Color display device having single illuminating system

A display device is disclosed herein. The display device includes a condenser unit, an illumination lens system, an optical modulation system, a filter system and a projection system. The condenser unit converges polarized light output from a plurality of light sources, and outputs the converged polarized light. The illumination lens system converts the polarized light into linear parallel light. The optical modulation system produces diffracted light beams having a plurality of diffraction orders by optically modulating the polarized light. The filter system passes some of the diffracted light beams having desired orders therethrough. The projection system focuses the diffracted light beams passed through the filter system, and projects the focused diffracted light beams onto a screen.