Abstract: The invention relates to a color display device comprising a chromatic dispersive grating and an active matrix possibly of liquid crystal type. This device moreover comprises a matrix of spherical microlenses, the shape of the cross section of the microlenses being such that it makes it possible to compensate for the spreading of the R G B colored beams by virtue of the use of a dispersive grating, and hence to make best use of the circular aperture of projection objectives.

Abstract: A back projection device comprises an image generator (GI), an onward reflection mirror (MR) and at least one optical component (OM) capable of reflecting certain types of light beams almost entirely and reflecting certain other types of light beams almost entirely, said component being located in the proximity of a screen (E). The selection of optical behavior of the component (OM) may be done as a function of the polarization of the light beam, or else also as a function of its orientation with respect to said component (OM). Application: displays.

Abstract: This invention concerns chromatic light separators, and is particularly intended to reduce their dimensions. A chromatic separator in accordance with the invention contains at least two selective wave length mirrors. According to one characteristic of the invention, the two selective mirrors are nested holographic mirrors. The invention is particularly suitable for three-color rear-projection type picture projectors using liquid crystal screens.

Abstract: A three-color image projector, of the type using several colored light beams with primary colors, with improved luminous efficiency. The projector employs spatial rather than temporal beam modulation. The projector includes a generator producing light in the three spectral bands corresponding to the primary colors (red, green, blue). The generator has at least two light sources (S1, S2), one of which produces multi-spectral band light, and the other is a monochromatic source. By comparison with the prior art, where the white light is produced by a single source, this arrangement avoids, in particular, the elimination of a significant quantity of lumens in the excess primary color.

Abstract: A color display device comprises a source of light simultaneously emitting several ranges of chromatic components and a spatial light modulator comprising several dots, each dot comprising at least one sub-pixel per range of chromatic component to be displayed. Between the light source and the spatial light modulator there are provided at least one chromatic separator angularly separating the light of the different chromatic range along different directions, a lens focusing the light of the different chromatic ranges at distinct points or along distinct lines contained in a determined plane, at least one spatial filter located along this determined plane and selectively filtering the light of the different chromatic ranges, and an array of lenses, each enabling the focusing of the light of each chromatic range substantially on a sub-pixel.

Abstract: Disclosed is a separator of polarizations comprising a Bragg grating gripped between two plates comprising input and output faces in the form of steps. The advantages of the device are that it is light and compact.