Diffusive Illumination Structure for Glossy Surface Topography
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Solution Overview
Problem
Traditional optical methods are inadequate for measuring the topography of high-curvature glossy surfaces, as they are expensive, slow, and provide poor accuracy, and manual inspection is subjective and unreliable, failing to detect small defects effectively.
Innovation Solution
An optical arrangement using a diffusive, semi-transparent illumination structure with pinhole-like apertures, multiple light sources, and imaging devices to form and analyze predetermined illumination patterns, enabling accurate measurement of surface properties like orientation and shape, even on high-curvature glossy surfaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional optical methods are used for measuring glossy surfaces, then the measurement process is simple, but the measurement precision and reliability are poor
Solution Approach 1:
The illumination structure is divided into multiple independent light sources arranged in an array, each capable of being controlled separately to create different illumination patterns. This segmentation allows precise control over how light interacts with the glossy surface from multiple angles, improving measurement precision while maintaining manageable system complexity through modular design
Solution Approach 2:
A diffusive semi-transparent illumination structure is introduced as an intermediary between the light sources and the target object. This intermediary scatters and diffuses the light to create controlled illumination patterns that reduce specular reflections from glossy surfaces, enabling accurate optical measurements without requiring complex anti-reflection coatings or multiple external components
2Productivity
If manual inspection is used for quality control, then the equipment cost is low, but the productivity and reliability are insufficient
Solution Approach 1:
The manual inspection process is replaced with an automated optical measurement system using multiple light sources, imaging devices, and computer-controlled analysis. This substitution eliminates human subjectivity and fatigue, significantly improving productivity and reliability of defect detection on glossy surfaces while the modular design keeps the added complexity manageable
Solution Approach 2:
The system changes multiple illumination parameters simultaneously - including illumination angle, intensity distribution, and pattern configuration - to optimize the interaction with glossy surfaces. By dynamically adjusting these parameters through controlled illumination patterns, the system achieves high-speed automated inspection with improved reliability over manual methods
3Measurement precision
If point-by-point scanning methods are used, then the device complexity is low, but the measurement precision and time consumption are problematic
Solution Approach 1:
The system transitions from one-dimensional point-by-point scanning to simultaneous multi-point measurement by using multiple light sources and imaging devices that capture surface information across the entire field of view at once. This dimensional expansion from sequential to parallel measurement dramatically reduces time consumption while maintaining high precision through the coordinated illumination patterns
Solution Approach 2:
Multiple light sources are pre-positioned and configured to illuminate the target surface from different angles simultaneously before the measurement process begins. The illumination patterns are pre-planned and coordinated, allowing the imaging devices to capture complete surface information in a single exposure or minimal exposures, eliminating the time-consuming sequential scanning process
4Adaptability or versatility
If flat digital display and camera method is used, then the device complexity is moderate, but the adaptability to high-curvature surfaces is limited
Solution Approach 1:
The illumination structure is designed with curved or three-dimensional geometry that can conform to and adapt to the curvature of the target surface. By arranging light sources in a curved array and using a diffusive semi-transparent structure, the system can maintain effective illumination angles and pattern projection on high-curvature surfaces, significantly improving adaptability while the modular design keeps complexity manageable
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 precise and reliable measurement of 3D shape, orientation, and dimensions of glossy surfaces, detecting small defects with good accuracy and reliability, using affordable hardware and rapid image analysis.
Implementation Method 1
a diffusive, semi-transparent illumination structure defining a hollow surface shape configured to surround the target object at least partially
Implementation Method 2
the surface being further provided with at least two pinhole-like apertures, a number of light sources optically coupled to the diffusive illumination structure for illuminating the target object via the surface of the illumination structure
Implementation Method 3
at least two imaging devices, each configured to image the target object via an aperture of said at least two apertures
Data Source
Figure 1~2
Figure 3~4a
Figure 4b~6
AI summary
An arrangement (101, 201) for optically measuring the surface, such as surface shape and/or related surface defects, of an optionally glossy target object (106, 206), comprising: a diffusive, semi-transparent illumination structure (102, 202, 302) defining a hollow, preferably curved, surface shape configured to surround the target object at least partially, preferably substantially at least hemispherically, the surface being further provided with at least two, preferably substantially pinhole-like and optionally lens-provided, apertures (212),a number of light sources (208) optically coupled to the diffusive illumination structure for illuminating the target object via the surface of the illumination structure,at least two imaging devices (104, 204), each configured to image the target object via an aperture of said at least two apertures,and a control entity (210) configured to instruct said number of light sources to form a sequence of predetermined illumination patterns illuminating the target object(i.e. a video sequence of images projected on the target object)via the surface of the illumination structure, to instruct the at least two imaging devices to obtain an image of the target object relative to each illumination pattern, and to derive, through the utilization of said pat- terns utilized and images obtained, a predetermined surface-related property of the target object.A corresponding measurement method is presented.