The present embodiments provide methods, systems and apparatuses for use in generating a mixed output light beam. In some embodiments, apparatus comprises a mixing cavity (10) and a plurality of injection sources (2,22,32). The mixing cavity includes a plurality of input ports (11,12,13), an output port (15), and a reflective interior. The injection sources optically align with the input ports of the mixing cavity, and each comprise a light source optically aligned with injection optics such that the injection optics direct light from the light source into the input ports of the mixing cavity. In some implementations, the injection sources can include a have semicircular cross-section. Some implementations include etendue-squeezing reflector (3) positioned about a portion of the light source to be directed to the injection optics. The injector sources can further provide interference filtering (4) to provide light beams of defined wavelength ranges to the mixing cavity.