Halogen Lamp
One invention that focussed primarily on the problem of very short lamp life was the halogen lamp. It was also known as the tungsten-halogen lamp, the quartz-halogen lamp or the quartz-iodine lamp, wherein a tungsten filament is sealed into a small envelope filled with a halogen gas such as iodine or bromine. In an ordinary incandescent lamp, the thickness of the filament may vary minutely. The resistance of the filament is higher at the portions where the filament is the thinnest, which causes the thin areas to be hotter than the thicker parts of the filament. The rate evaporation of tungsten is much higher at these points due to the increased temperature thereby causing the thin areas to become even thinner, thus creating a runaway effect until the filament fails. The envelope material can be modified to achieve the required lamp characteristics. Halogen bulbs are widely used in the automobile industry and because headlamps often contain plastic parts, halogen headlamp bulbs' envelopes are made out of hard glass, or out of quartz 'doped' with additives to block most of the UV output.
Conversely, some applications require the ultraviolet radiation, then in such cases, the lamp envelope is made out of the undoped quartz. Thus, the lamp does become a source of UV-B radiation. The undoped quartz halogen lamps are used in some scientific, medical and dental instruments as a UV-B source.
The halogen bulb is very similar to the light bulb, it consists of a filament that is made of from tungsten. In any ordinary bulb, the argon gas is filled, however with a halogen bulb it is filled with halogen gas. The halogen gas allows the removal of the carbon that has been deposited on the inside of the bulb. This carbon is produced when the tungsten filament heats up and the carbon is removed and with the help of halogen gas, it redistributes the carbon back onto the filter, which would in turn allows for burning at a much higher temperature and ultimately this entire process does provide a whiter, brighter and a better light.
Since the halogen bulb is much smaller in size, the halogen lamp exactly proportionate to the size of the bulb. Often a halogen lamp is designed to be utilized in very small compact areas.
There are many manifold benefits of utilizing halogen lamps and the most important among them is energy conservation. A halogen lamp has the ability to provide the same kind of power as comparable to any other conventional lamp and yet consume much less energy. Additionally, a halogen lamp bulb has a very long life span. That life span can range anywhere from 2,000 to 4,000 hours depending on the usage.