In illumination systems, it is often necessary to get a structure that can have good performance on uniformity. Although light-emitting diodes (LEDs) are replacing conventional light sources in illumination systems, they have nonuniformity and a large view angle. In this paper, an LED illumination system has been designed that can use color sequential to replace the color wheel for projector and also can mix color to get the color you want. An optical element tapered light pipe is also used in this structure, and we investigate the mechanism of irradiance distribution. It assists in the design of light pipe for different applications. The efficiency is above 80% and the uniformity is better than 60%. The formation of irradiance distribution in the tapered light pipe is discussed, both analytically and numerically. The result of the simulation verifies that efficiency of this structure is well enough for the illumination of both car headlights and interior lighting. This illumination system also provides a good color-mixing effect that can replace arc lamps or fluorescent lamps.
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