Mixing rods are used in illumination systems to provide a uniform output. The use of separate sources, especially RGB
LEDs, has renewed interest in the use of mixing rods. This paper describes some of the special issues that arise with the
use of RGB LEDs. Issues discussed include die layout for RGB LED arrays, straight round mixers with ripples and
RGB LEDs, the use of a diffusers with mixers, and the use of a square to rectangular mixer with ripples to circularize the
mixer's angular output.