Light emitting diodes (LED) have been increasingly used as light sources for projection display. LEDs have numerous
advantages as a light source for these applications especially when used with a digital micro-mirror spatial light
modulator such as the device offered by Texas Instruments. LEDs create an expanded color gamut, they can be
modulated at very high rates (thus, eliminating the need for a color wheel), and they last longer than other light sources.
One disadvantage they have is the luminous output is lower than would be desired for most front projection applications.
Smaller pocket projectors have used the LED sources successfully, but the luminous output is limited to between 25 and
100 lumens. One of the areas of light loss in the illumination system is in the multiplexer that combines the three
colored LEDs into a coaxial illumination beam. In this paper, this loss is quantified and an alternate multiplexer design