Optical Inspection System for Mirror Surface Measurement
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Solution Overview
Problem
Conventional optical inspection systems struggle with measuring three-dimensional shapes of objects with mirror surfaces due to low light reflection, leading to poor image contrast and image distortion, which cannot be fully overcome by existing methods.
Innovation Solution
The optical inspection system employs two optical modules with symmetric light sources and image capturing units relative to the normal line of the inspection plane, allowing for better light reflection and image capture, and uses filters to optimize light transmission and reflection, enabling the synthesis of images without shadows and improving measurement range and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a conventional optical inspection system uses a light source and camera positioned above the DUT, then the system structure is simple, but the reflected light intensity is too low for mirror surfaces, resulting in poor image contrast
Solution Approach 1:
The optical inspection system is divided into multiple independent optical modules, each with its own light source and image capturing unit positioned at different angles. This segmentation allows each module to capture reflected light from different directions, collectively solving the low reflected light intensity problem for mirror surfaces while maintaining modular system architecture.
Solution Approach 2:
The system transitions from a single overhead optical path to multiple optical paths positioned at different spatial angles relative to the DUT surface. By adding the dimensional parameter of angular position, the system captures reflected light that would otherwise be directed away from the camera, significantly improving reflected light intensity and image contrast.
2Illumination intensity
If the optical inspection system is modified to follow the law of reflection for better image contrast, then image contrast improves, but shadows and image distortion occur
Solution Approach 1:
By segmenting the optical system into multiple modules positioned at different angles, the system captures images from multiple perspectives. This allows algorithmic synthesis of these images to eliminate shadows and distortions that affect individual views, while each module still benefits from optimized reflection geometry for high contrast.
Solution Approach 2:
The system uses composite optical paths with different angular configurations, combining the advantages of each angle. By synthesizing data from multiple optical paths with different reflection geometries, the system achieves high image contrast while compensating for shadows and distortions through multi-view integration.
3Adaptability or versatility
If multiple optical modules with different angles are used, then measurement range and inspection capability improve, but device complexity increases
Solution Approach 1:
Each optical module is designed with universal functionality to perform the complete inspection process independently. The modular design allows the same basic module structure to be replicated at different angles, reducing overall system complexity while expanding measurement range and adaptability to different inspection requirements.
4Measurement precision
If filters are added to optimize light transmission and reflection, then image quality improves, but device complexity increases
Solution Approach 1:
Filters are selectively applied at specific locations within the optical path where they provide maximum benefit for light transmission optimization. By placing filters locally rather than universally across all optical paths, the system achieves improved image quality while minimizing the overall filter configuration complexity.
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 configuration allows for effective reflection of light from mirror surfaces, reduces shadows in captured images, enhances the inspection of particles and short circuits, and increases the measurement range, resulting in improved image quality and inspection efficiency.
Implementation Method 1
a large amount of the emitted light cannot be reflected to the camera 72, since this light is reflected from the objects in a manner that follows the law of reflection
Implementation Method 2
The first filter is configured to transmit most of light emitted by the first light source and to reflect most of light emitted by the second light source. The second filter is configured to reflect most of the light emitted by the first light source and to transmit most of light emitted by the second light source
Data Source
AI summary
An optical inspection system includes a first optical module and a second optical module. The first optical module includes a first light source having a first optical axis and a first image capturing unit having a first image capturing axis. The first optical axis and the first image capturing axis are symmetric relative a normal line of an inspection plane. A first angle is formed between the first optical axis and the first image capturing axis. The second optical module includes a second light source having a second optical axis and a second image capturing unit having a second image capturing axis. The second optical axis and the second image capturing axis are symmetric relative to the normal line. A second angle is formed between the second optical axis and the second image capturing axis and is different from the first angle.