Methane leak detection by tunable laser spectroscopy and mid-infrared imaging

Area of Science:

• Spectroscopy and Imaging Technologies
• Environmental Monitoring and Sensing
• Gas Leak Detection Systems

Background:

• Mid-infrared imaging combined with tunable laser spectroscopy (TLS) offers sensitive gas leak detection.
• Current methods require close proximity for accurate methane leak quantification.
• Developing standoff detection methods is crucial for industrial safety and environmental monitoring.

Purpose of the Study:

• To demonstrate standoff methane leak detection using tunable laser spectroscopy and mid-infrared imaging.
• To achieve sensitive and quantitative visualization of methane leaks at a distance.
• To establish a calibration-free method for leak concentration determination.

Main Methods:

• Utilized an interband cascade laser at 3270 nm wavelength for methane absorption.
• Employed mid-infrared imaging with an infrared camera for spatial visualization.
• Applied direct absorption spectroscopy (DAS) for gas plume localization and quantification.
• Leveraged the HITRAN database for pixelwise concentration determination.

Main Results:

• Achieved visualization of methane leakage rates down to 2 ml/min.
• Demonstrated high frame rates up to 125 Hz for dynamic leak monitoring.
• Obtained pixelwise sensitivities of approximately 1 ppm*m.
• Enabled calibration-free, localized concentration measurements within a single image.

Conclusions:

• The developed active optical imaging concept provides a powerful tool for sensitive and quantitative standoff methane leak detection.
• This method allows for rapid, accurate, and localized assessment of methane emissions.
• The technique holds significant potential for industrial safety, environmental monitoring, and fugitive emission control.