High-intensity discharge lamps (HID lamps) are a type of electrical gas-discharge lamp which produces light by means of an electric arc between tungsten electrodes housed inside a translucent or transparent fused quartz or fused alumina arc tube. This tube is filled with both gas and metal salts. The gas facilitates the arc's initial strike. Once the arc is started, it heats and evaporates the metal salts forming plasma, which greatly increases the intensity of light produced by the arc and reduces its power consumption. High-intensity discharge lamps are a type of arc lamp. High-intensity discharge lamps make more visible light per unit of electric power consumed than fluorescent and incandescent lamps since a greater proportion of their radiation is visible light in contrast to infrared. Applications HID lamps are typically used when high levels of light over large areas are required, and when energy efficiency and/or light intensity are desired. These areas include gymnasiums, large public areas, warehouses, movie theaters, football stadiums,outdoor activity areas, roadways, parking lots, and pathways. More recently, HID lamps have been used in small retail and even residential environments because of advances in reduced lumen bulbs. Ultra-High Performance (UHP) HID lamps are used in LCD or DLP projection TV sets or projection displays as well. HID lamps have made indoor gardening practical, particularly for plants that require high levels of direct sunlight in their natural habitat; HID lamps, specifically metal halide and high-pressure sodium, are a common light source for indoor gardens. They are also used to reproduce tropical intensity sunlight for indoor aquaria. Most HID lamps produce significant UV radiation, and require UV-blocking filters to prevent UV-induced degradation of lamp fixture components and fading of dyed items illuminated by the lamp. Exposure to HID lamps operating with faulty or absent UV-blocking filters causes injury to humans and animals, such as sunburn and arc eye. Many HID lamps are designed so as to quickly extinguish if their outer UV-shielding glass envelope is broken. Beginning in the early 1990s, HID lamps have seen applications in automotive headlamps. Xenon or High-Intensity Discharge (HID) lighting provides brighter headlights and increases visibility of many peripheral objects (i.e., street signs and pedestrians) left in the shadows by standard halogen lighting. HID lamps are used in high-performance bicycle headlamps as well as flashlights and other portable lights, because they produce a great amount of light per unit of power. As the HID lights use less than half the power of an equivalent tungsten-halogen light, a significantly smaller and lighter-weight power supply can be used. HID lamps are also used in lamps for underwater diving. The higher efficacy of HID lamps compared to halogen units means longer burn times for a given battery size and light output. Sumber : Wikipedia
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. Advantages: 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 Disadvantages: 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. .