Tunable Diode Laser Methane Imaging Through Windows
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Solution Overview
Problem
Current methane detection technologies face challenges in providing reliable, cost-effective, and safe standoff detection methods that can accurately determine gas concentration and location through windows, especially in scenarios requiring frequent and low-maintenance operation.
Innovation Solution
The development of a laser-based imaging system that uses single wavelength lasers to detect methane by modulating light sources between on-resonance and off-resonance states relative to the absorption spectrum of methane, enabling accurate concentration determination and location identification through windows with minimal maintenance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If passive optical imaging is used for standoff detection, then detection distance is improved, but measurement precision and reliability deteriorate
Solution Approach 1:
The patent combines active optical sensing (TDLAS) with imaging capabilities to create a system that provides both standoff detection distance and precise concentration measurement. The active laser source enables the system to achieve both long detection distance and high measurement precision simultaneously by using tuned diode lasers that interact with gas molecules over extended path lengths while maintaining sensitivity through imaging detection.
Solution Approach 2:
The system changes the optical parameters by using tunable diode lasers that can be adjusted to specific absorption wavelengths of target gases. This parameter tuning allows the system to optimize both detection distance and concentration precision by matching laser wavelengths to gas absorption lines, enabling accurate measurements at standoff distances.
2Measurement precision
If TDLAS is used for standoff and through-window sensing, then measurement precision is improved, but device cost worsens
Solution Approach 1:
The patent employs cost-effective tunable diode laser components and commercial off-the-shelf imaging detectors to reduce system cost while maintaining measurement precision. By using accessible technology components and optimizing the optical path through window materials, the system achieves precise gas detection at lower cost compared to traditional expensive standoff sensing systems.
3Ease of manufacture
If hand-held FID is used for gas detection, then device cost is reduced, but operator safety worsens due to direct contact requirement
Solution Approach 1:
The patent replaces the mechanical contact-based FID detection method with an optical detection system. The laser-based optical sensing eliminates the need for physical contact with the gas sample, allowing operators to detect gas concentrations from a safe distance while maintaining cost-effectiveness through the use of accessible optical components and imaging technology.
4Reliability
If passive optical imaging is used for large leak detection, then detection capability is improved, but maintenance requirements worsen
Solution Approach 1:
The system incorporates self-diagnostic and self-calibration capabilities through the use of stable laser wavelength references and built-in calibration gas options. The passive optical imaging components require minimal maintenance while maintaining reliable large leak detection capability, as the system can self-correct for environmental variations and component aging through reference measurements.
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 achieves accurate methane detection at explosive levels (4-15%) from a safe standoff distance, is cost-effective, and requires infrequent maintenance, making it suitable for first responders and widespread use.
Implementation Method 1
modulating the light source between an on-resonance state, relative to the absorption spectrum of the target gas, and an off-resonance state, relative to the absorption spectrum of the target gas
Implementation Method 2
An imaging device is positioned relative to the area of space such that the imaging device receives reflected light from the area of space, the imaging device configured to form an image from the reflected light showing the presence or absence of the target gas
Data Source
AI summary
A system and method indicate capability for detecting methane leaks inside buildings. This approach provides the ability to detect methane behind high efficiency coated windows and can extract methane concentration (rather than concentration-path length product CL). Lock-in imaging technologies can facilitate lower laser transmitter power. A field deployable, hand held prototype sensor for use in remote sensing a appropriate standoff distances can support operational testing. Distance infrared imaging of methane is feasible. Fully characterized real time image of a methane cloud offers operational advantages in accuracy and safety as compared to current sensors.