Abstract: An illumination device for a display screen operable in an open-viewing mode B1 and a restricted-viewing mode B2 where light is emitted in a limited angular range. It includes a backlight emitting the limited-angular-range light, a plate-shaped light guide with large surfaces and narrow connecting sides in front of the backlight in a viewing direction. The light guide has outcoupling elements on the surfaces or within its volume, and is at least 50% transparent to backlight light. Outcoupling elements have a function surface for coupling out light guide light. Illuminants are arranged laterally of the narrow sides. The backlight is on and the illuminants off in mode B2, and the illuminants are on in mode B1. Some outcoupling elements have a structure causing scattering in a preferential direction that is stronger by a factor of at least 1.2 than in a direction perpendicular to the preferential direction, yielding anisotropic scattering.

Abstract: A display screen which can be operated in at least two operating modes, B1 for an unrestricted viewing mode and B2 for a restricted viewing mode, including a transmissive image rendering device which modulates light that is incident upon it for displaying image content and which can be operated in a first operating mode B1 for an unrestricted viewing mode and in a second operating mode B2 for a restricted viewing mode. The display screen includes an illumination device arranged behind the transmissive image rendering device and which can be operated in at least two operating modes B1 and B2. The illumination device emits light in an unrestricted viewing angle range in mode B1 and emits light in a restricted viewing angle range in mode B2. The display screen further includes a control for the transmissive image rendering device and the illumination device for switching between modes B1 and B2.

Abstract: A display screen including an image reproduction unit with a control unit and detector for detecting a translation of the image reproduction unit relative to an initial position and/or a rotation of the image reproduction unit relative to an initial orientation and/or for detecting an absolute or relative position of the image reproduction unit with respect to a reference system. The image reproduction unit changes, for a portion of its image surface, the relative luminance distribution curve for contents displayed thereon along a direction R which is selectable but fixedly oriented with respect to the image reproduction unit when a translation path detected by the detector relative to the initial position is above a threshold value and/or a detected angle of rotation relative to the initial orientation is above a respective threshold value and/or the absolute position or relative position with respect to a reference system is outside a tolerance.

Abstract: An optical element comprising a planar substrate with a first large surface functioning as a light-entrance surface, and a second large surface functioning as a light-exit surface. The optical element further comprises a liquid or skeleton matrix arranged between the first and second large surface, and electrophoretically or magnetophoretically movable particles that interact with light of one or several wavelengths or wavelength ranges.

Abstract: A method for influencing light propagation directions of a plurality of illuminated surfaces, comprising: arranging switchable absorbers on the light-exit side of the surfaces, such that light only exits through portions of the surfaces which are in front of the surfaces; switching on the absorbers for a first operating state so that a portion of the light emanating from the surfaces is absorbed, while the rest of the light exits at the surface portions of the light-exit side of the surface substrates at which no switchable absorbers are applied, resulting in light only being visible from a limited viewing angle which is defined by the shape of the switchable absorber, the shape of the surface, refractive index conditions in, and thickness of, the substrates of the surfaces; and switching off the absorbers for a second operating state so that light from the surfaces is visible from an unrestricted viewing angle.

Abstract: The invention relates to a switchable light filter (5), comprising a first optical element (1), in turn comprising a plurality of light-absorbing transition dipole moments, so that light, which is incident into the first optical element (1), is transmitted or at least partially absorbed as a function of its direction of incidence with respect to the first optical element (1) and its polarization state, means for optionally generating a first electric field (EF1) or a second electric field (EF2), a liquid crystal layer (3), onto which the first electric field (EF1) or the second electric field (EF2) acts, so that the transmission properties of the switchable light filter (5) differ between a first operating mode B1. The invention further discloses lighting devices and screen, which use an afore-described switchable light filter (5).

Abstract: An optical element including: a substrate with first and second large surfaces and a second; a plurality of opaque surfaces near or on the first large surface; in a first alternative, a plurality of surfaces near or on the second large surface which are switchable between an opaque state and a transparent state, or, in a second alternative, a plurality of chambers in the substrate which are filled with a fluid, wherein the fluid contains up to 30 volume percent of electrophoretically movable particles which absorb light and can be localized in two different states in the chambers by a variable electromagnetic field so that, in a first state the optical element limits the propagation directions of light which impinges on the light entry surface and in a second state, the optical element does not limit the propagation directions of light impinging on the light entry surface.

Abstract: An optical element including: a substrate with first and second large surfaces and a second; a plurality of opaque surfaces near or on the first large surface; in a first alternative, a plurality of surfaces near or on the second large surface which are switchable between an opaque state and a transparent state, or, in a second alternative, a plurality of chambers in the substrate which are filled with a fluid, wherein the fluid contains up to 30 volume percent of electrophoretically movable particles which absorb light and can be localized in two different states in the chambers by a variable electromagnetic field so that, in a first state the optical element limits the propagation directions of light which impinges on the light entry surface and in a second state, the optical element does not limit the propagation directions of light impinging on the light entry surface.

Abstract: A light guide which has two main faces, each having at least one surrounding edge; the main faces connected by lateral faces at the edges. The light guide includes three-dimensionally shaped light outcoupling elements on a main face and/or within the volume enclosed by the main and lateral faces. The outcoupling elements are distributed according to a predetermined pattern. Light coupled into the light guide propagates by total internal reflection unless entering or impinging on an outcoupling element and for outcoupling, one of the two main faces is preferred over the other. The outcoupling elements are divided into groups, each group being complementary to the other groups. Group members each have a common blaze angle and a common outcoupling property, which differ from those of the members of the other groups, which results in light being outcoupled with different angular distributions, thereby reducing visible artifacts.

Abstract: A two-dimensionally extensive optical element having a light entry side and a light exit side. The optical element includes alternating transparent first regions and second regions having materials with different first refractive indices and second refractive indices. The first refractive index is higher than the second refractive index. First layers and second layers which are opaque or are switchable to be opaque are arranged at the light entry surfaces and light exit surfaces of the second regions. When the layers are opaque, the propagation directions of light passing through the optical element are limited compared to layers which are switched to be transparent.

Abstract: A display screen which can be operated in at least two operating modes, B1 for an unrestricted viewing mode and B2 for a restricted viewing mode, including a transmissive image rendering device which modulates light that is incident upon it for displaying image content and which can be operated in a first operating mode B1 for an unrestricted viewing mode and in a second operating mode B2 for a restricted viewing mode. The display screen includes an illumination device arranged behind the transmissive image rendering device and which can be operated in at least two operating modes B1 and B2. The illumination device emits light in an unrestricted viewing angle range in mode B1 and emits light in a restricted viewing angle range in mode B2. The display screen further includes a control for the transmissive image rendering device and the illumination device for switching between modes B1 and B2.

Abstract: A method for the nondestructive inspection of a surface structure, including: preparing the surface structure; wetting a portion of the surface structure with a liquid, the variation in the thickness of the liquid above the portion of the surface structure being at most 50% of the maximum thickness of the liquid above the surface structure, so that the liquid forms a light guide which has, and is bounded by, the inverse shape of the surface structure at a first large surface and is bounded by air at a second large surface; coupling light into the light guide so that the inverse shape of the surface structure at the first large surface is impinged by light such that light coupled into the light guide is coupled out of the light guide via the second large surface; capturing an image of the light coupled out and; evaluating the captured image.

Abstract: A method for the nondestructive inspection of a surface structure, including: preparing the surface structure; wetting a portion of the surface structure with a liquid, the variation in the thickness of the liquid above the portion of the surface structure being at most 50% of the maximum thickness of the liquid above the surface structure, so that the liquid forms a light guide which has, and is bounded by, the inverse shape of the surface structure at a first large surface and is bounded by air at a second large surface; coupling light into the light guide so that the inverse shape of the surface structure at the first large surface is impinged by light such that light coupled into the light guide is coupled out of the light guide via the second large surface; capturing an image of the light coupled out and; evaluating the captured image.

Abstract: An illumination device for a display screen operable in an open-viewing mode B1 and a restricted-viewing mode B2 where light is emitted in a limited angular range. It includes a backlight emitting the limited-angular-range light, a plate-shaped light guide with large surfaces and narrow connecting sides in front of the backlight in a viewing direction. The light guide has outcoupling elements on the surfaces or within its volume, and is at least 50% transparent to backlight light. Outcoupling elements have a function surface for coupling out light guide light. Illuminants are arranged laterally of the narrow sides. The backlight is on and the illuminants off in mode B2, and the illuminants are on in mode B1. Some outcoupling elements have a structure causing scattering in a preferential direction that is stronger by a factor of at least 1.2 than in a direction perpendicular to the preferential direction, yielding anisotropic scattering.

Abstract: An optical element which can be utilized in various versions and implementations of switchable light filters having, in addition, polarization filters and/or other means for varying the polarization characteristics of light, for example, liquid crystal layers. A combination of switchable light filter and imaging display device makes possible a private viewing effect that can be switched on and off. The optical element comprises a first layer or a first layer and a plurality of further layers, each layer including a material with a plurality of light-absorbing transition dipole moments. At least in a first state, each transition dipole moment is oriented, with a tolerance of 10° at the maximum, parallel to a selectable preferential direction or fluctuates around it so that light which is incident in the optical element is transmitted or at least partially absorbed depending on its incident direction.

Abstract: A method for influencing light propagation directions of a light-emitting surface emitting light of a first wavelength range in a first direction and light of a second and wavelength range in a second direction. The wavelength ranges have a wavelength-dependent spectral radiance and differ in a peak wavelength. A switchable color converter is arranged in front of the light-emitting surface. The method includes the steps of a) deactivating the color converter for a first mode so that the second-wavelength range is transmitted and the first-wavelength range is absorbed, such that light from the light-emitting surface is only perceptible from the second direction, or b) activating the color converter for a second mode so that light of the first-wavelength range is converted into light of the second-wavelength range and light of the second-wavelength range is transmitted, such that light from the light-emitting surface is perceptible from both directions.

Abstract: A two-dimensionally extensive optical element having a light entry side and a light exit side. The optical element includes alternating transparent first regions and second regions having materials with different first refractive indices and second refractive indices. The first refractive index is higher than the second refractive index. First layers and second layers which are opaque or are switchable to be opaque are arranged at the light entry surfaces and light exit surfaces of the second regions. When the layers are opaque, the propagation directions of light passing through the optical element are limited compared to layers which are switched to be transparent.

Abstract: An optical element including a plate-shaped substrate with a light-entrance surface and a light-exit surface, a multiplicity of imaging elements formed on the light-exit surface and a multiplicity of diaphragms formed on the light-entrance surface. Each diaphragm includes a transparent geometric region in an opaque region. The optical element can be switched between two operating modes B1 and B2 such that some of the imaging elements change their focal length between values f1 and f2 and/or, some of the diaphragms change their aperture width and/or their position. Exactly one diaphragm is associated with each imaging element in mode B1 so that light passing through the diaphragm is imaged or collimated by the associated imaging element. Consequently, light arriving in the optical element through the diaphragms and then through the light-entrance surface has, after passing through the associated imaging elements in the two operating modes B1 and B2, different propagation angles.

Abstract: A method for influencing light propagation directions of a light-emitting surface emitting light of a first wavelength range in a first direction and light of a second and wavelength range in a second direction. The wavelength ranges have a wavelength-dependent spectral radiance and differ in a peak wavelength. A switchable color converter is arranged in front of the light-emitting surface. The method includes the steps of a) deactivating the color converter for a first mode so that the second-wavelength range is transmitted and the first-wavelength range is absorbed, such that light from the light-emitting surface is only perceptible from the second direction, or b) activating the color converter for a second mode so that light of the first-wavelength range is converted into light of the second-wavelength range and light of the second-wavelength range is transmitted, such that light from the light-emitting surface is perceptible from both directions.

Abstract: An optical element which can be utilized in various versions and implementations of switchable light filters having, in addition, polarization filters and/or other means for varying the polarization characteristics of light, for example, liquid crystal layers. A combination of switchable light filter and imaging display device makes possible a private viewing effect that can be switched on and off. The optical element comprises a first layer or a first layer and a plurality of further layers, each layer including a material with a plurality of light-absorbing transition dipole moments. At least in a first state, each transition dipole moment is oriented, with a tolerance of 10° at the maximum, parallel to a selectable preferential direction or fluctuates around it so that light which is incident in the optical element is transmitted or at least partially absorbed depending on its incident direction.