It turns out that a single pixel can make a big difference when it comes to detecting gases that would otherwise go unnoticed to the naked eye.
“Despite methane gas being invisible to the eye, we have developed a method of color-coding this gas information and overlaying it onto a conventional camera image,” commented Dr. Graham M. Gibson proudly. He led the technical work in a study that was published in The Optical Society journal Optics Express recently that changes the way we see our world.
He continued by pointing out, “This allows the user operating the camera to look around, identify things and see an overlay of where the gas is present.”
A system for safety.
This infrared imaging system could offer low-cost, real-time detection of stray methane in oil and gas facilities, as well as pipelines. Leaks of methane which is the primary chemical in natural gas can be very hard to detect, and advances like this offer us a great way to keep an eye on a dangerous pollutant.
Dr. Graeme Malcolm OBE, CEO and Co-Founder of M Squared, the company that worked in close cooperation with the researchers said:
“One of the challenges from a commercial point of view has been translating infrared technology to bigger markets where price points are sensitive. This new technology could allow infrared imaging and sensing to become more readily available and help improve the environment by reducing gas losses in the oil and gas industry.”
A New Way To See
The system combines two different imaging technologies to produce a truly new way of detecting methane leaks.
The process starts with hyperspectral imaging projecting a series of infrared light patterns with a laser wavelength that is absorbed by methane. These patterns are made with a digital micromirror device, and reconstructed to create a picture which demonstrates where methane has absorbed the laser pattern.
The differences between the projected image and the reconstructed image will show if there is methane present.
A single-pixel camera is used to measure the light scattered from the scene, as traditional cameras don’t always exist in the wavelengths needed to detect methane, or are far too expensive for commercial applications.
With this system a single-pixel camera is key to enabling a commercial methane gas detection system to become a reality.
This system has no moving parts, and works in conjunction with a normal camera to give inspectors a real-time view of methane contamination. It also uses its own source of illumination, so it is far more likely to work under any circumstances, as opposed to existing systems that rely on the sun, or artificial light.
Dr. Nils Hempler, Head of Innovation at M Squared, expands on this advantage:
“For systems using passive illumination, darkness or rain will cause the signal reaching the imaging system to vary or be non-existent. An active illumination source is independent of environmental changes, including changes in temperature or light, and provides enhanced contrast and higher sensitivities.”
The researchers demonstrated that their system could visually identify methane gas leaking from a tube around 1 meter away from the camera using a capture speed of approximately 25 frames per second. It was also able to distinguish methane from other gases when they were in the same area.
“One of the things that we found is that we don’t necessarily need high-resolution images when detecting gas leaks,” notes Gibson. “A relatively fast frame rate on your camera provides more information about where the gas is leaking from than having very high-resolution images.”
This is a wonderful development that will allow further advances in the maintenance of oil and gas infrastructure. The team that authored this paper are hoping to use the same technology with other gases as well, and that is promising.