Ophthalmic Lens Defect Detection via Multi-Wavelength Imaging
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Solution Overview
Problem
Existing methods for inspecting ophthalmic lenses, such as silicone hydrogel contact lenses, often fail to accurately distinguish between defects like holes and bubbles, leading to unnecessary discarding of good products and incorrect process modifications.
Innovation Solution
The method involves illuminating silicone hydrogel contact lenses with different wavelengths of radiation (visible, ultraviolet, or infrared) to capture two images in quick succession, which are then compared to determine the presence of defects, using specialized cameras and image analysis devices to differentiate between defects and bubbles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If single-wavelength radiation inspection is used, then inspection speed is maintained, but defect differentiation accuracy deteriorates
Solution Approach 1:
The inspection process is segmented into multiple sequential imaging steps, each using different wavelengths of radiation. The system captures a first image at one wavelength and a second image at a different wavelength, then compares the images to differentiate between defects and bubbles. This segmentation allows accurate defect identification without requiring all wavelength information simultaneously, managing system complexity.
Solution Approach 2:
The system employs periodic illumination with alternating wavelengths of radiation, switching between first and second wavelengths in sequence. This periodic action enables the capture of multiple wavelength images over time rather than requiring simultaneous multi-wavelength capture, reducing the complexity of the radiation source system while maintaining defect differentiation capability.
2Measurement precision
If multiple wavelengths are used simultaneously, then defect differentiation improves, but inspection time increases
Solution Approach 1:
The system uses periodic illumination switching between different wavelengths rather than simultaneous multi-wavelength illumination. The radiation source alternates between first and second wavelengths in rapid succession, capturing images at each wavelength sequentially. This periodic approach achieves defect differentiation accuracy comparable to simultaneous multi-wavelength inspection while significantly reducing system complexity and inspection time.
Solution Approach 2:
The system captures multiple images of the same lens at different wavelengths and compares them to identify defects. By creating copies of the inspection process at different wavelengths and then comparing the copies, the system achieves accurate defect differentiation without requiring complex simultaneous multi-wavelength analysis, reducing both time and computational complexity.
3Productivity
If rapid sequential imaging is used, then productivity is maintained, but image quality may deteriorate
Solution Approach 1:
The system maintains continuous inspection throughput by implementing rapid sequential imaging without interruption. The radiation source continuously switches between wavelengths and the imaging system continuously captures images in sequence, ensuring no loss of productivity. The continuous action maintains high inspection throughput while the rapid switching minimizes the time between images, preserving image quality for defect detection.
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 approach effectively differentiates between defects and bubbles, reducing errors in quality control and optimizing manufacturing processes by accurately identifying issues in real-time as lenses move through the production line.
Implementation Method 1
illuminating the ophthalmic lens with radiation comprising one or more members of the group consisting of visible, ultraviolet, or infrared radiation
Data Source
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AI summary
Methods for inspecting ophthalmic lenses with different wavelengths of radiation are disclosed herein.