Multifunction mono-block optical system in PMMA for collimating four individual LED sources with a concentration pyramid and an integrated mixing and homogenization light guide. This device collects the light emitted by four separate RGBW light sources. The light thus collected is concentrated into the pyramid and then sent to the light guide which mixes and homogenizes the four light sources. The multi-faceted output surface of the light guide ensures a perfect colour mix and helps to project a homogeneous image. (Patent FR 2943801A)