Surface Optical Inspector for Transparent Solid Defect Detection
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Solution Overview
Problem
Detecting defects in transparent solids with abutting surfaces is challenging due to the difficulty in separating scattered light from the top and bottom surfaces, which complicates the inspection process, especially when a first transparent solid is placed on a second transparent solid.
Innovation Solution
A surface optical inspector directs a source beam onto a transparent solid and measures various types of radiation, including specular reflection, near specular scattered radiation, and large angle scattered radiation, to determine the type and location of defects on the surface, utilizing these measurements to differentiate between defects such as particles, bubbles, pits, and stains on either surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple radiation measurements are taken to improve defect detection accuracy, then measurement precision improves, but device complexity increases
Solution Approach 1:
The patent segments the scattered radiation measurements into two distinct angular categories: near-specular scattered radiation (NSSR) and large-angle scattered radiation (LASR). This segmentation allows the system to differentiate between defects on the first surface versus the second surface of the transparent solid, thereby improving measurement precision without requiring a single overly complex measurement system. Each radiation type is detected by dedicated sensors positioned at specific angular ranges.
Solution Approach 2:
The patent introduces angular dimension as an additional measurement parameter by measuring scattered radiation at different angles (near-specular vs. large-angle). This dimensional approach enables the system to distinguish between defects on different surfaces of the transparent solid, improving defect detection accuracy while maintaining manageable device complexity through geometric differentiation rather than complex signal processing.
2Difficulty of detecting and measuring
If scattered radiation measurements are taken to detect defects on both surfaces, then defect detection capability improves, but difficulty in separating light from different surfaces increases
Solution Approach 1:
The patent segments the scattered radiation detection into two distinct angular channels: near-specular scattered radiation (NSSR) and large-angle scattered radiation (LASR). This segmentation preserves information about which surface the scattered light originated from, as defects on the first surface primarily scatter light at near-specular angles while defects on the second surface scatter at large angles. This resolves the information loss problem while maintaining comprehensive defect detection capability.
Solution Approach 2:
The patent uses the angular distribution of scattered radiation as an intermediary parameter to indirectly determine defect location. Instead of directly measuring which surface a defect is on, the system measures the angular characteristics of scattered light, which serves as a mediator that encodes surface location information. This intermediary approach enables surface-specific defect detection without direct physical separation of the light paths.
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 method effectively identifies and classifies defects on transparent solids, preventing defects like air gaps and particles from causing operational issues in display devices by accurately determining the type and location of defects, thereby improving the quality control in manufacturing.
Implementation Method 1
The types of radiation include specular reflection, specular reflection angle, near specular scattered radiation, and large angle scattered radiation
Implementation Method 2
The types of radiation include specular reflection, specular reflection angle, near specular scattered radiation, and large angle scattered radiation
Data Source
AI summary
A method and apparatus to measure specular reflection intensity, specular reflection angle, near specular scattered radiation, and large angle scattered radiation and determine the location and type of defect present in a first and a second transparent solid that have abutting surfaces. The types of defects include a top surface particle, an interface particle, a bottom surface particle, an interface bubble, a top surface pit, and a stain. The four measurements are conducted at multiple locations along the surface of the transparent solid and the measured information is stored in a memory device. The difference between an event peak and a local average of measurements for each type of measurement is used to detect changes in the measurements. Information stored in the memory device is processed to generate a work piece defect mapping indicating the type of defect and the defect location of each defect found.