Dual-optical sensor alignment using knife edges
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Solution Overview
Problem
Dual-optical displacement sensor systems face challenges in accurately aligning the optical axes of scanner heads to minimize thickness measurement errors in lithium-ion battery electrode manufacturing, where existing alignment tools are not sufficiently accurate, leading to potential misalignment due to temperature changes and varying angles relative to the coated sheet material.
Innovation Solution
A method utilizing a dual-optical sensor system with an alignment target featuring four knife edges, oriented perpendicular to the optical axes, to enable high-accuracy alignment and continuous monitoring for realignment, allowing for precise adjustment of the optical axes alignment using a computer-controlled process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional alignment tools are used to align the optical axes of scanner heads, then the alignment process can be completed, but the alignment accuracy is insufficient (no better than 50 μm)
Solution Approach 1:
A laser alignment target is introduced as an intermediary object between the two scanner heads. The target contains a laser alignment feature (such as a reflective surface or transmissive marker) that enables precise optical axis alignment. By scanning both heads over the same physical target feature, the system achieves sub-50 μm alignment accuracy without requiring complex alignment tools. The target acts as a common reference that mediates the alignment process between the two independent scanner heads.
2Measurement precision
If the optical axes are aligned initially, then thickness measurement accuracy is improved, but temperature changes cause misalignment over time
Solution Approach 1:
The system performs preliminary alignment using the laser alignment target before thickness measurements begin. The alignment is stored as reference data. When temperature changes cause misalignment, the system can detect the deviation by re-scanning the alignment target and compare it to the stored reference, then apply corrective transformations to maintain measurement accuracy throughout the operational period.
Solution Approach 2:
The system continuously monitors alignment by re-scanning the laser alignment target at intervals during operation. When misalignment is detected (indicating temperature-induced drift), the system generates feedback to realign the scanner heads by applying geometric transformations based on the measured deviation from the reference alignment, thereby maintaining thickness measurement accuracy despite environmental changes.
3Measurement precision
If multiple alignment adjustments are performed to achieve co-linearity, then measurement errors are reduced, but the alignment process becomes more time-consuming
Solution Approach 1:
The system replaces manual, iterative mechanical alignment adjustments with an automated computational approach. The laser alignment target provides objective reference data that is processed by software to calculate precise geometric transformations. This substitution of mechanical trial-and-error adjustment with optical measurement and computational geometry enables alignment to be achieved in fewer steps with higher precision, reducing the overall alignment time despite the increased sophistication of the method.
Data Source
AI summary
A dual-optical displacement sensor system includes a scanner including a first and second scanner head including optical displacement sensors providing a first and second beam having a first optical axis (OA) and a second OA. A computing device or programmed circuit is coupled to receive time versus position data from measurements involving alignment target(s) including at least one knife edge pair including a first and second knife edge oriented in a first plane of the alignment target that is essentially perpendicular to the OAs positioned between the scanner heads for interacting with the beams, and implement at least one equation to analyze the data for determining a degree of alignment of the first and second OA. Using the degree of alignment, an algorithm is for automatic alignment of the OAs or assist instructions for a user alignment of the OAs that provides guiding steps for the user for the alignment.