Windows let light, warmth and a view into rooms, but we don't always want all three of those at once. Researchers have embedded tiny reflective mini-mirrors in them and keep rooms comfortable all year round. The team used a precision laser to create a grooved microstructure on the surface of a film. Tiny mirrors, known as Compound Parabolic Concentrator (CPC) lenses, are then evaporated into the pores on the surface. The film can be applied to glass or inserted into double-glazed windows, where the array of mini-mirrors can then reflect sunlight into the room more efficiently, lighting up even the gloomiest corners. In their tests, the researchers say the smart window material managed a light incidence of 60 degrees and was able to divert 80 percent of the incoming light, spreading it out into the room almost horizontally. [Source]