The Science Behind Optical Gas Imaging

An optical gas imaging camera can be considered a highly specialized version of an infrared or thermal imaging camera. There is a lens, a detector, some electronics to process the signal from the detector, and a viewfinder or screen for the user to see the image produced by the camera. The detectors used for OGI cameras are quantum detectors that require cooling to cryogenic temperatures (around 70K or -203°C). Midwave cameras that detect gases such as methane commonly operate in the 3-5 μm range and use an indium antimonide (InSb) detector. Longwave cameras that detect gases such as sulfur hexafluoride tend to operate in the 8-12 μm range and use a quantum well infrared photodetector (QWIP).