Abstract: In a luminescent material which comprises a first component for luminescing red light under influence of incident optical radiation and a second component for luminescing in the spectral range from 520 to 560 nm, the second component includes a first phase of garnet crystallization system consisted of yttrium aluminate activated by trivalent cerium and determined by the general structural formula Y.sub.3-a Ce.sub.a Al.sub.5 O.sub.12, wherein 0.0003<a<0.1, and a second phase of hexagonal crystallization system of general structural formula La.sub.b Ce.sub.1-b Al.sub.11 O.sub.18, wherein O<b<1, and the second phase is present in an amount ranging from the amounts detectable by means of X-ray diffractometry to the double amount of the first phase.

Abstract: In a high-pressure gas discharge lamp, particularly a high-pressure sodium vapor lamp, comprising a tubular discharge vessel being made of a ceramic material and including electrodes and a filling and ceramic plug elements for closing the end regions of the discharge vessel, receiving a current lead-in connecting the electrode with an outer source of supply voltage, wherein at least one of the plug elements is built up with surface elements of different height levels and determining a cold chamber for receiving the metal additive, the distance between the surface of the metal additive and the current lead-in measured as length of the way determined on the surface elements is at least 4 mm.

Abstract: The invention relates to a high pressure sodium vapor lamp having improved color reproduction index, which has a discharge vessel (1) placed in an outer envelope (10) and at least a pair of electrodes (4,5) and a filling comprising of at least one additive material and a fill gas, as well as a pair of current conductors (6,7) for supplying current for the electrodes (4,5). The essence of the invention resides in that especially in the case of high pressure sodium vapor lamps of low output for the increasing of the color reproduction index filaments (2,3) are arranged at the ends and outside of the discharge vessel (1) and which during the entire operation of the discharge vessel (1) are connected in series therewith.

Abstract: The invention concerns a headlamp, the envelope of which is constituted internally by at least one concave reflecting surface, preferably by paraboloid-shape and spherical surfaces, and having a light-emitting element in, or near, the focus of the main reflecting surface and mounted on the current conducting support, and the envelope being shut-up by a transparent cover plate. The essence of the invention consists of having a convex mirror located between the light-emitting element and the cover plate, with its reflecting surface facing the light-emitting element and the concave reflecting surfaces. The surface of the convex mirror is preferably of the shape of a hyperboloid of rotation.

Abstract: The invention relates to a headlamp, the envelope of which is constituted internally by concave reflecting surfaces but at least by one concave reflecting surface having the shape of a paraboloid of rotation, further, in the focus of said paraboloid-shape reflecting surface a light-emitting element is accommodated with its center line being perpendicular to the axis of the reflecting surface, further, having said envelope shut up with a transparent cover plate, the surface of which is uniformly roughened, and/or on said surface uniformly distributed, geometrically regular beam-forming optical elememts are provided. Essential feature of the invention consists of having over the cover plate (1) also irregularly-shaped oblong beam-forming optical elements, the longitudinal axes of which are parallel with the center line (10) of the light-emitting element (2). Said oblong beam-forming optical elements are expediently cylindrical lenses (5, 6, 7, 8) or prisms.

Abstract: The invention relates to a current inlet conductor assembly particularly for vacuum devices, especially for light sources such as incandescent lamps or discharge tubes, comprising an inlet conductor made of molybdenum for passing electric current and being surrounded by a vitreous material forming a hermetic seal therewith and an intermediate metal coating covering the surface of the inlet conductor at least on the places to be welded. The essence of the invention is that the intermediate metal coating is made of rhenium, advantageously with a thickness from 3 to 1200 nm. As proposed, the intermediate rhenium layer should be produced by electrolytic deposition, especially from an aqueous solution.

Abstract: Electrical current supply terminal, especially for discharge tubes of light sources having a high pressure gas discharge.The invention is concerned with an electrical feed through, especially for discharge tubes of light sources having high pressure gas discharge, which current supply terminal is passed through a ceramic material, preferably from aluminum oxide and with a binding material is hermetically binded thereto, the heat expansion coefficient of which is appropriately selected and which is preferably vitreous enamel.In order to eliminate the difficulties resulting from the different heat expansion coefficient of ceramics, binding material and the metal material, the feed through is formed from a bundle of metallic threads.The bundle comprises preferably strands or braids and as material preferably molybdenum or tungsten is used.