Abstract: The application relates to a single-polarizer reflective bistable twisted nematic (BTN) liquid crystal display device comprising a liquid crystal layer of thickness d, birefringence ?n and retardation ?nd, said liquid crystal layer being situated between two substrates and between a polarizer and a reflector, said liquid crystal layer in the absence of an applied electric field having two stable uniformly twisted textures, the twists of the two stable textures differing by an angle being equal mainly to 180°, and at least one compensation layer positioned between said polarizer and said reflector, said compensation layer being composed of at least one birefringent film, said birefringent film having an optical anisotropy defined by three characteristic refractive indices nx, ny, nz, along three corresponding axis x, y, z of index ellipsoid, x and y being situated inside the substrates plane, nx and ny being called in plane indices, with nx?ny, x being called slow axis, and z being perpendicular to the substra

Abstract: A device nematic liquid crystal display device has two stable states corresponding to two liquid crystal molecule textures whose torsion differs by 150° to 180° in terms of absolute value. The device includes two polarizers (10, 40), one (10) of which is placed on the observer side, the other (40) being placed on the opposite side of the liquid crystal cell. The orientation of the two polarizers is offset by a value which is equal to the rotatory power of the cell+/??/2, the rotatory power corresponding to the most twisted texture effect.

Abstract: The application relates to a single-polarizer reflective bistable twisted nematic (BTN) liquid crystal display device comprising a liquid crystal layer of thickness d, birefringence ?n and retardation ?nd, said liquid crystal layer being situated between two substrates and between a polarizer and a reflector, said liquid crystal layer in the absence of an applied electric field having two stable uniformly twisted textures, the twists of the two stable textures differing by an angle being equal mainly to 180°, and at least one compensation layer positioned between said polarizer and said reflector, said compensation layer being composed of at least one birefringent film, said birefringent film having an optical anisotropy defined by three characteristic refractive indices nx, ny, nz, along three corresponding axis x, y, z of index ellipsoid, x and y being situated inside the substrates plane, nx and ny being called in plane indices, with nx?ny, x being called slow axis, and z being perpendicular to the substra

Abstract: The invention relates to a nematic liquid crystal display having two stable states, without an electric field, obtained by anchoring break, characterized in that it comprises two polarizers (10, 40), one (10) of which is placed on the observer side, the other (40) being placed on the opposite side of the liquid crystal cell whereby the latter is at least partially reflecting in order to define a reflective mode or transflective mode. The orientation of the two polarizers (10, 40) is offset by a value which is equal to the rotatory power of the cell at approximately +/?30°.

Abstract: A device nematic liquid crystal display device has two stable states corresponding to two liquid crystal molecule textures whose torsion differs by 150° to 180° in terms of absolute value. The device includes two polarizers (10, 40), one (10) of which is placed on the observer side, the other (40) being placed on the opposite side of the liquid crystal cell. The orientation of the two polarizers is offset by a value which is equal to the rotatory power of the cell±n/2, the rotatory power corresponding to the most twisted texture effect.

Abstract: The invention relates to a nematic liquid crystal display having two stable states, without an electric field, obtained by anchoring break, characterized in that it comprises two polarizers (10, 40), one (10) of which is placed on the observer side, the other (40) being placed on the opposite side of the liquid crystal cell whereby the latter is at least partially reflecting in order to define a reflective mode or transflective mode. The orientation of the two polarizers (10, 40) is offset by a value which is equal to the rotatory power of the cell at approximately +/?30°.

Abstract: A display device comprising a liquid-crystal cell element (20) placed between two polarizers (23, 28) comprising at least one optical structure for compensating for the variations in birefringence of said liquid crystal according to the viewing angle. The optical compensation structure comprises at least one oblique-axis film (25, 26) of polymerized liquid-crystal type suitable for at least partly compensating for the undesirable effects of the natural birefringence of the liquid crystal, combined with a volume hologram (24, 27) of small retardation suitable for improving the compensatability of said film.

Abstract: A document includes at least one drawing or data produced, for example, by printing. In addition, this document includes a hologram representing part of the document. The hologram of this document is recorded using a system including a prerecorded or electrically controllable optical modulator in which the image of at least part of the document is recorded. This modulator is designed to be combined with a layer of photosensitive material. A first reference wave illuminates the layer of photosensitive material. A second wave incident on the modulator and giving rise to a third object wave is also transmitted to the layer of photosensitive material in order to interfere with the reference wave in this layer.

Abstract: A document includes at least one drawing or data produced, for example, by printing. In addition, this document includes a hologram representing part of the document. The hologram of this document is recorded using a system including a prerecorded or electrically controllable optical modulator in which the image of at least part of the document is recorded. This modulator is designed to be combined with a layer of photosensitive material. A first reference wave illuminates the layer of photosensitive material. A second wave incident on the modulator and giving rise to a third object wave is also transmitted to the layer of photosensitive material in order to interfere with the reference wave in this layer.

Abstract: A document includes at least one drawing or data produced, for example, by printing. In addition, this document includes a hologram representing part of the document. The hologram of this document is recorded using a system including a prerecorded or electrically controllable optical modulator in which the image of at least part of the document is recorded. This modulator is designed to be combined with a layer of photosensitive material. A first reference wave illuminates the layer of photosensitive material. A second wave incident on the modulator and giving rise to a third object wave is also transmitted to the layer of photosensitive material in order to interfere with the reference wave in this layer.

Abstract: A display device comprising a liquid-crystal cell element (20) placed between two polarizers (23, 28) comprising at least one optical structure for compensating for the variations in birefringence of said liquid crystal according to the viewing angle. The optical compensation structure comprises at least one oblique-axis film (25, 26) of polymerized liquid-crystal type suitable for at least partly compensating for the undesirable effects of the natural birefringence of the liquid crystal, combined with a volume hologram (24, 27) of small retardation suitable for improving the compensatability of said film.

Abstract: Color display system, which includes an electrooptic modulation screen (LCD) and in which a chromatic modulator (RC) is provided between the multiple-wavelength light source (S, C) and the screen (LCD). This chromatic modulator modulates a wavelength or a restricted range of wavelengths of the source in order to adjust the saturation of the various primaries transmitted to the screen as well as to effect colorimetric balance. Applications include liquid-crystal color displays.

Abstract: A polarization splitter which includes a splitting medium lying between two transparent elements of defined indices. The splitting medium includes a periodic structure of layers of materials of different indices and having a period which is small compared with the wavelength of an incident beam so as to form a uniaxial birefringent medium of optical axis perpendicular to the plane of the periodic structure. The two transparent elements are made of a material of index approximately equal to the ordinary index (no) of the periodic structure.

Abstract: A holographic projection screen for large screen projection and back projection with a liquid crystal projector. The screen includes at least one layer made of a photosensitive material in which at least one index grating may be recorded by an interference of an optical recording wave with an optical object wave. The thickness of the layer is equal to or greater than n0&Lgr;2/2&pgr;, where n0 is the average index of the photosensitive material, &Lgr; is the average spacing of the index grating and &lgr; is the recording wavelength.

Abstract: A compact illumination device intended especially for illuminating an active matrix in a monochromatic or trichromatic display device. This device includes a source and collimating device in order to deliver a lighting direction from the source along a direction (Dy) and two optical components (M1) and (M2) which anamorphose the lighting in a direction parallel to the direction (Dy) and in a direction (Dz) perpendicular to the direction (Dy), respectively. These components may typically be of the holographic grating type operating in transmission or in reflection.

Abstract: A display device including an illuminating source which emits radiation and a spatial light modulator illuminated by the radiation. The modulator includes a matrix of N.times.M elementary pixels (X.sub.i,j) of dimensions d.sub.N .times.d.sub.M, the pixels X.sub.i,j and X.sub.1+i,j being separated by a spacing p.sub.N. The radiation is collimated in each pixel. The spacing p.sub.N is greater by at least an order of magnitude than the dimension d.sub.M. The display may be used as a flat television screen.

Abstract: An illumination device comprises a light source coupled to a waveguide. the waveguide comprises a diffracting element capable of diffracting emergent light rays coming from the source, in a direction substantially perpendicular to the surface of the waveguide. A device of this kind is particularly well-suited to transmissive display screens of the liquid crystal display screen type. It can generate a highly collimated, polarized light.

Abstract: Invention concerning the therapeutic use of tetracyclic derivatives and their pharmaceutically acceptable salts having the following general formula: ##STR1## in which, independently of the other: X is a carbon or nitrogen atom,T is a carbon or nitrogen atom,L is an oxygen atom or ketone functional protective group,R.sub.1 is an atom of hydrogen, an atom of halogen, or a C.sub.1 to C.sub.5 alkyl radical,R.sub.2 is a hydrogen atom, a halogen atom, a nitro radical, or a C.sub.1 to C.sub.5 alkyl radical,n and m are equal to 0 or to 1, but not independently of the other, so that if n is equal to 1, then m is equal to 0, and if n is equal to 0, then m is equal to 1.

Abstract: This optical filtering device includes a dichroic separator on the path of a light beam to be processed. According to the invention, it also includes a holographic filtering device situated in series with the separator on the path of the same beam. The holographic device can be oriented so as to adjust the angle of incidence of the beam and hence adjust its range of filtering wavelengths.

Abstract: The color display device includes at least a light source which emits at least two primary wavelengths and an array of holographic lenses (HL). Also included is a spatial light modulator (LCD) which includes one picture element (pixel) for each holographic lens with each pixel including one subpixel for each wavelength to be displayed. Each of the holographic lenses disperses the various wavelength and focuses each of them into one of the subpixels. The structure allows for a single lens structure for the various wavelengths.