This material could camouflage objects from infrared cameras
Hotter objects typically glow brighter than cooler ones, making them stand out in infrared images. But a newly designed coating bucks the rule that hotter equals brighter. For certain wavelengths of infrared light, the material’s brightness doesn’t change as it warms, researchers report December 17 in Proceedings of the National Academy of Sciences. Made of samarium nickel oxide, the thin coating “hides temperature information of surfaces from infrared cameras,” and could therefore be used as a privacy shield, says applied physicist Mikhail Kats of the University of Wisconsin–Madison. A basic rule of physics known as the Stefan-Boltzmann law states that the brightness of the thermal radiation emitted by an object grows rapidly with increasing temperature. Turn up the heat on an electric stove, for example, and the coils get brighter. The same trend goes for invisible wavelengths of light, such as infrared. Infrared cameras measure how much thermal radiation objects emit in infrared wavelengths to estimate their temperatures. So if the normal link...