Multi-Wavelength Optical Inspection for Uniform Surface Asperity Detection
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Solution Overview
Problem
Existing optical inspection methods struggle to accurately acquire surface information of objects in a non-contact manner, particularly distinguishing between smooth surfaces and surfaces with minute asperities, due to limitations in wavelength utilization and illuminance distribution.
Innovation Solution
An optical apparatus and method that employs a light emission portion to emit light of multiple wavelength spectra, using an image-forming optical element array and wavelength emission surfaces to irradiate the same irradiation field with light of different wavelength spectra, utilizing an image-forming optical element array and wavelength emission surfaces positioned at focal planes of image-forming optical elements to superimpose light beams of different wavelengths for uniform illuminance distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If light of a single wavelength is used for illumination, then the optical system is simple, but the ability to distinguish surface features (smooth vs. asperities) is insufficient
Solution Approach 1:
The illumination is segmented into multiple wavelength components using a diffraction grating, which disperses incident light into different wavelength bands that can be directed to different image-forming optical elements. This segmentation enables simultaneous multi-wavelength illumination while maintaining a relatively simple overall system structure.
Solution Approach 2:
The optical system is designed to handle multiple wavelengths universally through the use of wavelength-dispersive elements and arrays of image-forming optical elements that can process different wavelength ranges. This multi-functionality allows the same optical apparatus to detect various surface features that require different wavelength sensitivities.
2Measurement precision
If multiple wavelength spectra are used to improve surface detection, then the detection accuracy improves, but the illuminance distribution becomes non-uniform
Solution Approach 1:
Different regions of the wavelength emission surface are assigned different wavelength spectra locally, with each region optimized for specific surface feature detection. The image-forming optical element array is correspondingly arranged to direct these localized wavelength regions to appropriate detection paths, achieving both multi-wavelength capability and uniform illuminance distribution.
3Illumination intensity
If wavelength emission surfaces are positioned at focal planes, then uniform illuminance distribution is achieved, but the system complexity increases
Solution Approach 1:
The wavelength emission surface and the image-forming optical element array are merged into an integrated configuration where the emission surface is positioned at the focal plane of the optical elements. This merging achieves uniform illuminance distribution while the regular array pattern maintains manageable system complexity through standardized component arrangement.
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
Enhances the ability to detect the presence or absence of minute asperities on object surfaces by utilizing color information, providing accurate surface information through uniform illuminance distribution and improved wavelength utilization.
Implementation Method 1
a light emission portion configured to emit light
Implementation Method 2
The first wavelength emission surface is positioned at or near a focal plane of the first image-forming optical element. The second wavelength emission surface is positioned at or near a focal plane of the second image-forming optical element.
Implementation Method 3
superimpose light beams of different wavelengths for uniform illuminance distribution
Implementation Method 4
acquiring reflected light and transmitted light using an image sensor
Implementation Method 5
acquiring reflected light and transmitted light using an image sensor
Data Source
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AI summary
According to an arrangement, an optical apparatus includes: a light emission portion configured to emit light; an image-forming optical element array; and first and second wavelength emission surfaces. The image-forming optical element array includes first and second image-forming optical elements. The second wavelength emission surface is arranged at a position different from the first wavelength emission surface. The first and second wavelength emission surface respectively include: a first wavelength emission region configured to emit by the light, light of a first wavelength spectrum toward the image-forming optical element array; and a second wavelength emission region configured to emit by the light, light of a second wavelength spectrum toward the image-forming optical element array. The first wavelength emission surface is positioned at a focal plane of the first image-forming optical element. The second wavelength emission surface is positioned at a focal plane of the second image-forming optical element.