| A halogen lamp is an incandescent lamp in which a tungsten filament is sealed into a compact transparent capsule filled with an inert gas and a small amount of halogen such as iodine or bromine. The combination of the halogen gas and the tungsten filament produces a chemical reaction known as a halogen cycle which increases the lifetime of the bulb and prevents its darkening by redepositing tungsten from the inside of the bulb back onto the filament. The halogen lamp “burns” at a higher temperature than a standard gas filled lamp of similar power without loss of operating life. This gives it a higher efficacy (10-30 lm/W) and is therefore more efficient than a standard tungsten lamp. It also gives light of a higher color temperature compared to a non-halogen incandescent lamp (typically 3000ºK). Because of their smaller size, halogen lamps can advantageously be used with optical systems that are more efficient meaning more light is emitted from the luminaire making the whole installation more efficient. |