Abstract: An incandescent lamp assembly, such as an automobile headlight, includes a reflector defining a cavity having a reflecting surface, and an incandescent lamp capsule mounted within the reflector. The incandescent lamp capsule, typically a tungsten halogen incandescent lamp capsule, includes a light-transmissive envelope, a filament sealed in the envelope and a fill material including an inert gas and a halogen additive. A specularly reflective coating is formed on a portion of the envelope for reflecting visible light and infrared radiation emitted by the filament and not directed to the reflecting surface of the reflector. The envelope is ellipsoidally shaped, at least in the portion having the reflective coating, so that the reflective coating reflects visible light and infrared radiation emitted by the filament back to the filament. The reflective coating limits glare and increases the operating efficiency of the headlight.

Abstract: An incandescent lamp having an envelope of hardglass. The envelope encloses a tungsten filament and contains a fill material including an inert fill gas and a halogen additive. A coating of silicon dioxide (i.e., silica) is disposed on a substantial portion of the internal surface of the envelope. The silicon dioxide coating prevents the halogen additive from combining with alkaline ions of the hardglass envelope.