Performance metrics & physics
Nanometre
A nanometre (nm) is one billionth of a metre, the unit used to express wavelengths of light and the size of nano-particles in modern ceramic window films.
Nanometre is the natural unit for the visible and near-infrared spectrum. Violet light is at 380 nm, red at 780 nm, NIR up to 2500 nm.
Nano-particles in ceramic films are typically 5–100 nm — small enough to not scatter visible light but large enough to interact with longer NIR wavelengths.
This scale matching is why nano-ceramic chemistry works. The particle size is engineered to be optically transparent to visible but opaque to IR.