Described is an improved optical engine including dichroic mirror elements that have opposing substantially parallel planar surfaces, with the mirror elements positioned and oriented selectively and simultaneously to split a first light beam incident upon one of the opposing surfaces and to recombine modulated second and third beams incident upon the other of the opposing surfaces, wherein a beam of light emerging from the one of the opposing surfaces contains both modulated and unmodulated color components. Preferably, the invented optical engine takes the form of concentric squares, when viewed normal to a plane in which its optical elements lie, wherein the interior square contains plural dichroic elements and the exterior square contains plural turning mirror elements. The optical engine may be used along with conventional other optical elements including, for example, white light sources, turning mirrors, liquid crystal shutters and optical output stacks, to render a pixel-modulated tricolor projector. Preferably, coated plate glass dichroic elements within the invented image provide dual functionality with respect to various of the three colored light beams, i.e. splitting two unmodulated color beams incident upon a first surface thereof and reflecting one of them while simultaneously combining the reflected one of them with a modulated third color beam incident upon an opposite surface thereof to produce a light beam that emerges from the first surface that contains both modulated and unmodulated color components. Pupil and image astigmatism correction are performed by plate assemblies positioned in the input white and output tricolor paths of the engine.