The halogen lamp first entered the U.S. market in 1957. Halogen bulbs were a refinement of regular light bulbs, offering up to 20 percent more energy efficiency, a longer life and better light quality. The light from halogen lamps looks whiter and brighter than regular lamps, because it has higher color temperatures and its output consists of more blues and greens.
Both the halogen lamp and the incandescent light contain a filament made from tungsten. But the halogen is encased in a much smaller quartz envelope that contains halogen gas, which combines with the tungsten atoms as it evaporates and redeposits them on the filament. This recycling process is a main reason why the halogen filament lasts longer.
One downside of the halogen lamp, as compared to the regular lamp, is that halogen light bulbs get hot, dangerously hot. Even though these high temperatures are essential to the operation of halogen lamps (they result from a smaller envelope surface which is closer to the light bulb's filament), they do present fire and burn hazards to those using them. These hazards have spurred the enactment of building safety measures in some areas. In some communities, very powerful halogen bulbs are banned altogether.
While it may be hard to believe, another possible danger of the halogen lamp is that it can cause sunburns. Overexposure to the ultra-violet rays(UV) emitted by an uncovered quartz halogen lamp can actually damage the skin. To prevent that, most halogen lamps usually have a UV-absorbing glass filter over or around the bulb. This covering also helps minimize the scattering of hot bulb pieces if the bulb bursts.
While halogen lamps typically cost more than regular bulbs, they generally last much longer, about 2,000 to 4,000 hours. A regular light bulb lasts about 750 to 1,000 hours in normal use. Halogen also offers you a whiter, brighter light.
Today, the lamps are used in automobile headlights, spotlights, and floodlights and are often preferred for use in restaurants as well as private homes. The halogen lamp is also increasingly common in hospital emergency wards, and in operating rooms. Because the halogen light itself is so small, they are even being used with optical systems now to make them more efficient.
