Oblique Mirror Light Guide for Optical Inspection Illumination
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Solution Overview
Problem
Optical inspection apparatuses using bright-field optical systems face illuminance unevenness due to specular reflected light components, leading to noise in image recognition and difficulties in accurately identifying surface shapes of inspection targets.
Innovation Solution
An optical inspection apparatus with a polygonal cylindrical light guide and oblique mirror surfaces that reflect light from multiple light sources positioned at corner portions, minimizing the number of light sources and reducing specular reflected light noise by distributing light obliquely across the inspection target.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a bright-field optical system using specular reflected light components is used for image recognition, then the surface shape of the inspection target can be inspected, but illuminance unevenness occurs causing noise in image recognition
Solution Approach 1:
The patent converts the harmful specular reflected light into useful illumination by using a light guide with oblique mirror surfaces. The mirror surfaces reflect light from multiple light sources to create oblique illumination on the inspection target, transforming the problematic specular reflection into a beneficial lighting scheme that reduces illuminance unevenness while maintaining surface shape inspection capability
Solution Approach 2:
The patent changes the illumination parameters by using multiple light sources positioned at different locations and angles, with the light guide distributing this light obliquely across the inspection target. This parameter change from conventional direct illumination to oblique multi-source illumination reduces illuminance unevenness and associated noise in image recognition
2Object-affected harmful factors
If multiple light sources are used to improve illumination uniformity, then illuminance unevenness is reduced, but the number of light sources and device complexity increases
Solution Approach 1:
The patent introduces a light guide with oblique mirror surfaces as an intermediary between the light sources and the inspection target. This intermediary component distributes light from multiple sources in a controlled oblique manner, achieving uniform illumination without requiring complex direct positioning of multiple light sources, thus reducing device complexity while maintaining illumination uniformity
3Device complexity
If the number of light sources is reduced to simplify the device, then manufacturing cost is reduced, but light intensity may become insufficient
Solution Approach 1:
The patent merges multiple light sources into a unified illumination system through the light guide with oblique mirror surfaces. By combining the illumination functions of multiple sources and distributing them through the light guide, the system achieves sufficient overall light intensity while using fewer individual light sources, reducing manufacturing cost without sacrificing illumination adequacy
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 enables accurate inspection of surface shapes with reduced noise and manufacturing costs, while maintaining sufficient light intensity and a compact design, allowing for efficient heat management and precise imaging.
Implementation Method 1
The plurality of mirror surfaces are configured to reflect light entered into the light guide from the light sources through the first end face toward the inspection target
Data Source
AI summary
An optical inspection apparatus includes an imaging optical system facing an inspection target, a light guide, a plurality of light sources, and a plurality of mirror surfaces. The light guide has a plurality of corner portions and extending along an optical axis of the imaging optical system. The plurality of light sources face a first end face of the light guide at positions corresponding to the plurality of corner portions. The plurality of mirror surfaces are respectively provided on second end faces of the light guide. Each of the mirror surfaces is oblique relative to the optical axis. The mirror surfaces are configured to reflect light entered into the light guide from the light sources toward the inspection target.