Thermal imaging through hot emissive windows

It is not currently possible for an infrared camera to see through a hot window. The window’s own blinding thermal emission prevents objects on the other side from being imaged. Here, we demonstrate a path to overcoming this challenge by coating a hot window with an asymmetrically emitting infrared metasurface whose specially engineered imaginary index of refraction produces an asymmetric spatial distribution of absorption losses in its constituent nanoscale resonators. Operating at 873 K, this metasurface-coated window suppresses thermal emission towards the camera while being sufficiently transparent for thermal imaging, doubling the thermal imaging contrast when compared to a control window at the same temperature It is not currently possible for an infrared camera to see through a hot window. Now Ciril Samuel Prasad and colleagues report a metasurface-coated window which suppresses thermal emission towards an IR camera while being sufficiently transparent for thermal imaging.