Using a fly's eye integrator in efficient illumination engines with multiple light-emitting diode light sources

High brightness light emitting diodes (LEDs) become a serious alternative for ultrahigh performance lamps in projection displays. We focus on the illumination part of a LED projection engine. We discuss the problem of using several LED light sources for each primary color. In critical applications, the use of several light sources for each color has important benefits. It increases the possible light output to the screen and makes it possible to design a system that is tolerant for failures of one of the LEDs. Therefore, we need an optical system that is both efficient and is able to produce a uniform light beam if one of the LEDs fails. We show that our illumination engine using a fly's eye integrator meets these requirements, using ray-tracing simulations of the engine. An efficient optimization method based on the simplex method [R. J. Koshel, Opt. Lett. 30, 649 - 651 (2005)] was developed to design the LED collimation reflective device with collection efficiencies up to 95%. The lens systems in the engine were designed with the same method. This results in a total system efficiency of 77%. (c) 2007 Society of Photo-Optical Instrumentation Engineers.