Optical Window Contamination Sensing With Total Internal Reflection
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Solution Overview
Problem
Optical sensors on aircraft windows are prone to contamination from dirt, aviation de-icing fluid, grease, oil, fuel, water droplets, and ice, which reduces their accuracy and reliability, and current systems lack automated methods to assess window cleanliness.
Innovation Solution
A contamination sensor using total internal reflectance (TIR) with collimated light sources and detectors, combined with prisms or polished edges, to measure the loss of light signal across the window surface, allowing for automated detection of contaminants.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If manual inspections are used to check window cleanliness, then the system is simple, but the productivity is low and cannot provide real-time monitoring
Solution Approach 1:
The patent replaces manual mechanical inspection with an automated optical sensing system. The contamination sensor uses light sources and detectors to automatically measure window cleanliness, eliminating the need for manual visual inspections and enabling continuous real-time monitoring without increasing overall system complexity
Solution Approach 2:
The optical sensor system performs self-diagnosis by using its own emitted light to detect contaminants on its observation window. The sensor monitors its own operational status through the contamination detection mechanism, enabling autonomous functionality without requiring external inspection systems
2Measurement precision
If existing contamination sensors are used, then some area is monitored, but the measurement precision is insufficient for the total window surface
Solution Approach 1:
The patent divides the window surface into multiple detection zones using an array of light sources and detectors positioned at different locations. Each light source-detector pair monitors a specific zone, and the combined data provides comprehensive coverage of the entire window surface with high measurement precision for each segment
Solution Approach 2:
The patent transitions from monitoring a small single area to covering the entire two-dimensional window surface by arranging multiple sensing elements in spatial arrays. The segmentation of the window into multiple detection zones along with the specific geometric arrangement of light sources and detectors enables comprehensive area coverage while maintaining measurement precision through the use of total internal reflectance at multiple measurement points
3Reliability
If the optical sensor window becomes contaminated, then the sensor can still operate, but the reliability of readings decreases
Solution Approach 1:
The contamination sensor provides continuous feedback about the window cleanliness status to the aircraft system. By measuring changes in light reflectance caused by contaminants, the system generates real-time data about window condition, enabling feedback-driven decisions about when cleaning or maintenance is required to maintain reading accuracy
Solution Approach 2:
The system performs preliminary detection of contamination before it significantly degrades sensor performance. By continuously monitoring window cleanliness and detecting early signs of contamination through changes in optical properties, the system can trigger maintenance actions before reliability is compromised, preventing accuracy degradation rather than reacting to it
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 provides real-time, automated detection of contaminants, maintaining sensor accuracy and reliability by assessing the emission-to-detection ratio and triggering alerts when contamination exceeds a threshold, ensuring continuous operation.
Implementation Method 1
A contamination sensor using total internal reflectance (TIR) with collimated light sources and detectors, combined with prisms or polished edges, to measure the loss of light signal across the window surface
Data Source
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AI summary
A contamination sensor for an optical sensor observation window includes a source (18, 118, 218, 318, 418), two prisms, a detector (220, 320, 420), and a controller. The source (18, 118, 218, 318, 418) can emit a collimated light beam at an incident angle that is greater than a critical angle of an interface between a fluid and the window. The window has a refractive index greater than the refractive index of the fluid. The prisms can direct the collimated light beam within the window such that the collimated light beam reflects within a contamination detection zone of the window. The detector (220, 320, 420) can receive the collimated light beam. The controller can communicate with the source (18, 118, 218, 318, 418) and detector (220, 320, 420). The controller can calculate an emission/detection ratio defined by a difference between an amount of light emitted by the source (18, 118, 218, 318, 418) and an amount of light that passes from the source (18, 118, 218, 318, 418) to the detector (220, 320, 420) by a total internal reflectance of the window.