Optical Inspection Apparatus for Curved Surface Analysis
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Solution Overview
Problem
Conventional optical inspection methods struggle to effectively acquire surface information, particularly for objects with curved surfaces, as they require precise alignment of illumination light with the normal direction of the surface to capture accurate images, limiting their ability to inspect surfaces with varying normal directions simultaneously.
Innovation Solution
An optical inspection apparatus comprising an illumination portion that irradiates object points with differently directed light, a wavelength selection portion with multiple regions that selectively transmit different wavelength spectra, and an imaging portion that captures images through the wavelength selection portion when the normal direction and illumination direction have an opposing relationship, allowing for simultaneous imaging of object points with different normal directions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional optical inspection methods use single-direction illumination, then the alignment is simple, but the ability to capture surfaces with varying normal directions is limited
Solution Approach 1:
The illumination system is segmented into multiple independent light sources, each emitting light in a different direction. This allows the system to illuminate different portions of curved surfaces effectively, with each light source targeting specific surface regions based on their orientation
Solution Approach 2:
The system transitions from single-direction (1D) illumination to multi-directional (3D) illumination by arranging light sources in different spatial positions and orientations, enabling comprehensive coverage of surfaces with varying normal directions
2Measurement precision
If spectral division is used to acquire surface information, then wavelength-specific data is obtained, but the inspection process becomes complex and time-consuming
Solution Approach 1:
Instead of using full spectral division with multiple wavelength bands, the system uses a single broad-spectrum light source that provides sufficient information for surface inspection, achieving adequate measurement precision without the complexity of spectral separation
Solution Approach 2:
The system extracts only the necessary information from the reflected light - specifically the color count and intensity variations - without performing complete spectral analysis, thereby simplifying the inspection process while maintaining surface characterization capability
3Area of stationary object
If multiple illumination directions are used, then coverage of curved surfaces is improved, but the imaging system complexity increases
Solution Approach 1:
A single imaging device is designed to perform multiple functions: capturing images from different illumination directions simultaneously, analyzing color counts across multiple regions, and characterizing surface properties without requiring multiple specialized imaging systems
Solution Approach 2:
The system merges multiple illumination paths and their corresponding image capture functions into a unified inspection system, where a single imaging device receives and processes light reflected from multiple illumination directions through a consolidated optical path
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
Enables contactless identification of surface properties and shape by estimating color counts and BRDF distributions, independent of the normal direction, effectively inspecting curved surfaces without the need for spectral division of illumination.
Implementation Method 1
a wavelength selection portion (26) including at least two wavelength selection regions (52, 54) that selectively transmit light having different wavelength spectra
Implementation Method 2
image light from the first object point through the wavelength selection portion when a normal direction at the first object point and a direction of the first illumination light have an opposing relationship
Data Source
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AI summary
According to one example, an optical inspection apparatus includes: an illumination portion, a wavelength selection portion and an imaging portion. The illumination portion irradiates a first object point of a surface of an object with first illumination light, and a second object point of the surface of the object with second illumination light. The imaging portion images light from the first object point through the wavelength selection portion when a normal direction at the first object point and a direction of the first illumination light have an opposing relationship, and images light from the second object point through the wavelength selection portion when a normal direction at the second object point and a direction of the second illumination light have an opposing relationship.