Gas Quantification in Passive Optical Gas Imaging
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Solution Overview
Problem
Conventional thermal imaging systems face challenges in detecting and quantifying gas leaks due to low sensitivity, especially in uncooled devices, where noise and interference from physical aspects like temperature variations and aerosol particles obscure gas detection, making it difficult to differentiate between gas information and noise in infrared images.
Innovation Solution
The method involves generating a quantified scene difference infrared image by controlling an infrared imaging system to capture images in specific wavelength bands, determining high and low absorption bands based on estimated noise and absorption spectra, and using a gas-quantifying relation to express pixel values in parts per million * meter, thereby improving contrast and sensitivity in gas-absorption-path-length images.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional thermal imaging devices are used for gas detection, then the system can capture infrared radiation from the scene, but the sensitivity is too low to detect gas below a certain concentration due to noise and interference from temperature variations and aerosol particles
Solution Approach 1:
The patent segments the infrared spectrum into multiple wavelength bands, with at least one band specifically selected to match the absorption characteristics of the target gas. By dividing the broadband infrared detection into narrowband spectral channels, the system can isolate gas-specific absorption signals from background noise and interference from other sources such as temperature variations and aerosol particles.
Solution Approach 2:
The patent applies local quality by enhancing detection sensitivity at specific wavelength bands where the target gas exhibits characteristic absorption. Instead of uniform detection across all infrared wavelengths, the system concentrates measurement resources on spectral regions with high gas absorption coefficients, thereby improving local measurement precision where it matters most for gas detection.
2Measurement precision
If narrow wavelength bands are used for gas imaging based on absorption difference, then gas detection contrast improves, but noise contribution from imaging device components such as filters, optical systems, wave guide and detector increases significantly
Solution Approach 1:
The patent employs dynamic wavelength tuning capability, allowing the imaging system to adaptively select and switch between different wavelength bands based on the specific gas being detected and environmental conditions. This dynamic adjustment optimizes the balance between gas absorption contrast and noise levels, enabling the system to operate at the optimal spectral region for each detection scenario rather than being fixed to a single narrow band.
Solution Approach 2:
The patent changes the operational parameters of the imaging system by varying the wavelength band selection, bandwidth width, and integration time based on detection requirements. By dynamically adjusting these parameters, the system can optimize the signal-to-noise ratio for different gas concentrations and environmental conditions, achieving high contrast imaging without being overly sensitive to component noise.
3Device complexity
If uncooled thermal imaging devices are used, then device complexity and cost are reduced, but the sensitivity to detect low gas concentrations is insufficient due to high noise contribution
Solution Approach 1:
The patent segments the infrared detection into multiple narrow wavelength bands, which allows uncooled detectors to achieve effective gas detection by concentrating signal energy into specific spectral channels. This segmentation approach enables uncooled devices to overcome their inherent noise limitations by distributing the detection task across multiple spectral regions, thereby achieving practical gas detection sensitivity without complex cooling systems.
Solution Approach 2:
The patent applies partial action by using uncooled detectors with moderate sensitivity and compensating through spectral filtering and signal processing. Rather than requiring excessive cooling to achieve low noise, the system uses moderate cooling (or no cooling) combined with narrowband filtering and multi-band spectral analysis to achieve the necessary detection sensitivity for practical gas monitoring applications.
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
This approach enhances the sensitivity and contrast of gas detection, allowing for the visualization of smaller gas concentrations and reducing noise interference, thereby improving the accuracy of gas quantification in thermal imaging.
Implementation Method 1
a thermal imaging device, e.g. in the form of a thermography arrangement or an infrared IR camera, is provided to capture infrared (IR) image data values, representing infrared radiation emitted from an observed scene
Implementation Method 2
gas imaging may be based on the difference in absorption or transmission of infrared radiation in different wavelength bands
Data Source
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AI summary
A method and a system to quantify gas in a thermal imaging device, said method comprising obtaining a gas-absorption-path-length image as a scene difference infrared image based on a gas infrared image and a scene background infrared image substantially depicting the same scene and generating a quantified scene difference infrared image based on said scene difference infrared image and a predefined gas-quantifying relation.