US Patent 7431464 Projection display system with diffractive linear display device

A projection display system in which light use efficiency and image brightness are enhanced by collecting and using substantially all of the light that has been diffracted from a diffractive linear display device without loss of higher-order modes of diffracted light. The projection display system includes a light source, a linear light illumination system that transforms light emitted from the light source into a thin linear light, a diffractive linear display device that modulates the luminous intensity of the thin linear light by selectively diffracting the thin linear light, a mode selection optical system that selectively transmits or filters out the light diffracted by the diffractive linear display device according to the order of the diffracted light, a scanner that scans a linear image projected from the mode selection optical system, and a projection lens that enlarges and projects the image onto a screen.