Fix Focus IR System Optical Path Maintenance Decision Method
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Solution Overview
Problem
Existing electro-optical systems face challenges in maintaining optical path reliability due to defocusing caused by focus shift and changes in detector characteristics, which are not effectively addressed by traditional methods, leading to image degradation and the need for frequent NUC/BPR updates.
Innovation Solution
A method that examines pixel-wise offset value differences and bad pixel clusters to determine maintenance needs, using histograms to detect defocusing and excessive bad pixel increases, allowing for timely updates of NUC/BPR tables without requiring external setups or specific targets.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional MTF measurement methods are used to detect focus shift, then focus status can be measured, but it requires specific target setups (sine, sinusoidal Siemens star, point, line or edge target) that are not feasible at operational field for fix focus systems
Solution Approach 1:
The system uses its own detector characteristics and operational images to self-diagnose focus status without requiring external target setups. The method leverages the detector's response to scene content already captured during normal operation, eliminating the need for specialized MTF targets while maintaining focus detection capability.
Solution Approach 2:
The patent introduces an intermediary approach by using detector offset variations as a proxy indicator for focus status. Instead of directly measuring MTF through complex target setups, the system uses the change in detector characteristics (offset values) as a mediator to infer focus condition, making the measurement feasible during normal operational field use.
2Reliability
If 1 point NUC/BPR is performed at each power up to compensate detector aging, then detector characteristics changes can be addressed, but excessive increase in total number of bad pixels detected indicates suspicious replacement of all bad pixels
Solution Approach 1:
The system performs preliminary analysis of detector characteristics changes by monitoring offset variations and bad pixel patterns before initiating full NUC/BPR procedures. This early detection allows the system to determine whether minor adjustments or comprehensive recalibration are needed, preventing unnecessary replacement of all bad pixels while ensuring accurate compensation.
Solution Approach 2:
The patent implements feedback mechanisms by continuously monitoring detector performance metrics (offset values, bad pixel counts, cluster patterns) and using this information to adjust NUC/BPR operations. The system feeds back detector status information to determine the appropriate level of correction needed, improving both reliability and measurement precision in the process.
3Reliability
If focus shift occurs due to environmental conditions, then defocusing is caused, but traditional MTF measurement cannot be performed without specific target setups in operational field
Solution Approach 1:
The system self-diagnoses focus stability by monitoring its own detector offset characteristics during normal operation. This self-service approach eliminates the need for external MTF measurement targets and complex setup equipment, allowing focus status assessment using only the detector's inherent properties and operational image data.
Solution Approach 2:
The patent changes the measurement parameter from direct MTF calculation (requiring specific targets) to detector offset value analysis. By monitoring changes in detector characteristics parameters (offset, bad pixel distribution) rather than direct optical performance metrics, the system can assess focus stability without complex target setups.
4Reliability
If detector aging causes change in detector characteristics, then RFPN increases over time, but 2 point NUC/BPR tables need to be updated which requires additional operational steps
Solution Approach 1:
The system performs preliminary monitoring of detector characteristics changes through continuous analysis of offset values and bad pixel patterns. This early detection allows the system to proactively determine when NUC/BPR table updates are needed, optimizing the timing of maintenance operations to balance image quality consistency with operational efficiency.
Solution Approach 2:
The patent implements feedback-based decision making by continuously monitoring detector performance metrics and using this information to determine when NUC/BPR updates are necessary. The feedback loop analyzes changes in detector characteristics and automatically triggers appropriate maintenance actions, improving both reliability through timely updates and productivity by avoiding unnecessary operational steps.
Data Source
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AI summary
The invention presents a method that determines optical path maintenance need before any critical failure in operation of the system. In order to indicate the maintenance need due to the defocusing, the pixel-wise offset value differences between 2 point NUC and 1 point NUC are examined. When the width of this pixel-wise offset difference histogram is greater than predefined threshold, maintenance need is raised. The change in detector characteristics and the need for 2 point NUC/BPR update are proposed to be determined after 1 point NUC by controlling the total number of the bad pixels and bad pixel clusters.