Prism film is well known in the display industry for adding brightness and efficiency to backlights used with LCDs. Faceted films are used to redirect light such as a Fresnel lens used to focus or spread light. In both cases the structure is made up of polished microstructure facets that act like very small prisms to bend light in certain directions. The size ranges from a few hundred micrometers to sub-micron. They are typically originated using Diamond Turned machining methods but can also be created using laser ablation or lithographic techniques.