Abstract: Ultraviolet (UV) radiation in the UV-C and UV-B bands, which is particularly dangerous, is absorbed and filtered by quartz glass doped with between 0.065% and 3.25%, and preferably between 0.065% and 1.3%, by weight, of cerium metal, or cerium as such. Preferably, the cerium is added to quartz sand and/or rock crystal, in form of a fine-grained powder of up to 20 .mu.m grain size, in form of cerium aluminate (CeAlO.sub.3), present in up to about 5% by weight, and preferably up to about 2%, by weight, and melted together in a single step. The quartz glass so obtained is particularly suitable for a metal halide discharge lamp, e.g. as an outer envelope (1), or as the discharge vessel (27) itself, or for halogen incandescent lamps, to form the quartz-glass light bulb or an envelope therefor. A small quantity of titanium oxide, up to about 0.05%, may be added as a further doping agent to the melt to further improve the UV absorption in the B and C bands.

Abstract: To permit high lamp currents to be applied to lamp electrodes (5, 6) of a discharge vessel (2) from which two elongated necks (3, 4) extend via current supply leads (23, 35), the discharge vessel is first made as a generally rotation-symmetrical element, to which tubular cylindrical neck tubes (17) are sealed. A cylindrical plug element (26, 40) is placed in the neck tube adjacent the discharge vessel. A subassembly is then made of a core element, which can be constructed as a single or a composite structure of quartz glass, for example by telescopically fitting quartz glass tubes over a central core, and melt-sealing the tubes and core together. Molybdenum disks (7, 8; 22) are placed against the end faces of the core element, and a plurality, for example four, molybdenum connecting foils (11-16, 27) are secured to the circumferences of the disks, to axially connect them together.

Abstract: To maintain a predetermined design color temperature throughout the lifet of a metal halide high-pressure discharge lamp, particularly suitable for illumination of theaters, film or television studios, the discharge vessel of the high-pressure lamp, typically made of quartz glass, contains a fill which, besides mercury, has a noble gas, cesium and dysprosium halide and a nickel halide. Optionally, gadolinium halide may be used. Per cubic centimeter of volume of the discharge vessel, 0.03 to 3 mg dysprosium, 0.002 to 0.5 mg nickel, and, optionally, 0.002 to 0.1 mg gadolinium are suitable. Suitable halogens for the halides are iodine and bromium, preferably in a mol relationship between 0.2 and 1.5. The metals, nickel and gadolinium limit the color temperature drop-off over the average lifetime of the lamp to at the most 1 K per operating hour of the lamp.

Abstract: To provide a high-pressure lamp capable of carrying lamp currents of 100 eres and higher, an essentially rotation-symmetrical discharge space (2) has two cylindrical necks (3, 4) melt-sealed thereto. Each one of the necks is formed of at least two telescoped hollow cylindrical quartz glass tubes (19, 27) which, with sealing foils circumferentially located within the neck, are all gas-tightly melt-sealed together. The sealing foils, typically of molybdenum, are electrically connected to a molybdenum disk (7, 8), for example by being welded to the circumference thereof which, in turn, is soldered to an end portion of an electrode shaft (5, 6), typically of tungsten, which extends into the discharge space of the discharge vessel.

Abstract: To increase the power output of a high-pressure metal halide discharge lamp aving a fill of mercury and at least one noble gas, and rare-earth halides which include at least one of: holmium; dysprosium, preferably present, each, of from 0.01 to 2.4 mg/cm.sup.3 of the discharge vessel, a gadolinium halide, present of from 0.01 to 2.3 mg/cm.sup.3 of the discharge vessel is additionally included in the fill. The discharge vessel is made of quartz, the electrodes of tungsten, and, in an example, a lamp operating at 12 kW, with 380 V power supply at 65 A is obtainable, the light output being comparable to that of daylight based on CIE standard D 60, with a color temperature of 6000.degree. K. so that an overall color temperature of about 5600.degree. K. is obtainable when the lamp is installed in a customary fixture, for example used in theatrical, film or television illumination application.