US Patent 7261418 Projection apparatus

A projection engine uses a first polarizing beam splitter (PBS) that substantially reflects light incident along a first input direction in a first polarization state and substantially transmits light incident in the first input direction in a second polarization state orthogonal to the first polarization state. The first PBS demonstrates an angularly dependent reflectivity for light in the second polarization state that is asymmetric about the first input direction. At least two imager devices are positioned to receive light reflected and transmitted by the first PBS respectively. The imager devices modulate the incident light with an image. The image light from the imagers is combined and projected.