a polarization conversion system is located in the output light path of a projector . the pcs may include a polarizing beam splitter , a polarization rotating element , a reflecting element , and a polarization switch . typically , a projector outputs randomly - polarized light . this light is input to the pcs , in which the pcs separates p - polarized light and s - polarized light at the polarizing beam splitter . p - polarized light is directed toward the polarization switch on a first path . the s - polarized light is passed on a second path through the polarization rotating element , thereby transforming it to p - polarized light . a reflecting element directs the transformed polarized light along the second path toward the polarization switch . the first and second light paths are ultimately directed toward a projection screen to collectively form a brighter screen image in cinematic applications utilizing polarized light for three - dimensional viewing .