MWIR Flame Detection Using Uncooled Bolometer Arrays
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Solution Overview
Problem
Current flame detection technologies face challenges in distinguishing flames from hot objects and backgrounds, particularly in mid-wave infrared (MWIR) radiation, due to similar intensity ratios and the need for high temperature resolution, which can lead to false positives and inefficient discrimination.
Innovation Solution
A modified bolometer pixel array system using a sapphire window or AlON filter to selectively detect MWIR radiation, combined with image processing techniques for spatial and temporal analysis, to differentiate flames from hot objects by analyzing flicker patterns and intensity variations, reducing false positives and improving detection accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If MWIR detection is used to sense flames, then the intensity ratio between flame and background is much larger making discrimination easier, but cooled solid state InSb detectors are required which reduces ease of manufacture and increases device complexity
Solution Approach 1:
The patent changes the operating wavelength parameter from MWIR to LWIR, allowing the use of uncooled bolometer detectors instead of cooled InSb detectors. This parameter change resolves the contradiction by maintaining flame detection capability while eliminating the need for complex cooling systems.
Solution Approach 2:
The patent employs inexpensive uncooled bolometer detector arrays instead of expensive cooled InSb detectors. These simpler detectors can be mass-produced at lower cost and do not require maintenance of cooling systems, resolving the contradiction between detection precision and device complexity.
2Measurement precision
If cooled InSb detectors are used for MWIR detection, then good temperature resolution is achieved, but the system becomes less adaptable to different applications and more difficult to operate
Solution Approach 1:
The patent uses uncooled bolometer detectors that can detect both flame radiation and background thermal radiation in the LWIR spectrum. This universal detection capability allows the same system to be applied to various fire detection scenarios without requiring specialized cooled detectors, resolving the contradiction between precision and adaptability.
3Ease of operation
If LWIR detection is used, then uncooled bolometer detectors can be employed simplifying the system, but the intensity ratio between flame and background is smaller making discrimination more difficult
Solution Approach 1:
The patent transitions from single-pixel MWIR detectors to multi-pixel LWIR bolometer arrays, adding spatial dimensionality to the detection. This allows the system to capture spatial-temporal texture patterns of flames across multiple pixels, compensating for the smaller intensity ratio in LWIR and resolving the contradiction between simplicity and precision.
Solution Approach 2:
The patent employs dynamic temporal analysis of flame characteristics by capturing video sequences and analyzing spatial-temporal texture patterns. This dynamic approach exploits the temporal variability of flame structures to achieve reliable discrimination despite the smaller intensity ratio in LWIR, resolving the contradiction between system simplicity and detection precision.
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 effectively discriminates flames from hot objects and backgrounds by leveraging MWIR detection and image processing, enhancing the accuracy and reliability of flame detection while reducing false positives, allowing for early hazardous fire detection in diverse environments.
Implementation Method 1
A use of an Al 2 O 3 window rather than a Si window on a vacuum package may ensure that only MWIR radiation reaches the array. The Al 2 O 3 window may act as a filter that passes IR radiation having a wavelength below 6 microns
Implementation Method 2
The present disclosure may describe a method and system for detecting flames in the MWIR with bolometer technology
Implementation Method 3
One approach may be to sense mid-wave infrared (MWIR) radiation from a flame
Data Source
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Figure 2b
AI summary
A system for detecting a flame. The system may discriminate between a detected hot object and flame. The system may be a camera-like structure incorporating an infrared sensor, a lens, and an element that could filter out some of the long-wave infrared radiation. The sensor may receive radiation of a scene which forms images on the sensor. The images may be provided to a processor that incorporates one or more modules to determine whether a flame is present in the scene.