Multiplexed OCT Surface Inspection with Multiple Scanner Heads
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Solution Overview
Problem
Conventional optical coherence tomography (OCT) systems face inaccuracies in imaging objects due to issues with focusing and coherence length, leading to suboptimal surface inspection and defect detection.
Innovation Solution
A multiplexed OCT system with multiple scanner heads and a multiport selector that alternately directs a sample beam to each scanner head, adjusting the optical path to maintain focus and coherence length across the surface, allowing for efficient scanning and defect detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a single scanner head is used in conventional OCT systems, then the device complexity is low, but the imaging speed and productivity are limited
Solution Approach 1:
The patent divides the scanning function into multiple independent scanner heads (at least two), each capable of performing OCT scanning independently. This segmentation allows parallel processing of different regions of the object, thereby increasing imaging speed and productivity while distributing the complexity across modular units.
Solution Approach 2:
The patent combines multiple scanner heads with a shared optical source and detection system through a multiplexer. This merging approach allows the system to achieve high-speed parallel scanning capability while reusing expensive and complex components (laser source, detector, processing electronics), thus improving productivity without proportionally increasing overall device complexity.
2Area of stationary object
If the sample beam is directed to multiple scanner heads simultaneously, then the imaging coverage area increases, but maintaining focus and coherence length becomes difficult
Solution Approach 1:
The patent employs a multiplexer to alternately direct the sample beam to different scanner heads in a periodic time-multiplexed manner. This periodic switching allows each scanner head to receive the beam sequentially, maintaining proper focus and coherence length for each scan while collectively covering a larger area through coordinated operation of multiple heads.
Solution Approach 2:
The system dynamically adjusts the beam routing between scanner heads based on the scanning progress and object geometry. The multiplexer dynamically switches the optical path to direct the beam to the appropriate scanner head for each A-scan, ensuring that each region is scanned by the optimally positioned scanner head while maintaining focus accuracy.
3Measurement precision
If conventional OCT scanning is used, then the system is simple to operate, but defect detection accuracy and measurement precision are insufficient
Solution Approach 1:
The patent implements feedback mechanisms where the system monitors scan position, object surface geometry, and imaging quality metrics. Based on this feedback, the multiplexer and scanner heads dynamically adjust their operation to maintain optimal focus and coherence length, thereby improving defect detection accuracy while managing system complexity through intelligent control.
Solution Approach 2:
The system performs preliminary actions by pre-planning the scan path and pre-positioning the beam routing before actual scanning begins. The multiplexer is configured in advance to direct beams to appropriate scanner heads based on predicted object geometry and scan requirements, ensuring optimal measurement precision from the start of each scan sequence.
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 system achieves high-resolution, efficient surface inspection and defect detection by ensuring that each scanned region is in focus and within the coherence length, enabling accurate characterization of surface and subsurface features.
Implementation Method 1
optical coherence tomography which uses low-coherence interferometry to detect subsurface features and defects
Implementation Method 2
uses low-coherence interferometry to detect subsurface features and defects
Data Source
AI summary
A system and method for surface inspection of an object using multiplexed optical coherence tomography (OCT) is provided. The method includes moving the object relative to two or more scanner heads along a direction of travel; alternatingly directing a sample beam to each of the two or more scanner heads; and when the sample beam is directed at each respective scanner head, scanning comprising: steering the sample beam from the respective scanner head to an unscanned region on the surface of the object; and performing an A-scan of the object.