Curved Surface Inspection via In-Axis Lamp Placement
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Solution Overview
Problem
Conventional methods for examining curved reflective surfaces, such as bright and dark field lighting, white-light interferometry, and confocal systems, fail to provide sufficient contrast for simple image evaluation, especially for weak structures, and are complex, expensive, and slow.
Innovation Solution
A camera apparatus with a lamp located in the beam path of the objective, utilizing a pinpoint light source to achieve uniform illumination and high contrast by focusing light onto a curved surface, allowing for easy image evaluation and examination of moving surfaces without interrupting motion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If conventional lighting methods (bright/dark field) are used to illuminate curved surfaces, then the surface can be illuminated, but sufficient contrast for image evaluation is not achieved
Solution Approach 1:
The patent applies local quality by positioning the light source at a specific location relative to the camera optical axis (at distance 0.85×f on the optical axis), creating a localized illumination geometry that produces specular highlights only on intact surface areas. This selective illumination enhances contrast by making defective areas appear dark against bright background, directly resolving the contradiction between illumination and evaluation contrast.
2Measurement precision
If complex examination methods (white-light interferometry, confocal systems) are used, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent replaces expensive, complex examination systems (white-light interferometry, confocal systems) with a simple, inexpensive setup using conventional cameras and standardized lighting components. The solution achieves comparable measurement precision through clever geometric arrangement rather than sophisticated optics, directly addressing the contradiction between precision and complexity.
Solution Approach 2:
The patent substitutes complex optical-mechanical examination systems with a simplified optical geometry based solution. Instead of using interferometric or confocal mechanical systems, it employs a camera with a specifically positioned light source that creates contrast through geometric optics, reducing device complexity while maintaining measurement capability.
3Device complexity
If conventional lighting arrangements are used, then the apparatus structure remains simple, but examination speed is too slow for moving surfaces
Solution Approach 1:
The patent enables continuous examination of moving surfaces by using a lighting geometry that captures surface information in brief moments as the surface moves through the illumination zone. The specular highlight configuration allows for high-speed capture without requiring the surface to be stationary, resolving the contradiction between simple structure and examination speed for moving objects.
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
The solution provides high contrast and efficient image evaluation of curved surfaces, enabling the recognition of surface structures with conventional methods and allowing for continuous examination during production processes.
Implementation Method 1
light emitted by the lamp is reflected from the inside of the curved surface into the camera
Implementation Method 2
the curved surface assures that the light at every point of the curvature is focused into the camera
Data Source
AI summary
An apparatus and a method for examining a curved surface (5), having a camera (2) and an objective (3) and a lamp (4), is described. The camera (2) can be aimed at the inside of the curved surface (5), and the lamp (4) can be located such that light (7) emitted by the lamp (4) is reflected from the inside of the curved surface (5) into the camera (2). To attain high contrast with a simple arrangement, the lamp (4) is located in the beam path of the objective (3) of the camera (2).