Abstract: A short-arc high pressure discharge lamp with a shorter distance between electrodes than a conventional lamp that realizes a long life of at least 3000 hours and suppresses the arc jump phenomenon is disclosed. In the high pressure discharge lamp, an electrode tip 124 is transformed into a semi-sphere by fusing and processing an electrode rod 122 and a coil 123 wound around an end of the electrode rod 122. A thickness “de” and a diameter “&phgr;e” of the semi-sphere are each set in a range predetermined in correspondence with a power input (W) of the short-arc high pressure discharge lamp.

Abstract: A mercury lamp of the short arc type which can stably emit an intense spectrum at a wavelength of 365 nm with an extremely narrowed band region over a long time, and which has an anode and a cathode disposed opposite one another in a silica glass arc tube which is filled with mercury and a rare gas, is achieved by the amount of mercury being less than or equal to 1.0 mg/cc of the inside volume of the arc tube and at least one of the gases argon (Ar) and krypton (Kr) are used as the rare gas at room temperature with 1.0 to 8.0 atm.

Abstract: A lamp unit (3) for use with digital micromirror devices has a direct current short arc discharge lamp (1) in which at least 0.15 mg/mm3 of mercury is sealed.

Abstract: A high pressure discharge lamp includes a quartz glass bulb having a sealing portion; and a pair of electrodes. Each electrode of the pair of electrodes is disposed so as to be opposite the other in the quartz glass bulb. The quartz glass bulb of the high pressure discharge lamp contains at least mercury and a halogen gas. The partial pressure of oxygen (O) in the quartz glass bulb is about 2.5×10−3 Pa or less and the partial pressure of the halogen gas in the quartz glass bulb is in the range between about 1×10−8 &mgr;mol/mm3 and 1×10−7 &mgr;mol/mm3.

Abstract: In a lighting system for motor vehicles, light from a HID or MPXL lamp is collected by a collector which surrounds the light source at least partly and is guided further to a separator of optical waveguide material, which separator forms a desired light beam via a specially shaped light outlet surface so as to obtain as high as possible a light output.

Abstract: A high-pressure gas discharge lamp (HID or UHP lamp, or in general lamps with mercury fillings of between approximately 0.05 and 0.5 mg/mm3) is described with at least one electrode (7, 8) which is provided with a thickened, for example globular portion (9, 10) at its end lying inside a lamp vessel (2). This portion is so dimensioned in dependence on operational parameters of the lamp and/or the diameter of the electrode rod that an electrode tip (19) forms itself independently at said portion during the first hours of operation. This tip grows from the portion until its free end starts melting. The electrode tip is self-adjusting in this manner, so that an optimum electrode interspacing is maintained throughout lamp life. Furthermore, a method of manufacturing such a lamp is described.

Abstract: The invention relates to a tubular discharge lamp (1) with a wall (4) which is transparent to UV-radiation. The tube (2) encloses a discharge space (5) having an internal diameter D. The discharge space (5) comprises a filling of mercury metal vapor in a concentration range of 0.4-2.5 mg/cm3. A reduction of both the diameter D from about 22 mm down to about 13.5 mm and the average mercury concentration from about 1.7 mg/cm3 down to about 0.8 mg/cm3 leads to an increase in the effective germicidal UV-output of the lamp (1) of about 35%.

Abstract: In a low-pressure mercury vapor discharge lamp which has an effective light emission length not shorter than 40 cm and a lamp input density not lower than 0.9 W/cm and which contains at least mercury as a light-emitting metal and an activating rare gas, the mercury is provided in an amalgam with another metal, and a thin coating functioning to trap a very minute amount of the mercury is formed on a glass inner surface of the discharge lamp. The thin coating contains, as its main ingredient, an oxide of at least one metal selected from a group of aluminum, silicon, calcium, magnesium, yttrium, zirconium and hafnium. The amalgam is secured to one or more locations of the glass inner surface facing a discharge space of the discharge lamp. Thus, it is possible to lower a necessary discharge-starting voltage and accelerate a rise time of a light amount of ultraviolet rays.

Abstract: A high pressure discharge lamp includes a luminous bulb in which a pair of electrodes are opposed to each other in the bulb. At least mercury and halogen are contained in the luminous bulb, and at least one metal selected from the group consisting of Pt, Ir, Rh, Ru and Re is present in the luminous bulb.

Abstract: A super-high pressure discharge lamp of the short arc type which has an arc tube portion in which there is a pair of opposed electrodes and which is filled with at least 0.15 mg/mm3 mercury, and side tube portions which extend from opposite sides of the arc tube portion and in which there are metal foils. The electrodes are each electrically connected to a respective one of the metal foils by a metallic component with cross-sectional area that is smaller than the cross sectional area of the electrodes in the area in which the electrodes are located in the side tube portions.

Abstract: A short arc mercury discharge lamp including an arc tube filled with at least mercury and a rare gas, a cathode and an anode positioned opposite to each other within the arc tube, the cathode having an tapered area which tapers in a direction towards the anode and a projection which protrudes from the tapered area in a direction towards the anode. The amount of mercury to be added in the arc tube is in a range of 0.2≦n≦52, where n is the weight (mg/cm3) of the mercury per unit of volume, and a pressure of the rare gas to be added in the arc tube is in a range of 0.1≦p≦800, where p is the pressure (kPa) of the rare gas at an ambient temperature of 25° C.

Abstract: The invention relates to a gas discharge lamp, in particular a high-pressure discharge lamp for use in automobiles. The invention further relates to a lighting system with at least one light source, at least one light coupling system, at least one optical waveguide, and at least one light delivery system. Such lighting systems with a central light source and a distribution of the light over optical waveguides (i.e. suitable optical fiber systems) in remote locations are particularly suitable for applications in the automobile branch. For this application, a high brightness must be available already after a short run-up time of the lamp. To provide a gas discharge lamp with a high brightness, which makes available a sufficient brightness after a short period, a gas discharge lamp is proposed with a bulb which has an ellipsoidal discharge chamber in a central location, which chamber has a surface area with a maximum value of below 2.5 cm.sup.

Abstract: A thallium-free high pressure ceramic metal halide lamp having superior dimming characteristics with a fill composition comprising MgI2 and CeI3. In addition, the fill chemistry comprises NaI and the halides of rare earth metals such as Dy, Ho and Tm.

Abstract: A hot-melt web has a buffer adhesive layer of a thermosetting resin on a light transmissive, heat resistant resin support. The hot-melt web has the advantages of light transparency, heat resistance, weather resistance, controlled entrainment of bubbles and easy removal of bubbles during thermocompression bonding, provides a sufficient bonding force, and effectively corrects random deformations of a module sheet. The hot-melt web is suitable for use in the bonding, joining and laminating steps in the manufacture of optical discs such as DVD and flat panel displays, is easy to eliminate bubbles, and is effective for improving the quality of an associated product. A laminate using the hot-melt web and a method for preparing the laminate are also provided.

Abstract: A method and apparatus for preventing the formation of leachable mercury in mercury arc vapor discharge lamps is provided which comprises providing in the lamp structure an effective amount of a silver salt, gold salt, or combination thereof.

Abstract: The invention relates to a high-pressure discharge lamp of the ceramic metal halide type of the Philips MasterColor® series having power ranges of about 150W to about 1000W. Such lamps are provided with a discharge vessel which encloses a discharge space. The discharge vessel has a ceramic wall and is closed by a ceramic plug. An electrode which is located inside the discharge space is connected to an electric conductor by way of a leadthrough element. The leadthrough element projects through the ceramic plug with a close fit and is connected thereto in a gas-tight manner by way of a sealing ceramic. The leadthrough element has a first part which is formed by a cermet at the area of the gas-tight connection.

Abstract: An electrodeless lamp includes a stationary bulb (10) containing a fill for producing a discharge, the fill has a primary radiating material which ordinarily produces an unstable discharge in the absence of bulb rotation. The fill further includes an alkali metal in an amount sufficient to stabilize the discharge without bulb rotation. The alkali metal may be, for example, cesium bromide. Preferably, the fill is excited by a non-stationary electric field (E, E1) such as, for example, a circular polarized electric field.

Abstract: A metal halide lamp with high color rendering index, greater then 80, with substantially constant color temperature through life. The lamp arc discharge vessel has a small volume, i.e., less than 1 cc, and contains iodides of sodium, scandium, lithium, dysprosium, and thallium along with mercury, a buffer gas and scandium metal. The addition of the scandium metal does not raise the arc discharge vessel temperature and significantly reduces the color temperature decline during life.

Abstract: A super-high pressure mercury lamp with an internal pressure during operation of one hundred and some dozen atm, which has a new arrangement in which in the hermetically sealed portions neither damage the lamp nor shortening its operating service life is achieved, in a high pressure mercury lamp in which a silica glass discharge vessel contains a pair of spaced apart, opposed electrodes and which is filled with a rare gas and with mercury in an amount of greater than or equal to 0.16 mg/mm3, and in which the wall load is greater than or equal to 0.

Abstract: A high pressure mercury lamp comprises a quartz envelope that contains an atmosphere and a pair of arc-discharge electrodes. These are coil-wound tungsten that has been doped to grain-stabilize the tungsten crystalline structure, e.g., with potassium or potassium and alumina. Preferred potassium doping levels of the tungsten material are in the range of 35-75 ppm. A suitable commercial product of alumina and potassium doped tungsten material is Type BSD-Sylvania. The atmosphere generally comprises a rare gas like xenon, to which is added no more than 0.2 mg/mm3 of mercury so as to keep operating pressure under 200 bar (197 atm). But the electrical power applied is sufficient to maintain arc power loadings of at least 150 watts/mm. The resultant wall loading is more than 0.8 watts/mm2, and lamp operating-power levels can be greater than 150 watts.

Abstract: A metal halide lamp for general illumination purposes contains as the essential component of the metal halide fill manganese in an amount of from 0.01 to 50 &mgr;mol per cm3. It serves as a replacement for sodium at warm white or neutral white luminous colors.

Abstract: Metal halide lamp for color applications for high wall loading with a long service life of at least 1500 hours and with a color temperature of over 5000 K: fill comprising at least the following constituents: firing gas, mercury, halogen, as well as indium, thallium, tin, no rare earth element or Na; the fill furthermore contains, as lithium replacement, hafnium, zirconium and tantalum, individually or in combination, the wall loading of the discharge vessel being at least 50 W/cm2; specific output based on die arc length is 50 to 90 W/mm; in particular, the concentration of the metals is as follows: lithium replacements: 0.20-4.0 &mgr;mol/ml; indium 0.3-3.0 &mgr;mol/ml.

Abstract: To devise a mercury lamp of the short arc type with high radiant efficiency and increased arc stability which meets the demand for increasing the amount of radiation from the light source. In a mercury lamp of the short arc type, a cathode and an anode are disposed opposite one another within an arc tube filled with mercury and a rare gas. At least argon (Ar) and/or krypton (Kr) in an amount from 1.0 to 8.0 atm at room temperature is added as the rare gas. In addition, the relationship between various dimensions of the lamp is fixed such that conditions 0.3≦X/L≦0.6, (X+5)/D≦0.85, and (L−(X+5))/D≦0.85 are satisfied, L (mm) being the length of the bulb in the axial direction, X (mm) being the length of the cathode which projects in the axial direction into the emission space, and D (mm) being the maximum outside diameter of the bulb in the radial direction.

Abstract: An electrodeless discharge lamp and an electrodeless discharge lamp apparatus which prevent the devitrification are provided, where the devitrification occurs due to the use of, as a luminescent substance, a metal halide, particularly a compound made up of a group IIIB metal and a halogen. The inventors recognize the cause of the devitrification as follows: atoms of the metal are dissociated from the luminescent substance and precipitate on the surface of the arc tube wall to melt it as the luminescent substance is excited and emits light. Based on this recognition, a substance is added to the interior of the arc tube to prevent the melting of the arc tube wall and extend the life of the lamp. More specifically, the added substance is another metal halide which contains a halogen, but the valence of the metal of the added metal halide is larger than that of the luminescent-substance metal halide.

Abstract: A low-pressure mercury-vapor discharge lamp is provided with a discharge vessel (10). The discharge vessel (10) encloses a discharge space (11) provided with a filling of mercury and an inert gas in a gastight manner. The discharge vessel (10) is provided with an amalgam which communicates with the discharge space (11). The discharge lamp comprises means for maintaining an electric discharge in the discharge vessel (10). The discharge lamp is characterized in that the amalgam comprises a bismuth-lead amalgam having a lead content in the range from 35≦Pb≦60 at. %, a bismuth content in the range from 40≦Bi≦65 at. %, and a mercury content in the range from 0.05≦Hg≦1 at. %. Preferably, the amalgam additionally comprises gold with a gold content in the range from 0.1≦Au≦20 at. %. Preferably, the gold content is in the range from 8≦Au≦12 at. %.

Abstract: The invention relates to a low-pressure gas discharge lamp which includes at least one discharge vessel and at least two capacitive coupling-in structures and operates at an operating frequency f. In order to achieve a better efficiency in combination with a small structural volume, a high luminous flux, a low operating voltage, a low electromagnetic emission, a high resistance against switching transients and a long service life for the low-pressure gas discharge lamp, it is proposed to form each capacitive coupling-in structure from at least one dielectric having a thickness d and a dielectric constant &egr;, each dielectric being subject to the condition d/(f.&egr;)<10−8 cm.s. A substantially larger amount of light can thus be generated per lamp length (lumen/cm).

Abstract: A high pressure discharge lamp includes a quartz glass bulb having a sealing portion; and a pair of electrodes. Each electrode of the pair of electrodes is disposed so as to be opposite the other in the quartz glass bulb. The quartz glass bulb of the high pressure discharge lamp contains at least mercury and a halogen gas. The partial pressure of oxygen (O) in the quartz glass bulb is about 2.5×10−3 Pa or less and the partial pressure of the halogen gas in the quartz glass bulb is in the range between about 1×10−8 &mgr;mol/mm3 and 1×10−7 &mgr;mol/mm3.

Abstract: A high-pressure mercury vapor discharge lamp comprises an arc tube in which a pair of electrodes are provided and in which a rare gas as a starting gas, a material from which a free halogen is to be produced during a lighting operation, and mercury are enclosed. The arc tube satisfies X/L≧88, in which X(W) is a lighting operation power and L (mm) is a distance between the electrodes. The high-pressure mercury vapor discharge lamp satisfies the following expression: 1.2≦&phgr;/(X×10−2+3.2)≦1.6 in which &phgr; (mm) is the inner diameter of the arc tube. Therefore, the high-pressure mercury vapor discharge lamp has a high luminance, a good emission spectrum, and a long life.

Abstract: A metal halide discharge lamp having a bulb which contains a fill including an ignition gas, mercury, a halogen, lithium, indium, thallium and tin, and which is devoid of a rare earth element. Such fill serves to lengthen the service life of the lamp. The lamp is especially suitable for effect lighting.

Abstract: The present invention provides a high pressure discharge lamp which is provided with a discharge tube containing a pair of electrodes therein and being filled with mercury, an inert gas and a halogen gas, the amount of the mercury filled being 0.12 to 0.35 mg/mm3, the halogen gas being at least one gas selected from the group consisting of Cl, Br and I and being present in an amount of 10−7 to 10−2 &mgr;mol/mm3, and the electrodes being mainly composed of tungsten, and the tungsten as a material of the electrodes contains not more than 12 ppm of potassium oxide (K2O). In such a high pressure discharge lamp, blackening of the discharge tube due to the potassium oxide (K2O) contained in the tungsten, and decrease in illumination maintenance can be prevented, thus providing a high pressure discharge lamp with a long lifetime, a lighting optical apparatus using the high pressure discharge lamp as a light source, and an image display system using the lighting optical apparatus.

Abstract: A metal halide or mercury lamp including an arc tube comprised of a glass composition consisting essentially of at least 90 weight percent SiO.sub.2 and including between about 10 and 1000 parts per million of a trivalent element slected from the group consisting of Pr, Nd, Pm, Sm, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Ac, Th, Pa, U, Np, Pu, Am, Cm, Bk, Cf, Es, Fm, Md, No, Lr, Unq, Unp, Ga, and mixtures thereof such that the viscosity of the glass composition is greater than 10.sup.14.5 poise at 1100.degree. C.

Abstract: In a metal halide lamp which includes a discharge tube (2) retaining a fill of mercury and at least one metal halide added as a luminous material, an energy density of the arc discharge portion (3) represented by a product E.times.j is in the range of 70.0.ltoreq.E.times.j.ltoreq.150.0 (VA/mm.sup.3) where E=V/d, j=I/S, assuming that I is a lamp current in amperes with a lamp voltage of V volts applied between the paired discharge electrodes in a stable lighting condition of the lamp and that each of the electrodes has a tip face (1a, 1a') of which a cut area in section is S mm.sup.2 and the gap distance is d in millimeters, and thus a high luminous flux retention rate and high luminance of an arc discharge portion can be accomplished with a longer life of the lamp, suppressing a lamp voltage varying rate, and avoiding a change in color temperature, which remarkably improves additional merits when in utilization as a light source in various display apparatuses such as optical projection systems.

Abstract: A high pressure mercury lamp with an extremely high mercury vapor pressure and extremely high tube wall load in which the arc during operation is advantageously stabilized is achieved in a high pressure mercury lamp having a discharge vessel of fused silica glass which contains a pair of opposed tungsten electrodes, mercury in an amount at least equal to 0.16 mg/mm.sup.3 and a rare gas, and in which the discharge tube has a tube wall load at least equal to 0.8 W/mm.sup.2, by at least one metal halide with a metal having an ionization potential that is at most 0.87 times as high as the mercury ionization potential being added to the discharge tube in a range of from 2.times.10.sup.-4 to 7.times.10.sup.-2 .mu.mole/mm.sup.3.

Abstract: The high-pressure sodium discharge lamp of low power described here is chcterized by a very high xenon cold filling pressure of at least 1 bar. The pressure ratio to the sodium operating pressures lies between 10 and 30. Luminous efficacies of approximately 100 lm/W and more can be obtained with a lamp power of 50 to 100 W.

Abstract: The formation of leachable mercury upon disposal or during TCLP testing of mercury vapor discharge lamps is substantially prevented by maintaining the amount of elemental iron at a level of less than about 1.1 milligrams per kilogram of total lamp material.

Abstract: A high performance miniature projection lamp which includes a glass envelope having a pair of opposite neck portions each with a coaxial central opening having a reduced section and an hermetically sealed central chamber having a volume of about 130 mm.sup.3 which contains a fill. The fill includes an argon pressure at room temperature at a range of about 0.5 atmospheres to about 2.0 atmospheres and mercury in an amount in the range of about 5 mg to about 15 mg, and a mixture of metal halide material in an amount from about 50 up to 1000 micrograms. A pair of axially aligned electrodes are positioned at opposite neck portions and separated form each other by a predetermined distance. The electrodes each have a shank portion which each having a coil wrapped around its end.

Abstract: A ceramic discharge vessel for a high-pressure discharge lamp is formed of a cylindrical central part and two hemispherical end pieces, whereby the length of the central part is smaller than or equal to the radius of the end pieces. In this way, the isothermy of the discharge vessel is improved.

Abstract: A metal-halide high-pressure discharge lamp (1) with a discharge vessel (2) nd two electrodes (4, 5) has inside discharge vessel (2) an ionizable filling, which contains yttrium (Y) in addition to inert gas, mercury, halogen, thallium (Tl), hafnium (Hf), whereby hafnium can be replaced wholly or partially by zirconium (Zr), dysprosium (Dy) and/or gadolinium (Gd) as well as, optionally, cesium (Cs). Preferably, the previously conventional quantity of the rare-earth metal is partially replaced by a molar equivalent quantity of yttrium. With this filling system, a relatively small tendency toward devitrification is obtained even with high specific arc powers of more than 120 W per mm of arc length or with high wall loads. Thus, the filling quantity of cesium can be clearly reduced relative to a comparable filling without yttrium, whereby an increase in the light flux and particularly in the brightness can be achieved.

Abstract: A lamp for providing visible radiation includes tellurium or a tellurium compound in the fill. This substance is present in an amount such that when the fill is excited with sufficient power, substantially all of the radiation resulting from tellurium is emitted at wavelengths exceeding 400 nm. When tellurium is added to a sulfur or selenium based lamp for emitting visible radition, the spectrum is shifted towards the red region.

Abstract: A mercury lamp of the short arc type with high radiant efficiency which satisfies the demand for an increase of the radiation amount of the light source, by suppressing the motion of the bright spot in the vicinity of the cathode tip suppresses the flickering of the irradiance and thus increases the arc stability, is achieved in a mercury lamp of the short arc type in which within an arc tube mercury and at least one rare gas are encapsulated, by either at least Ar being filled as the rare gas at an filling pressure of from 1 to 8 atm, and by the current density in the tip area of the cathode being 10 to 250 A/mm.sup.2 or alternatively, at least Kr being filled as the rare gas at an filling pressure of from 1 to 8 atm, and the current density in the tip area of the cathode being 10 to 310 A/mm.sup.2 during operation of the lamp.

Abstract: An electrodeless metal vapor discharge lamp having an airtight arc tube formed with a light transmitting material of metal oxide and containing as sealed therein luminescent substances containing at least one or more of rare earth metallic halide, further includes a promoting substance which renders a halogen cycle occurring adjacent to inner wall surface of the arc tube to be more easily promoted, so as to prevent lamp starting voltage from raising up.

Abstract: The spectral energy characteristic of a discharge lamp is controlled by changing the density of the fill substance. The spectral characteristic can be shifted while substantially maintaining its shape by changing the density of the fill. A sulfur or selenium containing discharge lamp which is operated at a pressure of at least about 1 atmosphere contains a low ionization potential substance in the fill. Characteristics which are improved are one or more of spatial color uniformity, extinguishing characteristics, and bulb starting reliability. Particular substances which are added to the fill are alkali metal containing substances, III B metal containing substances, and alkaline earth metal containing substances. When light is reflected back into the bulb, the light which is re-emitted is stronger in the higher wavelengths.

Abstract: The apparatus has a light transmitting bulb for confining a discharge therein, a fill sealed within the light transmitting bulb and including a rare gas and a metal halide emitting a continuous spectrum by molecular radiation, and a discharge excitation source for applying electrical energy to the fill and for starting and sustaining an arc discharge, and the metal halide includes one kind of halide selected from the group consisting of an indium halide, a gallium halide, and a thallium halide, or a mixture thereof, and in that the light transmitting bulb has no electrodes exposed in discharge space and further this construction utilizes the continuous spectrum of molecular radiation of the metal halide and thereby achieves high color rendering properties and high luminous efficacy simultaneously without using mercury as the fill.

Abstract: A projection lamp includes a metal halide discharge lamp (1) with a lightansparent discharge vessel (2) in which two electrodes (3) stand opposite one another, which are joined with current leads (5) led to the outside, whereby the discharge vessel contains an ionizable filling including mercury, at least one noble gas, at least one halogen, one rare-earth metal (RE) as well as another metal, niobium, for the formation of metal halides. The addition of metallic niobium provides the lamp with good color reproduction and good arc stability.

Abstract: A lamp in which a stable, long-term luminous operation can be accomplished is achieved by the fact that, in a mercury lamp of the short arc type in which a cathode and an anode located next to one another within an arc tube and in which both ends of the arc tube are provided with hermetically sealed portions, the cathode is installed on the tip of a rod-shaped component which extends from a respective one of the hermetically sealed portions, the cathode having a greater outer diameter than the rod-shaped component on which it is installed, and the rear end of the cathode tapering toward the respective hermetically sealed portion.

Abstract: A sodium containing lamp constructed to include of a fused quartz or fused silica arc chamber wherein the fused quartz and/or fused silica contains less than about 0.05 parts per million sodium. The arc chamber of the invention demonstrates a resistance to sodium diffusion resulting in a longer lived lamp with excellent color maintenance.

Abstract: The invention relates to a high-pressure discharge lamp with an outer bulb urrounding the discharge vessel, and to a process for producing a high-pressure discharge lamp. The outer bulb (1) comprises a glass that has a low viscosity and in particular a lower softening temperature than the quartz glass of the discharge vessel (2), and is melted directly onto the ends (5a, 5b) of the discharge vessel (2), which is sealed on both ends. As the glass for the outer bulb, a quartz glass doped with viscosity-lowering additives, in particular alkaline-earth metal borates, is used, while the discharge vessel comprises undoped quartz glass. In addition, the quartz glass of the outer bulb is preferably doped with rare earth metal additives that absorb UV radiation.

Abstract: An arc tube for a high intensity discharge lamp. The arc tube has a hermetically sealed body formed from a vitreous material subject to devitrification, at least two oppositely disposed electrodes are sealed in the body. An are generating and sustaining medium is provided in the body and operates to produce visible light when an electric current is applied to the electrodes. The are tube has a given color rendering index, and at least a portion of the medium comprises a color correcting component of lithium iodide which contributes no only to the given color rendering index but which also acts as a devitrification agent. The improvement comprises an anti-devitrification component in the medium, the anti-devitrification component having a minimal detrimental effect on the given color rendering index while increasing the life of the are tube.

Abstract: A highly efficient discharge lamp has a color rendering index of about 85, a lumens per watt rating of about than 90, a correlated color temperature of 3000.degree. K., and a wall loading of about 21 W/cm.sup.2. The lamp has an outer glass envelope and a pair of electrical conductors extending into the interior of the glass envelope; a quartz discharge tube disposed within the outer envelope and including a pair of spaced electrodes which are electrically connected to the electrical conductors for creating an electrical discharge during operation of the lamp, the discharge tube having an arc chamber. An arc generating and sustaining medium is provided within the arc chamber and includes the halides of sodium, scandium, lithium, dysprosium and thallium, a fill gas selected from argon and xenon, and a given quantity of mercury to achieve a desired lamp voltage. In a preferred embodiment of the invention the halides are iodides and are present in the mole ratio of about 24-44:1:9.

Abstract: A metal-halide discharge lamp for photooptical purposes has a small electe spacing of less than 15 mm, preferably 2-8 mm, to provide an essentially pin-point light source, and a fill which contains AlI.sub.3 in an amount between 0.1 and 4.5 mg/cm.sup.3. Other filling components may in particular be halides of mercury, indium, thallium or cesium; up to 2 mg/cm.sup.3 of AlBr may be added. The lamp is particularly adapted for combination with a, preferably parabolic, reflector.