Flat-panel picture display device comprising a picture display panel for modulating the state of polarization of polarized light coupled into said panel in conformity with a picture to be displayed. The light is polarized by means of a reflective polarizer which is integrated or not integrated with the picture display panel. At least a part of the picture display panel functions as an optical waveguide, notably for the beam component b.sub.2 having the state of polarization which is not suitable for modulation. An analyzer is present at a first surface of the picture display panel. The polarizing means in the form of a reflective polarizer are present at a second surface of the picture display panel, which surface is located opposite the first surface. A light-directing system is present at the surface of the polarizer remote from the picture display panel, which system is used for sending the light leaving the picture display panel at this surface without contributing to the formation of the image to the picture display panel again so that it will as yet have a chance of being converted into light having the desired state of polarization.