How Do Halogen Lights Work

Halogen bulbs are a special type of light bulb that utilizes different bulb construction and elements from standard light bulbs to achieve longer bulb life and a distinctively brighter or "lighter" glow. Perhaps the most common place to find halogen lamps are in the headlights of certain vehicles. The basic operation of a halogen lamp is the same as a normal light bulb: a halogen lamp contains a filament made of tungsten metal, which is heated up with an electrical current producing incandescence, which is the light that is given off by a very hot object. This contrasts with fluorescent lights, which use a lower degree of heat to excite gases which give off UV light which, in turn, excites a layer of phosphorescent material on the inside of the bulb which glows as visible light.

Normal bulbs have a relatively short life span, since heating up the tungsten filament gradually causes the tungsten to evaporate and deposit itself on the inside of the bulb until the filament becomes so thin that it snaps, causing the bulb to burn out. In halogen lamps, the bulb is filled with a halogen gas such as bromine or iodine. As the tungsten filament is heated to levels higher than normal bulbs, the halogen gas recycles the tungsten and deposits it back on the filament, which extends bulb life and allows the bulb to run at hotter temperatures. As the tungsten is recycled, it tends to be deposited more heavily on the cooler parts of the filament, which eventually causes the hotter parts to thin, and the bulb to burn out.

Since halogen bulbs must run at a hotter temperature than normal bulbs, and gases must be compressed around the filament at a higher amount of pressure in order to make the halogen recycling process work, bulbs cannot be made of normal glass. A typical halogen bulb is made of quartz, which is very strong and has a high melting point. Halogen bulbs are also much smaller than normal light bulbs and essentially consist of a small sheath of quartz around the filament, resulting in a bulb that looks something like a clear Christmas light. Due to the halogen recycling process, halogen bulbs tend not to darken due to use and maintain a very even brightness level throughout their life span, and also produce more light per watt of energy than normal bulbs.