Making invisible gas leaks visible

For The New York Times, Jonah M. Kessel and Hiroko Tabuchi went to oilfields in Texas with an infrared camera to look for methane leaks.

Okay, important topic here, and the contrast between regular photograph and infrared video is alarming, but I may have been drawn to the methodology at the end:

To create images of methane emissions in the Permian Basin, The Times used a custom-built FLIR camera that converts infrared energy into an electronic signal to create moving pictures. The camera’s filter allows infrared wavelengths between 3.2 to 3.4 micrometers on the electromagnetic spectrum to pass through to the sensor.

To visualize gas, the camera uses helium to cool down the sensor to the temperature of liquid nitrogen, around minus 200 degrees Celsius. Unlike traditional photography lenses, which are glass, the infrared images were created using metal lenses made from germanium, which is transparent at infrared wavelengths.