.
2Productivity
If pattern lights are correlated with time-series signals from a single light receiving element, then imaging of transmittance or reflectance distribution is achieved, but detection of minute defects or variations in light scattering characteristics is difficult
Solution Approach 1:
The patent changes the wavelength parameter of light by using multiple wavelength selection filters with different spectral characteristics. By acquiring images at multiple wavelengths and comparing them, the system can detect minute defects or variations in light scattering characteristics that would be invisible at a single wavelength, thereby improving measurement precision while maintaining imaging productivity.
3Loss of information
If all wavelengths from object points are received by the single-pixel light receiving element, then complete light information is acquired, but selective shielding of specific wavelengths is not possible, reducing inspection accuracy
Solution Approach 1:
The patent introduces dynamic wavelength selection by placing wavelength selection filters that can be switched or combined in different configurations. This allows the system to dynamically select which wavelengths to receive or shield based on the inspection requirements, achieving both complete light information acquisition and selective wavelength shielding for improved inspection accuracy.
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
Enables accurate detection of minute defects and variations in light scattering characteristics across multiple object points by selectively filtering wavelengths, enhancing the sensitivity and resolution of directional distribution analysis.
Implementation Method 1
a light beam selection portion (26) provided between the image formation optical element (24) and the single-pixel light receiving element (22) and having a first wavelength selection region (51) that allows light of a first wavelength spectrum to pass therethrough and shields light of at least one remaining wavelength spectrum different from the first wavelength spectrum
Implementation Method 2
a single-pixel light receiving element (22) configured to receive image points (I1 to I4) corresponding to at least two different object points (O1 to O4) of the object (O) and to output a light intensity signal
Data Source
AI summary
According to the embodiment, an optical inspection apparatus includes a single-pixel light receiving element, an image formation optical element, and a light beam selection portion. The image formation optical element is disposed at a position where the single-pixel light receiving element configured to receive image points corresponding to at least two different object points of an object. The light beam selection portion is provided between the image formation optical element and the single-pixel light receiving element and is configured to selectively shield at least one wavelength included in lights from the object points.