Inspection Lighting Solid Angle Control for Feature Detection
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Solution Overview
Problem
Existing inspection lighting systems struggle to detect minute feature points with complex three-dimensional structures due to composite changes in reflection or scattering, which are difficult to isolate from noise, and often require precise control of irradiation solid angles and optical axes, making it challenging to identify features regardless of their location within the field of view.
Innovation Solution
The system configures uniform irradiation solid angles with adjustable divisions into regions of different wavelengths, polarization planes, or light amounts, allowing for the capture of subtle changes in reflection or scattering without directional dependency, using shielding masks and filtering means to form desired solid angle regions within the irradiation area, enabling continuous capture of changes in contrast information across the imaging area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If uniform irradiation solid angles are used for all points on the inspection object, then the inspection system can simplify the control of optical axes and improve ease of operation, but it becomes difficult to obtain desired gradation information for feature points on surfaces without perfect mirror characteristics
Solution Approach 1:
The patent divides the inspection object into multiple regions (first region and second region) with different optical characteristics, and applies different irradiation solid angle settings to each region. For the first region with mirror-like surfaces, a first irradiation solid angle is used, while for the second region with diffuse surfaces, a second irradiation solid angle is used. This local differentiation allows each region to be inspected with optimized parameters, resolving the contradiction between uniform control simplicity and region-specific measurement precision.
2Measurement precision
If the inspection light is irradiated with controlled solid angles to detect feature points, then the ability to detect defects improves, but the system complexity increases due to the need for precise control of irradiation and observation solid angles
Solution Approach 1:
The patent segments the inspection field into multiple regions based on surface optical characteristics, and assigns different irradiation solid angle parameters to each segment. This segmentation approach allows the system to achieve high defect detection precision for different surface types without requiring a single complex control mechanism, as each region can be handled with simplified region-specific parameters.
Solution Approach 2:
The patent changes the parameters of irradiation solid angles according to different inspection regions and defect types. By adjusting parameters such as the angular width and orientation of irradiation solid angles to match the optical characteristics of each region, the system achieves high detection precision without requiring overly complex control mechanisms, as the parameter adjustments are based on pre-characterized region properties.
3Measurement precision
If anisotropic irradiation solid angles are used to obtain gradation in a specific direction, then feature points with inclines in that direction can be detected, but feature points with inclines in other directions cannot be extracted
Solution Approach 1:
The patent employs asymmetric irradiation solid angle configurations tailored to different inspection regions. For regions requiring detection of inclines in specific directions, the irradiation solid angles are oriented asymmetrically to maximize sensitivity to those directions. For regions requiring omnidirectional detection, the system uses multiple irradiation solid angles with different orientations. This asymmetric configuration strategy allows the system to achieve high precision for specific directions when needed, while maintaining versatility for multiple directions through appropriate selection of asymmetric configurations.
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 the detection of minute feature points with complex three-dimensional structures by adjusting irradiation solid angles and observation solid angles to maximize changes in light amounts, enabling precise identification of feature points regardless of their location, even when changes are slight or difficult to distinguish from noise.
Implementation Method 1
a lens 2 disposed between the surface light source 1 and the inspection object W and forming an irradiation solid angle of light emitted from the surface light source 1 and irradiated onto the inspection object W
Implementation Method 2
a first shielding mask M1 configured to form an irradiation solid angle of inspection light irradiated onto each point on the inspection object W by shielding light
Implementation Method 3
the first filtering means F1 configured to divide the inspection light into solid angle regions having partially different optical attributes for light having different wavelength bands, different polarization planes, or light having different light amounts
Implementation Method 4
an imaging device C configured to image light reflected, transmitted, or scattered by the inspection object W, that is, object light returned from an object
Implementation Method 5
an imaging device C configured to image light reflected, transmitted, or scattered by the inspection object W
Data Source
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AI summary
Provided is an inspection lighting device with which, even when changes in light that occur at respective feature points on an object to be inspected are small, the amounts of those changes in light can be determined across the entire field-of-view range, and the feature points can be detected under exactly the same conditions. The inspection lighting device 100 includes a surface light source 1 and a lens 2 that is disposed between the surface light source 1 and an inspection object W, the lens 2 being disposed nearer to the inspection object W such that at least one of a shielding mask M1 and a filtering means F1 is located centered around a focus position of the lens. An irradiation solid angle of light emitted from the surface light source 1 and irradiated onto the inspection object W by the lens 2 is configured to have solid angle regions that have specific optical attributes and that are radially arranged around an optical axis of the irradiation solid angle. The shapes, sizes, and incline angles of irradiation solid angles of the inspection light as well as solid angle regions having specific optical attributes within the irradiation solid angles can be set to be substantially uniform across the entire field of view in accordance with changes that occur at feature points on the inspection object.