An optical projector is described that orients its optics engine preferably vertically within an enclosure that is higher than it is wide or deep. The invented optics engine uses a prismatic cube for color separation or beam splitting, with the prismatic elements within the cube being secured within a durable frame that mounts the three color light valves, e.g. twisted nematic liquid crystal display (LCD)-type shutters, in a predefined position and orientation relative to the prismatic cube. In order to improve image quality and brightness, especially of the notoriously difficult-to-reproduce green color, red and blue beams are S polarized, as is conventional, but the green beam is P-polarized. The invented optical projector preferably includes a frame having a footing portion for resting on a support surface, a light source high above the footing portion, optical convolution structure downstream from the light source for reverse-bending downwardly flowing light from the source, light modulation structure near the reverse bend region for infusing the light with image information and for directing modulated light upwardly in a projectable, image-containing stream of light and outward-projection directing structure high on the frame for receiving and outwardly directing such stream of light.