Inspection Lighting Device Uniform Solid Angle Control
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Solution Overview
Problem
Conventional inspection lighting devices struggle to detect small or vague defects on products with non-perfect mirror surfaces due to significant contrast variations and irregular light distribution, making it difficult to accurately identify minute feature points.
Innovation Solution
The inspection lighting device employs a configuration where the irradiation solid angles are made uniform and divisible into regions with different optical attributes, such as wavelength bands, polarization planes, or light amounts, allowing for adjustable irradiation patterns to capture subtle changes in reflection or scattering caused by defects, enabling precise detection of minute features.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the irradiation solid angle is made large to cover the inspection area, then the inspection coverage is improved, but the uniformity of light distribution and contrast consistency deteriorates
Solution Approach 1:
The patent divides the inspection system into two independent optical paths: an irradiation optical path that delivers light to the inspection object, and an observation optical path that collects reflected light. This segmentation allows independent optimization of each path - the irradiation path can provide uniform wide-area coverage while the observation path maintains consistent contrast by controlling its specific observation solid angle
Solution Approach 2:
The patent implements different optical characteristics for different parts of the system. The irradiation optical path uses a large solid angle for broad coverage, while the observation optical path uses a controlled solid angle for consistent contrast. This local differentiation of optical properties resolves the contradiction between coverage area and contrast consistency
2Illumination intensity
If the observation solid angle is increased to capture more reflected light, then the brightness of captured images is improved, but the ability to detect small defects deteriorates
Solution Approach 1:
By separating irradiation and observation into independent optical paths with controlled solid angles, the system can optimize brightness and defect detection precision independently, resolving the contradiction between these two parameters
Solution Approach 2:
The patent carefully controls the observation solid angle parameters to optimize defect detection. By maintaining a specific observation solid angle that is not overly large, the system preserves sensitivity to small reflection direction changes caused by defects while still achieving sufficient brightness through proper optical design
3Object-generated harmful factors
If an aperture stop is used to limit the irradiation area and reduce stray light, then the reduction of stray light is improved, but the brightness uniformity across the inspection area deteriorates
Solution Approach 1:
The patent separates the functions of stray light control and uniform illumination into different components. The beam splitter efficiently separates irradiation and observation paths, while the observation objective's controlled solid angle inherently limits stray light reception. This segmentation achieves both stray light reduction and brightness uniformity without requiring additional aperture stops that would create non-uniform illumination
Solution Approach 2:
The beam splitter acts as an intermediary that efficiently directs light between the irradiation source and observation system. This intermediary component enables clean separation of optical paths, allowing independent optimization of stray light rejection and illumination uniformity
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 solution allows for the detection of minute defects by ensuring uniform irradiation and adjustable optical attributes within the irradiation solid angles, providing consistent contrast information across the imaging area and enhancing the ability to identify small changes in light amounts, even on complex surfaces.
Implementation Method 1
a lens disposed between the surface light source and the inspection object and configured to form on the inspection object an irradiation solid angle of light emitted from the surface light source
Implementation Method 2
a first filtering means disposed between the surface light source and the lens and in front of or behind a focal distance position of the lens... configured to divide the inspection light into solid angle regions as desired, the 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 3
the 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 for imaging light reflected, transmitted, or scattered by the inspection object
Implementation Method 5
an imaging device for imaging light reflected, transmitted, or scattered by the inspection object
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. An 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 focal distance 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 as desired, the solid angle regions having specific optical attributes. The shapes, sizes, and inclination 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.