Abstract: Metal halide lamps having better lumen maintenance over the life of the lamp contain metal frame parts whose surface is oxidized either prior to lamp assembly or oxidized in-situ during operation of the lamp by oxygen or an oxidizing agent present inside the outer vitreous envelope.

Abstract: A lighting unit having a filament serving as a supplementary light source, an improved gas discharge tube serving as a main light source having improved electrodes and an improved ballast circuit operating in cooperation with the improved electrodes is disclosed. Various embodiments of the improved electrodes and various embodiments of the improved ballast circuits are disclosed. The improved ballast circuit operating in cooperation with the improved electrodes provides for thermionic arc conditions in the operation of the gas discharge tube substantially immediately after the application of voltage applied to the unit.

Abstract: The coating on the inside of a metal halide lamp for promoting the formation of a liquid condensate film consists of particles of a refractory oxide in generally block-like or spherical or fiber-like shapes. Block-like or spherical particles should be laid down as monolayers with the distances between particles being of the order of the particle dimensions. Fiber-like particles may be also laid down as a monolayer or, alternatively, in a coating several diameters thick to form "fiber piles" having a free volume for holding liquid which is much greater than the volume of the fibers.

Abstract: The coating on the inside of a metal halide lamp for promoting the formation of a liquid condensate film consists of particles of a refractory oxide in generally block-like or spherical or fiber-like shapes. Block-like or spherical particles should be laid down as monolayers with the distances between particles being of the order of the particle dimensions. Fiber-like particles may be also laid down as a monolayer or, alternatively, in a coating several diameters thick to form "fiber piles" having a free volume for holding liquid which is much greater than the volume of the fibers.

Abstract: Color correction means for flash lamp are disclosed which utilizes a blue emitting organic phosphor medium to increase the total light output being emitted from the flash lamp and lower the Spectral Distribution Index (SDI) of the lamp-phosphor combination. The phosphor medium can be employed as a coating for the light-transmitting envelope of the flash lamp wherein the phosphor constituent is dissolved in a transparent film forming polymer. In certain preferred embodiments, further color correction of the flash lamp radiation can be effected with dyes incorporated into the protective cover means or containment lacquer now commonly employed.