The thermal mirror needs to selectively reflect infrared while being transparent to visible light, and it needs to bounce radiation back and forth, which requir

The thermal mirror needs to selectively reflect infrared while being transparent to visible light, and it needs to bounce radiation back and forth, which requires a certain geometry. The novelty of this paper is creating a big flat filament sandwiched between high-temperature plates that reflect infrared and can be deposited as layered coatings.