A halogen lamp, also known as a tungsten halogen, quartz-halogen or quartz iodine lamp, is an incandescent lamp that has a small amount of halogen such as iodine or bromine added. The combination of the halogen gas and the tungsten filament produces a halogen cycle chemical reaction which redeposits evaporated tungsten back onto the filament, increasing its life and maintaining the clarity of the envelope. Because of this, a halogen lamp can be operated at a higher temperature than a standard gas-filled lamp of similar power and operating life, producing light of a higher luminous efficacy and color temperature. The small size of halogen lamps permits their use in compact optical systems for projectors and illumination.
- Halogen Lamps are small, lightweight
- Low cost to produce
- Does not use mercury like CFLs(fluorescent) or mercury vapor lights
- Better color temperature than standard tungsten (2800-3400 Kelvin), it is closer to sunlight than the more “orangy” standard tungsten.
- Longer life than a conventional incandescent
- Instant on to full brightness, no warm up time, and it is dimmable
- Extremely hot (easily capable of causing severe burns if the lamp is touched).
- The lamp is sensitive to oils left by the human skin, if you touch the bulb with your bare hands the oil left behind will heat up once the bulb is activated, this oil may cause an imbalance and result in a rupture of the bulb.
- Explosion, the bulb is capable of blowing and sending hot glass shards outward. A screen or layer of glass on the outside of the lamp can protect users.
- Not as efficient as HID lamps (Metal Halide and HPS lamps)
Variations and Uses
The halogen bulb comes in two basic configurations: single and double ended. The most common halogen lamps are double ended, these generally are the larger wattage lamps and are used for work lights, yard lights and film production lamps. The halogen lamp has an instant ‘on’ ability unlike mercury vapor or high pressure sodium, therefore they work well for security lamps that are activated by motion sensors. The life of a halogen lamp is shortened by frequent on and off cycles.
Filaments in a doubled ended halogen may be straight or double coiled. All filaments are coiled to increase brightness, this was a development by Irving Langmuir in the standard incandescent bulb.