Patent ID: 6976759

Claim:
A prism assembly which comprises an input prism, an output prism, and a polarizer between the input and output prisms, wherein: (A) the input prism comprises: (i) a first surface which receives polarized illumination light from an illumination system; (ii) a second surface which is configured and arranged to provide polarized illumination light to an imaging device and to receive modulated reflected light from the imaging device, wherein the first surface and the second surface are along a same side of the input prism; and (iii) a third surface which faces the output prism; (B) the output prism comprises: (i) a first surface which faces the third surface of the input prism; and (ii) a second surface which is configured and arranged to provide light to a projection lens to form a projected image; and (C) the polarizer: (i) is between the third surface of the input prism and the first surface of the output prism; and (ii) reflects light having a first polarization direction and transmits light having a second polarization direction; wherein the polarized illumination light has an optical path which comprises: (i) inward transmission through the first surface of the input prism; (ii) total internal reflection at the second surface of the input prism; (iii) outward transmission through the third surface of the input prism; (iv) reflection from the polarizer; (v) inward transmission through the third surface of the input prism; and (vi) outward transmission through the second surface of the input prism.