The TSTNTM (triple super twisted nematic) LCD is a successful method for obtaining color by stacking three panels, each of which subtracts out a primary color. Because the individual pixels of the three panels must line up to form one fully colored pixel, collimated light is needed. Incandescent lamps are easy to collimate, but are not as popular as fluorescent lamps in the display industry because of poorer efficacy, lifetimes, and color saturation. Fluorescent lamps are inherently diffuse sources that are difficult to collimate. By covering the inside of a hot cathode fluorescent lamp with a reflective MgO layer, small apertures can be made as bright as 50,000 foot lamberts. Individual lenses, centered on each aperture, can collimate these apertured sources.
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