Illumination devices with improved color mixing optics are disclosed herein for mixing the colors produced by a multi-colored LED emitter module to produce uniform color throughout the entire beam angle of the output light beam, along with smoother edges and improved center beam intensity. Embodiments disclosed herein include a unique arrangement of multi-color LEDs within an emitter module, a unique exit lens with different patterns of lenslets on opposing sides of the lens, and other associated optical features that thoroughly mix the different color components, and as such, provide uniform color across the output beam exiting the illumination device. Additional embodiments disclosed herein include a unique arrangement of photodetectors within the primary optics structure of the LED emitter module that ensure the optical feedback system properly measures the light produced by all similarly colored emission LEDs.