Abstract: The present invention relates to light sensors for measuring light characteristics. In particular, the present invention relates to a light directionality sensor that is capable of measuring light characteristics such as the light direction, light collimation, and light distribution. According to a first aspect of the present invention there is provided a light directionality sensor comprising a photo-sensor (2), comprising a plurality of photo-sensitive elements (3), and a plurality of light-absorbing light selecting structures (1) arranged on the photo-sensor so as to form an array of light-absorbing light selecting structures. In the array of light-absorbing light selecting structures, a succession of at least some of the light-absorbing light selecting structures has varying structural characteristics.

Abstract: The present invention relates to light sensors for measuring light characteristics. In particular, the present invention relates to a light directionality sensor that is capable of measuring light characteristics such as the light direction, light collimation, and light distribution. According to a first aspect of the present invention there is provided a light directionality sensor comprising a photo-sensor (2), comprising a plurality of photo-sensitive elements (3), and a plurality of light-absorbing light selecting structures (1) arranged on the photo-sensor so as to form an array of light-absorbing light selecting structures. In the array of light-absorbing light selecting structures, a succession of at least some of the light-absorbing light selecting structures has varying structural characteristics.

Abstract: The electric lamp comprises a lamp vessel (1) which is transparent to visible light and which accommodates a light source (2). The lamp vessel (1) is covered with a combination of a light-absorbing medium (6) and an optical interference film (5) comprising layers of alternately a first layer of a material with a comparatively high refractive index and a second layer of silicon dioxide. According to the invention the maximum reflection Rmax of the interference film (5; 15) lies in the range from 0.50?Rmax?0.90 and in that the variation in the reflection R of the interference film (5; 15) in the wavelength range from 400???690 nm ranges from 0.0 to Rmax in order to obtain an overall color neutral appearance. In operation, the electric lamp according to the invention emits colored light in the transmission mode and has a substantially color-neutral appearance in the off state.

Abstract: An X-ray optical diaphragm (3; 4) which is provided with at least one passage opening (3a; 4a) for rays is constructed in such a manner that the edge zone (9; 10) of the X-ray optical diaphragm (3; 4) which faces the passage opening (3a; 4a) is angulated at least partly relative to the direction of propagation (7) of the rays.

Abstract: The electric lamp comprises a lamp vessel (1) which is transparent to visible light and accommodates a light source (2). The lamp vessel (1) is covered with a combination of a light-absorbing medium (6) and an optical interference film (5) comprising layers of alternately layers of silicon dioxide and layers of a material with a comparatively high refractive index (e.g. ZrO2). According to the invention, the reflection R of the interference film (5) changes from 0.60?R?0.95 to 0.40?R?0.65 with a step ?R in the range 0.2??R?0.45, in a wavelength range 0.95×?tr???1.2×?tr. In operation, the electric lamp according to the invention emits colored light in the transmission mode and has a substantially color-neutral appearance in the off state.

Abstract: An X-ray optical diaphragm (3; 4) which is provided with at least one passage opening (3a; 4a) for rays is constructed in such a manner that the edge zone (9; 10) of the X-ray optical diaphragm (3; 4) which faces the passage opening (3a; 4a) is angulated at least partly relative to the direction of propagation (7) of the rays.

Abstract: Generally known conventional X-ray tubes include a window opening which is covered by an X-ray transparent X-ray window which is usually made of beryllium. A significant absorption of X-rays of comparatively long wavelength, for example of the order of magnitude of from 1 nm to 10 nm, occurs in such windows. According to the invention, a bundle of X-ray conducting capillary tubes (46) is connected to the window opening of the X-ray tube, the other end (48) of the bundle being provided with a very thin X-ray window (50) which seals the interior of the capillary tubes (46), being in vacuum contact with the vacuum space of the X-ray tube, from the environment in a vacuum tight manner.

Abstract: To obtain a monotonic transmission/voltage characteristic curve in a reflective display having a small twist angle, the polarizer in a cell with crossed polarizer and analyzer is arranged parallel to the dividing line of the directions of orientation (23, 24) determining the twist angle .alpha., the cell being optimized for .alpha. and d..DELTA.n.

Abstract: By a suitable choice of a retardation foil with a specific value of .DELTA.n (.lambda.) it is possible to make the transmission/voltage characteristic curves for, for example, red, green and blue light extend parallel in an ECB display. The same type of display can then be used for modulating three colors, with modulation voltages shifted for each color.

Abstract: A liquid crystalline color display cell comprises two transparent, parallel substrate plates, 1, 2 (FIG. 1), a seal 3 and a liquid crystalline cell medium 5 which is present between the plates and the ring. The cell medium contains a dichroic, UV light-absorbing substance. Both substrate plates are provided with electrodes 6, 7 and the substrate plate are provided on the viewing side with a layer 9 of phosphors which emit colored light under the influence of UV light.

Abstract: A display cell which contains a liquid crystalline compound having a tilted orientation and a tilt angle of 8.degree.-50.degree., in which an orientation layer is used of a cyclo-aliphatic polyether.

Abstract: A liquid crystal display device comprises two supporting plates which are kept spaced apart and the facing surfaces of which comprise a pattern of line electrodes and column electrodes, respectively, which form a matrix of display cells. A mixture of a nematic liquid crystal with a cholesteric addition is present between the supporting plates. The mixture has a positive dielectric anisotropy and a natural pitch p such that the ratio d/p has a value between 0.6 and 0.9. The surfaces comprise an orientation layer to provide a progressive molecular twist .PHI. of the liquid crystal molecules (director) across the layer thickness d of greater than 1.2.pi. and less than 1.7.pi. radians with the director assuming an angle of tilt between 0.degree. and 7.degree. at one surface and an angle of tilt between 5.degree. and 70.degree. at the other surface. Below a field strength E.sub.1 the display cells are in a first stable state and above a field strength E.sub.