Abstract: An emitter is disclosed. The emitter includes a base layer, where the base layer includes an emissive region of nanocavities and wherein the base layer includes hafnium and nitrogen. A radiation source including the emitter is also disclosed.

Abstract: [Problem] To provide a light-emitting device as a point light source having a broad emission spectrum by a safe and simple process. [Means for Solving the Problem] The discharge light source shown in FIG. 1 is composed of an insulated pipe 30 and electrodes 31a and 31b. Projections 32a and 32b extend from the electrodes 31a and 31b. When a voltage is applied to the electrodes 31a and 31b in an argon gas flow through the insulated pipe 30 passing between the projections 32a and 32b, a glow discharge is generated thereby emitting light in the area between the projections 32a and 32b. The interval between the projections 32a and 32b is so narrow that the emitting area is small, and thus the light source serves as a point light source. The emission intensity increases with an increase of the gas flow rate, whereby a continuous broad emission spectrum is produced over the ultraviolet to visible region.

Abstract: A dielectric barrier discharge lamp 100 has an internal electrode 11 inside a bulb 10, and an external electrode 12 outside the bulb 10. Lamp capacity C0 per inner surface area of the bulb between the internal electrode and external electrode is set to less than 2.8 nF/m2. By setting lamp capacity C0 within this range, lamp efficiency ?, which is a value obtained by dividing an output luminous flux of the lamp by an power inputted to the lamp, is remarkably increased.

Abstract: A ceramic metal halide lamp wherein the halide dose includes the following component ranges in mol/cm3: Nal: 1.84×10-5 to 2.33×10-5, Lnl3: 5.20×10-6 to 6.60×10-6, Tl: 1.76×10-7 to 2.23×10-7, wherein Ln are lanthanide elements, and further includes a halide dosage weight of between 0.40 to 0.77.

Abstract: A fluorescent lamp includes a light-transmissive envelope, means for providing a discharge, a gas fill comprising mercury vapor and an inert gas sealed inside the envelope, a barrier layer on the inner surface of the envelope and a phosphor layer on the barrier layer. The phosphor layer contains at least one phosphor and alpha alumina and has a coating weight from about 1 to about 5 mg/cm2.

Abstract: The arc tube is provided with a mercury-free arc tube main body that has a discharge light-emitting portion (closed glass sphere), and a cylindrical shroud glass tube that is airtightly integrated with the arc tube main body. In the mercury-free arc tube in which an inert gas is sealed in the shroud glass tube that surrounds the closed glass sphere, in the shroud glass tube, the adjustment is made so as to satisfy the light flux and the life span with respect to the pressure X (atmospheric pressure) of a rare gas sealed in the closed glass sphere, and an amount M (mg/ml) of sealed metal halide.

Abstract: Process for producing a discharge lamp having a silica discharge vessel with an emission space in which there is a pair of electrodes at least 0.15 mg/mm3 of mercury, argon (Ar), and halogen by measuring the relation b/a1 between the emission intensity a1 of argon (Ar) at a wavelength of 668 nm and the emission intensity b of OH radicals at a wavelength of 309 nm in a state of glow discharge of the discharge lamp; supplying hydrogen into the discharge vessel of the discharge lamp; measuring the relation c/a2 between the emission intensity a2 of argon (Ar) at a wavelength of 668 nm and the emission intensity c of OH radicals at a wavelength of 309 nm in the state of glow discharge of the discharge lamp; and fixing the difference c/a2?b/a1 at a value in the range of 0.001 to 15.

Abstract: A metal halide lamp of the present invention has an arc tube formed of ceramic and a pair of opposing electrodes. This lamp includes a Pr (praseodymium) halide, a Na (sodium) halide, and a Ca (calcium) halide enclosed within the arc tube. The Pr halide content Hp [mol], the Na halide content Hn [mol], and the Ca halide content Hc [mol] satisfy the relationships of 0.4?Hc/Hp?15.0 and 3.0?Hn/Hp?25.0.

Abstract: There are provided a mercury-free metal halide lamp which suppresses occurrence of flickering of light emission, and is improved in light flux rising immediately after starting, and more practical and suitable for a headlight, and a metal halide lamp lighting device and a headlight using this. A metal halide lamp according to the present invention comprises: a translucent air-tight container having an inner volume which is not greater than 0.1 cc; a pair of electrodes sealed facing each other with an inter-electrode distance which is not greater than 5 mm in the translucent air-tight container; and a discharging medium containing a plurality of metal halogen compounds selected from a group of scandium (Sc), sodium (Na), indium (In), zinc (Zn) and a rare-earth metal and a rare gas but intrinsically not containing mercury (Hg), wherein a tube wall load is not smaller than 60 W/cm2, and a ratio Vo/Vl satisfies an expression 0.45?Vo/Vl?0.72, where Vo is an average lamp voltage for 0.

Abstract: A Sr(Al,Mg)12O19:Ce,Pr phosphor is described wherein the phosphor has an increased sensitivity to excitation by 185 nm radiation compared to a Sr(Al,Mg)12O19:Ce phosphor. The Ce,Pr-coativated strontium magnesium aluminate phosphor emits ultraviolet (UV) radiation at about 306 nm in the UVB region. Suntan lamps made with this phosphor exhibit improved performance over lamps made with a commercial Sr(Al,Mg)12O19:Ce phosphor.

Abstract: A device for generating ultraviolet radiation by means of an excimer discharge, which device is equipped with an at least partly UV-transparent discharge vessel whose discharge space is filled with a gas filling, with means for triggering and maintaining an excimer discharge in the discharge space, and with a luminescent material that contains a phosphor comprising a host lattice of general formula (Y1-x-y-z,Lux,Scy,Az)PO4 wherein 0?x<1 and 0<y?1 and 0?z<0.05 and A is an activator selected from the group of bismuth, praseodymium and neodymium is useful for disinfection and purification of fluids and surfaces and provides improved germicidal action. The invention also relates to a UVC-phosphor comprising a host lattice of general formula (Y1-x-y-z,Lux,Scy,Az)PO4 wherein 0?x<1 and 0<y?1 and 0?z<0.05 and A is an activator selected from the group of bismuth, praseodymium and neodymium comprising a improved emission spectrum.

Abstract: The UVC emission of a Sr(Al,Mg)12O19:Pr is improved by providing an excess of magnesium relative to the molar amount praseodymium In particular, the UVC-emitting phosphor has a composition represented by the formula Sr1-xPrxAl12-yMgyO19 wherein y>x. The phosphor is excited by vacuum ultraviolet radiation and may be used to create a mercury-free germicidal lamp.

Abstract: A UV-emitting phosphor is described wherein the phosphor is excitable by vacuum ultraviolet radiation (VUV). The phosphor is a gadolinium-activated strontium magnesium aluminate which preferably has an excitation maximum at about 172 nm. The phosphor exhibits a narrow-band UV emission at about 310 nm which makes it useful for medical phototherapy applications.

Abstract: A plasma lamp is provided having an integrated dielectric waveguide structure having a body, a gas housing formed within the body and having an aperture formed at a first outer surface of the body, a fill mixture disposed within the gas housing, and a probe operatively coupled to the body so that microwave energy supplied to the fill mixture forms a plasma that emits high intensity light.

Abstract: The invention relates to an incandescent halogen lamp, comprising at least one tungsten incandescent filament (3) in a transparent light bulb (1) and a filling in the light bulb (1), which has a halogen component for a halogen recycling process and a noble gas component containing krypton or xenon, whereby the noble gas component comprises at least one further noble gas, the atoms of which have a smaller atomic radius than krypton atoms and the cold filling pressure within the light bulb (1) is greater than or equal to 0.7 Megapascal. Said incandescent halogen lamp is suitable as light source in a curved lamp or as combined day running or position light in a motor vehicle.

Abstract: A UV-emitting phosphor and lamp containing same are described. The phosphor is a praseodymium-activated pyrophosphate-based phosphor which may be represented by the general formula (Ca2-x,Srx)P2O7:Pr where 0?x?2. The phosphor is excitable by vacuum ultraviolet (VUV) radiation and in particular it may be excited by Xe-excimer discharges and thereby provide a Hg-free UV-emitting lamp. The phosphor exhibits a broad emission in the UVC region in the wavelength range from about 220 nm to about 280 nm with the peak emission occurring in the wavelength range from about 230 nm to about 240 nm. The emission characteristics of the phosphor may be varied depending on the ratio of Sr/Ca.

Abstract: The invention relates to a high-pressure discharge lamp that has an electric power consumption of less than 50 watt and comprises a discharge vessel (1?) that is sealed on two sides and is made of a translucent ceramic material as well as electrodes (2?, 3?) which are disposed inside the discharge vessel (1?) and are used for generating a gas discharge. Xenon and metal halides are arranged within the discharge vessel (1?) which is embodied as a ceramic tube that has a uniform maximum inner diameter of 1.2 mm while the minimum cold filling pressure of the xenon amounts to 0.8 megapascal.

Abstract: A metal vapor discharge lamp whose near-infrared radiation is stronger than a conventional high-pressure discharge lamp, a projector utilizing this discharge lamp, and a metal vapor discharge lamp lighting device are disclosed. The metal vapor discharge lamp comprises a refractory light-transmitting hermetic vessel, a pair of electrode fixed to the hermetic vessel, and a discharge medium sealed in the hermetic vessel and containing a halide and a rare gas. Most of the light irradiated when the discharge lamp is in the ON state has near-infrared wavelengths (750–1100 nm).

Abstract: There is provided a surface light source device containing 50 ppm or less of water, 50 ppm or less of nitrogen, 30 ppm or less of oxygen, 20 ppm or less of carbon monoxide, and 20 ppm or less of carbon dioxide as impurities in its discharge space. Accordingly, the surface light source device with the impurity standards has improved brightness.

Abstract: A radiation source with an ionizable mercury-free composition. The ionizable composition including at least zinc or at least one zinc compound or both.

Abstract: Metal halide lighting with good color during dimming may be obtained. An appropriate balance of commonly used metal halides (NaI, DyI3, CeI3, CaI2, TlI) is dosed in the lamp. No mercury is used. A higher than typical xenon fill pressure from 50 to 500 Kilopascals may be used to help control thermal properties and voltage. If necessary, modulation of the power at acoustic resonance frequencies may be used to straighten and center the arc. Efficient and pleasant white output is obtained. As the power is reduced, the chromaticity either (1) remains fairly constant or (2) drifts acceptably towards warm pinkish colors. Large factors of attenuation in output can be realized. The lumen output was reduced by at least a factor of twenty in one sample as the power was dimmed from 70 to 20 watts.

Abstract: In a flat display device having a pair of substrates for defining a gas discharge space in which a gas used to generate discharge luminance is sealed, means for absorbing or reflecting near infrared rays is included.

Abstract: A lighting system includes a fluorescent lamp 4 and a main body 1 for attaching the fluorescent lamp 4 thereto. The main body 1 is provided with a socket assembly 6 for the attachment of the fluorescent lamp 4, and an electronic ballast 7 for operating the fluorescent lamp 4 at dimmed levels (as well as at the full light level). The fluorescent lamp 4 is composed of a discharge tube formed of four U-shaped glass tubes that are connected together to form a square in plan view. Each glass tube has an inner diameter of 13.5 mm, and the discharge tube is filled with a rare gas containing neon and argon (at 50:50 ratio by volume).

Abstract: A metal halide lamp includes a fire-resistant and translucent hermetic vessel containing amounts of scandium halide and sodium halide sealed in the hermetic vessel satisfying the formula of 0.25<a/(a+b)<0.5, where reference character “a” denotes the mass of scandium halide and reference character “b” denotes the mass of sodium halide.

Abstract: A metal halide lamp in which an arc tube is housed within a bulb having a base at one end thereof. The arc tube includes a main tube, two thin tubes that extend one from each end of the main tube, and a pair of electrode inductors. The main tube and the thin tubes are made from translucent polycrystalline alumina and constitute a discharge vessel having a discharge space therein. Lamp power under dimming conditions is set in a range defined by maximum lamp power Wmax [W] and minimum lamp power Wmin [W], with a surface area S [cm2] of the inner surface of the discharge vessel satisfying Wmax/60?S?Wmin/20.

Abstract: In a discharge tube of the present invention, a filler gas is composed of a mixture of inert gas and hydrogen gas and an airtight cylinder 10 in which the filler gas is enclosed in an airtight manner is provided. A pair of first and second discharge electrodes 22 and 24 are opposed to each other within an internal space of the airtight cylinder, so that an electric discharge is generated between discharging surfaces of the first and second discharge electrodes. In the discharge tube, a concentration of the hydrogen gas in the filler gas is set in a range from 20 percent by volume to 80 percent by volume.

Abstract: A metal halide lamp comprises a discharge container including a discharge space and a pair of sealing sections. A discharge medium containing a metal halide and a rare gas and essentially free from mercury is sealed in the discharge container. A pair of electrodes are arranged to face each other within the discharge space, and the side edge portions on the side of the proximal end portion of these electrodes are held by the sealing sections. The amount of water contained in the metal halide, i.e., the light-emitting material, included in the metal halide lamp essentially free from mercury, i.e., Hg-less metal halide lamp, is controlled to 50 ppm or less.

Abstract: In a flat display device having a pair of substrates for defining a gas discharge space in which a gas used to generate discharge luminance is sealed, means for absorbing or reflecting near infrared rays is included.

Abstract: A metal halide discharge lamp which essentially permits disusing mercury is provided. The metal halide discharge lamp comprises a refractory and transparent hermetic vessel, a pair of electrodes fixed to the hermetic vessel, and a discharge medium sealed in the hermetic vessel and containing a first halide, a second halide, and a rare gas. The first halide is a halide of a metal which achieves a desired light emission. The second halide has a relatively high vapor pressure, being at least one halide of metal which is unlikely to emit a visible light compared with the metal of the first halide and acts as a buffer gas.

Abstract: A light source device includes at least one discharge tube, a discharge medium sealed inside the discharge tube, and first and second electrodes for exciting the discharge medium. The first electrode is arranged inside or outside the discharge tube, and the second electrode has a plurality of contact portions at which the second electrode is in contact with an outer surface of the discharge tube. The contact portions are located at different distances from the first electrode and are provided discontinuously. Thus, it is possible to provide a light source device with an improved light emission efficiency, and a liquid crystal display device in which the light source device is employed.

Abstract: A metal halide fill for forming an ionizable fill comprising at least one inert gas, mercury, and at least one halogen, the fill additionally comprising the following constituents: Mn halide and V halide. This fill may in particular be present in the discharge vessel of a metal halide lamp.

Abstract: To provide a high-efficiency and long-life high intensity discharge lamp that is obtained by a configuration in which a neon gas or a neon-based gaseous mixture is filled as a starting-assistance rare gas for an alumina ceramic arc tube, and a filling pressure is set to 13 kPa or more. The high intensity discharge lamp is provided with the alumina ceramic arc tube having a discharge arc tube, alumina ceramic narrow tubes formed at both end portions of the discharge arc tube, electrodes and power feeders, the electrodes and the power feeders being arranged to form spaces in the narrow tubes. The discharge arc tube is filled with the neon gas or the neon-based gaseous mixture as the starting-assistance rare gas at a filling pressure of 13 kPa or more.

Abstract: A long-life high-pressure discharge lamp suffers reduced blackening and luminance drop even after it has been turned on over a long period of time, and is arranged to prevent the internal gases from leaking out and also to prevent the lamp bulb from being ruptured. The high-pressure discharge lamp has a pair of confronting electrodes inserted in a lamp bulb which confines therein at least mercury and a halogen gas. The lamp bulb contains oxygen at a partial pressure lower than a partial pressure which can maintain a luminance of 80% after 100 hours of operation and equal to or higher than 1.0×10?5 Pa.

Abstract: The invention relates to a high-pressure gas discharge lamp, particularly a motorcar lamp, comprising a bulb including at least two neck portions and a vacuum-tight discharge vessel of quartz glass, at least two electrodes projecting into the discharge vessel, and a filling in the discharge vessel which, in the operating state, is in a discharge state. Such lamps are used, in particular, in headlights of motorcars. In order to ensure that the arc of the high-pressure gas discharge lamp generates a higher luminescence in a small area, and the lamp can be used as a light source in motorcar headlights, the discharge vessel of the high-pressure gas discharge lamp in accordance with the invention encloses a discharge space having a width B below 4 mm and a length C below 8 mm, and the filling comprises NaI, ScI3, Xe, ZnI3 and is free of Hg. Surprisingly it has been found that the use ZnI2 in the filling causes the arc to generate a higher luminescence in the area of the arc axis per dimension of the arc.

Abstract: A compact fused silica, electroded HID lamp for automotive forward lighting, which contains no mercury. The lamps voltage, approximately 40 volts, is developed in this lamp by vaporizing zinc iodide instead of mercury. A compromise between voltage and luminous flux is achieved through the choice of the sodium scandium (Na:Sc) molar ratio, between 4.5:1 and 6:1 and a zinc iodide (ZnI2) dose of 2 to 6 micrograms per cubic millimeter that permits the lamp to operate within the North America, European and Japanese automotive color specifications for white light. The voltage in the lamp can be controlled according to the zinc iodide doping level without seriously impacting the visible spectrum otherwise provided by the other known dopants in the lamp.

Abstract: The high-pressure gas discharge lamp (1) comprises a lamp vessel (2) having a wall (3) which is exposed to a wall load of at least 30 W/cm2 during operation of the lamp, and a discharge space (4) in which a pair of electrodes (5) is disposed. The discharge space (4) has a filling which comprises mercury, argon, and halides (not fluorides) of tin and indium, to which filling an alkali metal halide is added, the alkali metal being potassium, rubidium, or cesium, and the halide being chlorine, bromine, or iodine. The high-pressure discharge lamp (1) according to the invention has an improved resistance against corrosion and crystallization of the quartz glass wall (3).

Abstract: Metal halide lamps have a discharge vessel operable at a high coldest spot temperature. The discharge vessel encloses a discharge space comprising an ionizable gas filling and, in addition to Hg, also an alkali iodide of Na of Li or a combination of both. According to the invention, the filling also comprises TbI3 or GdI3 or a combination thereof.

Abstract: An apparatus for providing a visual lightning effect includes a first chamber and a second chamber, where a passageway connects the first chamber and the second chamber. An inert gas is provided within the first chamber, the second chamber, and the passageway. A first contact is located external to the first chamber; and a second contact is located external to the second chamber, wherein an electrode provides a charge to the second contact, wherein the charge causes an electrical discharge between the second contact and the first contact via channels provided by fill material located within the second chamber that traverses the passageway to the first chamber, thereby resulting in the brilliant visual lightning effect.

Abstract: A light source device includes at least one discharge tube, a discharge medium sealed inside the discharge tube, and first and second electrodes for exciting the discharge medium. The first electrode is arranged inside or outside the discharge tube, and the second electrode has a plurality of contact portions at which the second electrode is in contact with an outer surface of the discharge tube. The contact portions are located at different distances from the first electrode and are provided discontinuously. Xenon gas and at least one selected from argon gas and krypton gas are sealed in the discharge tube, in which the xenon gas accounts for 60 vol % to 80 vol %. Thus, it is possible to provide a light source device and a liquid crystal display device that provide light emission with high brightness and excellent brightness distribution and that can be manufactured readily.

Abstract: The objective of the present invention is to provide a phosphor for use in a light emitting element excited by vacuum ultraviolet-ray that has high brightness even after plasma exposure. This object is achieved by a phosphor comprising a compound represented by a formula M11−aM211−bMna+bO18−(a+b)/2 (wherein, M1 represents at least one of materials selected from the group consisting of La, Y and Gd, and M2 represents at least one of materials selected from the group consisting of A1 and Ga, a represents a number in a range from not less than 0 to less than 1, b represents a number in a range from not less than 0 to less than 1, and sum of a and b is greater than 0), and by a light emitting element excited by vacuum ultraviolet-ray comprising the above-mentioned phosphor.

Abstract: A bulb for an electrodeless lamp comprises: an envelope through which the light can be permeated; a filled material filled in the envelope for emitting the light as being excited by high frequency energy; and buffer gas, wherein the buffer gas comprises first buffer gas, and second buffer gas having a partial pressure less than 1% of the partial pressure of the first buffer gas in order to reduce a discharging voltage and lighting time, and thereby, the re-lighting after putting out the light can be performed easily and the re-lighting time is reduced to improve the convenience of the user and the reliability of electrodeless lamp.

Abstract: A lighting system includes a fluorescent lamp 4 and a main body 1 for attaching the fluorescent lamp 4 thereto. The main body 1 is provided with a socket assembly 6 for the attachment of the fluorescent lamp 4, and an electronic ballast 7 for operating the fluorescent lamp 4 at dimmed levels (as well as at the full light level). The fluorescent lamp 4 is composed of a discharge tube formed of four U-shaped glass tubes that are connected together to form a square in plan view. Each glass tube has an inner diameter of 13.5 mm, and the discharge tube is filled with a rare gas containing neon and argon (at 50:50 ratio by volume). When operating the fluorescent lamp 4 at the full light level, the electronic ballast 7 applies the nominal lamp current of 0.43 A.

Abstract: A phosphor having a high emission luminance and a vacuum ultra-violet radiation excited light emitting element in which the phosphor is used are provided. The phosphor may be made of Ba, Gd, Y, B, O, and an activator (one or more selected from the group consisting of Ce, and Tb). The phosphor may be expressed by a composition formula of BaGd1-a-bYaLnbB9O16 where Ln represents at least one selected from the group consisting of Ce, and Tb, and a and b satisfy 0.05≦a≦1 and 0.003≦b≦0.5, respectively. The foregoing phosphors are suitably used in a vacuum ultra-violet radiation excited light emitting element. The vacuum ultra-violet radiation excited light emitting element may comprise any one of the foregoing phosphors.

Abstract: A metal halogen electrodeless illumination lamp including a microwave generator coupled via a coupling means with a microwave cavity which contains a discharge bulb, and a microwave screen its function being performed by some part of the microwave cavity walls, which is transparent to optical radiation The discharge bulb contains a fill mixture of metal halogens, such as Bi halide, a mixture of Sn and Al and a mixture of their compounds, which emits visible optical radiation featuring a molecular spectrum.

Abstract: A mercury-free metal halide arc lamp having an arc vessel of fused silica, an aspect ratio greater than 5, and containing a noble gas such as xenon, argon or krypton and a metal halide. In a preferred embodiment, the arc vessel has a diameter of 8 mm and a length of 80 mm, a fill of sodium/scandium iodides and a buffer gas of xenon.

Abstract: A low-pressure gas discharge lamp having a gas discharge vessel containing a gas filling with a chalcogenide of the elements of the 4th main group of the periodic systems of elements and a buffer gas, and having inner or outer electrodes and means for generating and maintaining a low-pressure gas discharge.

Abstract: The invention provides an arc tube with improved chromaticity and start-up characteristics that does not contain mercury, and provides a vehicle headlamp equipped with a metal halide lamp that contains no mercury in the arc tube. Among other improvements, the evaporation of low melting point metal halides is promoted and the start-up characteristics of the arc tube are improved.

Abstract: An alternating current driven type plasma display device includes a plurality of sustain electrodes having a spacing less than 5×10−5 m and a discharge gas in a discharge space where discharge takes place. The discharge gas consists of xenon gas alone having a pressure greater than or equal to 1.0×104 Pa and less than or equal to 3.0×104 Pa or the discharge gas consists of krypton gas alone having a pressure less than or equal to 6.6×104 Pa.

Abstract: It is desired to provide an aluminate phosphor having a high emission luminance, a method for producing the same, and a vacuum ultra-violet radiation excited light emitting element in which the aluminate phosphor is used. A method for producing an aluminate phosphor by mixing an &agr;-alumina powder, an aqueous solution containing a cation of a metal composing the aluminate phosphor, and a precipitant that precipitates the cation, and drying and calcining an obtained mixture of precipitates is provided. The foregoing method is further arranged so that the cation is a cation of at least one metal selected from the group consisting of Ba, Mg, Eu, Mn, Sr, Ca, Tb, Ce, and Zn is provided. An aluminate phosphor in which particles of the aluminate phosphor having a primary particle diameter of 0.05 &mgr;m to 30 &mgr;m account for not less than 80 percent by mass is provided by the foregoing method.

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 ?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.