Projection display device which comprises a light source for generating a light beam, integrator means for converting the light beam into a uniform rectangular beam, modulator means for modulating the rectangular light beam with the information to be displayed, and projection means for projecting the modulated rectangular light beam on a display plane. The integrator means comprises a triangular prism and an integrator device positioned between the light source and the triangular prism. The triangular prism is arranged for total internal reflection on at least one or more of its non-folding planes or, for best optical performance, on all of its non-folding planes.
