Substrate Edge Inspection Using Right-Angled Prisms
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Solution Overview
Problem
Existing inspection apparatuses for substrate edges require multiple optical devices and struggle to precisely measure chamfered widths due to coaxial illumination, which leads to asymmetrical surface inspections and measurement errors from afterimage influences.
Innovation Solution
An apparatus using a first and second right-angled prism, each inclined towards the upper and lower surfaces of the substrate edge, with a single optical device for imaging, and correction plates to adjust light paths, allowing precise measurement of chamfered widths without coaxial illumination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple optical devices are used to inspect upper surface, lower surface and end surface respectively, then inspection coverage is improved, but device complexity increases
Solution Approach 1:
The patent merges multiple inspection functions into a single optical device by using a beam splitter to divide the light path. The single optical device can simultaneously inspect the upper surface, lower surface, and end surface of the substrate edge, eliminating the need for multiple separate optical devices while maintaining comprehensive inspection coverage
Solution Approach 2:
The patent segments the light path using a beam splitter into multiple independent inspection paths. Each path is directed to a different surface (upper, lower, or end) of the substrate edge, allowing a single optical device to perform multiple inspection functions simultaneously through divided optical channels
2Use of energy by moving object
If coaxial illumination is used for inspection, then lighting efficiency is improved, but measurement precision deteriorates due to afterimage influences
Solution Approach 1:
The patent extracts the harmful afterimage effect from the inspection system by removing coaxial illumination. Instead, it uses oblique illumination at a 45-degree angle, which eliminates the afterimage interference that occurs with coaxial lighting while maintaining adequate lighting efficiency for inspection
Solution Approach 2:
The patent changes the illumination angle parameter from 0 degrees (coaxial) to 45 degrees (oblique). This parameter change eliminates the afterimage effect that degrades measurement precision, while the lighting efficiency is maintained through proper positioning of the light source and optical components
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 precise measurement of chamfered widths by preventing afterimage influences and using a single optical device for all surface inspections, reducing measurement errors and improving inspection efficiency.
Implementation Method 1
a first right-angled prism disposed above an edge portion of a substrate such that an inclined surface thereof is directed toward the upper surface of the edge portion of the substrate; a second right-angled prism disposed below the edge portion of the substrate such that an inclined surface thereof is directed toward the lower surface of the edge portion of the substrate
Data Source
AI summary
An apparatus for inspecting an edge portion of a substrate can inspect a defect or a chamfered width on an edge portion of a substrate. First and second right-angled prisms are disposed above and below the edge portion such that inclined surfaces thereof are directed toward the upper surface and lower surface of the edge portion. A lighting part irradiates the edge portion of the substrate with light. A photographing part is disposed adjacent to the edge portion. The photographing part takes an image of the upper surface of the edge portion from light that has passed through the first right-angled prism, an image of the lower surface of the edge portion from light that has passed through the second right-angled prism, and an image of an end surface of the edge portion.