The earliest means of artificial lighting were the open fire, firebrands, and torches. The first lamp was a dish of stone (later of clay, pottery, or metal) containing vegetable or animal oil and a wick. This was succeeded by the candle, first made of wax and later also of tallow, and by the lantern, which is of early origin. The Argand burner was an improved oil lamp with a burner and a chimney, and this type of lamp was widely used after the Canadian geologist Abraham Gesner popularized the use of kerosene.
Coal gas was first used as an illuminant in the late 18th cent. by the engineer William Murdock in England and by the engineer Philippe Lebon in Paris. It was used in London in 1802, in Baltimore in 1817, and in New York state in 1823. The invention of the Bunsen burner by the German chemist Robert Wilhelm Bunsen and the invention of the Welsbach mantle, a device developed by the Austrian scientist Carl von Welsbach that gives off bright light when placed over a flame, greatly stimulated the use of gas for lighting purposes.
The first development in electric lighting was the arc lamp, which was evolved from the carbon-arc lamp demonstrated in 1801 by Sir Humphry Davy, in which an electric current bridges a gap between two carbon rods and forms a bright discharge called an arc. Early lamps of this type were made with an open arc; later ones were enclosed in glass and thus made more practicable. Carbon-arc street lamps, first produced by the American scientist Charles F. Brush, were used in Cleveland in 1879 and soon came into wide use in other cities. The mercury-vapor electric lamp was devised by the American inventor Peter Cooper Hewitt in 1903. This type of lamp makes use of a pool of mercury liquid in a condition of high vacuum; when an electric current passes through the mercury it produces ionized vapor, which gives off a blue-green light. Modern improvements have given this lamp a much greater efficiency. The neon lamp, developed by the French physicist Georges Claude in 1911, has been largely used in commercial signs.The Incandescent Lamp
The incandescent electric lamp, in which an electric current passing through a resistance filament (e.g., one of carbon and tungsten) enclosed in a vacuum tube heats the filament until it glows, was developed by the American electrician Moses G. Farmer in 1858-59 but was not practicable. Sir Joseph Swan in England and Thomas Edison in the United States, working independently, developed lamps of this kind; the lamp patented by Edison in 1879 was the first widely marketed incandescent lamp and was the forerunner of the modern Mazda lamp that utilizes a filament of drawn tungsten hermetically sealed in a glass envelope. A gas-filled incandescent lamp was invented by the American chemist Irving Langmuir in 1913.The Fluorescent Lamp
The French physicist A. E. Becquerel constructed a fluorescent lamp and described (1867) the preparation of fluorescent tubes basically similar to those made today. Considerable progress in developing fluorescent lighting was made in several European countries, and during the 1920s high-voltage fluorescent tubes were used in advertising signs. In the United States the first practical hot-cathode, low-voltage fluorescent lamp was marketed in 1938. This is the form of lamp still commonly used. It consists of a long, sealed glass tube with an electrode at each end; a small amount of mercury is contained within the tube. The inside surface of the tube is coated with a mixture of fluorescent powders. When an electric current is maintained through the lamp, the mercury becomes vaporized and gives off invisible ultraviolet radiation that is absorbed by the fluorescent coating. The coating then emits visible light. The fluorescent lamp is often easily distinguished by its tubular design—straight, circular, or bent in a U or other shape. Compact fluorescent lamps, usually designed to screw into the socket originally made for an incandescent lamp, are now also shaped to resemble the less efficient incandescent lamps that they are intended to replace.Contemporary Lighting Technology
The search for efficient artificial lighting during the 20th cent. first focused on improving incandescent lamp technology and high-intensity discharge (HID) lamps. The tungsten-halogen lamp, like the other incandescent lamps, uses a tungsten filament as the light source, a gas filling that includes a halogen, and a quartz bulb. The halogens prevent lamp walls from darkening as quickly as those of the other incandescent lamps, so more light is available to the task or work surface. HID is the term commonly used to designate four distinct types of lamps—mercury vapor, metal halide, high-pressure sodium, and low-pressure sodium—that actually have very little in common. The mercury vapor lamp produces light when the electrical current passes through a small amount of mercury vapor. The color rendering qualities of the mercury vapor lamp are not as good as those of incandescent and fluorescent lamps. The metal halide lamp is similar to the mercury vapor lamp, the major difference being that the metal halide lamp contains various metal halide additives in addition to mercury vapor. The efficiency of metal halide lamps is twice that of mercury vapor lamps. Some of the newer metal halide lamps provide color similar to that of incandescent lamps while others emulate daylight. The high-pressure sodium (HPS) lamp has the highest lamp efficiency of all lamps commonly used indoors. It produces a golden-white light when electricity passes through a sodium vapor. The low-pressure sodium (LPS) lamp, the most efficient of all, is used where color is not important because all colors illuminated by an LPS light source appear as tones of gray or yellow.
The most promising technology is that of the light-emitting diode (LED). A tiny semiconductor microchip, an LED consumes little power, is long lasting, and is relatively inexpensive. It produces visible or infrared light when subjected to an electric current. First demonstrated in 1962 and appearing in a commercial product in 1968, LEDs were limited to small applications until 1985, when more powerful LEDs were produced. Their major limitation was that only red and green microchips were possible. However, in 1993, researchers at several universities in the United States and Japan developed an LED that produced blue light that, in conjunction with the red and green chips, could produce white light; this made the LED a major player in illumination technology. Subsequently, the discovery of organic light-emitting diodes (OLEDs), made with plastics rather than silicon and other traditional semiconductor materials, opened the door for many specialty applications under the mantle of solid-state lighting.Functional Selection of Lighting
The incandescent lamp can be considered the basic light source, because it is the one in most common use. While the least expensive to buy, it is the most expensive to own due to its low efficiency and relatively short life. The fluorescent lamp is the second most common light source. It is widely used in factories, offices, stores, and public buildings because it produces far more light for the same expenditure of electricity than do incandescent lamps. Compact fluorescent bulbs that can act as replacements for standard incandescent bulbs are sold for their long life and energy efficiency. However, to many observers the colors of objects illuminated by a fluorescent lamp often appear quite different than they would appear if the objects were illuminated by an incandescent lamp or sunlight. Sodium vapor lamps are used on some highways, as are color-corrected mercury-vapor discharge lamps. Tungsten-halogen lamps are used for lighting sports arenas and stadiums, in automobile headlights, and for residential lighting. Xenon lamps are used in flash photography as well as in cinema projectors and lighthouses.
Lighting includes both artificial light sources such as lamps and natural illumination of interiors from daylight. Daylighting (trough windows, skylights, etc.) is often used as the main source of light during daytime in buildings given its low cost. Lighting represents a major component of energy consumption, accounting for a significant part of all energy consumed worldwide. Artificial lighting is most commonly provided today by electric lights, but gas lighting, candles, or oil lamps were used in the past, and still are used in certain situations. Proper lighting can enhance task performance or aesthetics, while there can be energy wastage and adverse health effects of lighting. Indoor lighting is a form of fixture or furnishing, and a key part of interior design. Lighting can also be an intrinsic component of landscaping.
Proper selection of fixtures is complicated by the requirement to minimize the veiling reflections off printed material. Since the exact orientation of printed material may not be closed controlled, a visual comfort probability can be calculated for a given set of lighting fixtures.
Lighting is classified by intended use as general, localized, or task lighting, depending largely on the distribution of the light produced by the fixture.
Forms of Lighting include alcove lighting, which like most other uplighting is indirect. This is often done with fluorescent lighting or rope light, or occasionally with neon lighting. It is a form of backlighting.
Soffit or close to wall lighting can be general or a decorative wall-wash, sometimes used to bring out texture (like stucco or plaster) on a wall, though this may also show its defects as well. The effect depends heavily on the exact type of lighting source used.
Recessed lighting (often called "pot lights" in Canada, "can lights" or 'high hats" in the U.S.) is popular, with fixtures mounted into the ceiling structure so as to appear flush with it. These downlights can use narrow beam spotlights, or wider-angle floodlights, both of which are bulbs having their own reflectors. There are also downlights with internal reflectors designed to accept common 'A' lamps (light bulbs) which are generally less costly than reflector lamps. Downlights can be incandescent, fluorescent, HID (high intensity discharge) or LED, though only reflector incandescent or HID lamps are available in spot configuration.
Track lighting, invented by Lightolier, was popular at one point because it was much easier to install than recessed lighting, and individual fixtures are decorative and can be easily aimed at a wall. It has regained some popularity recently in low-voltage tracks, which often look nothing like their predecessors because they do not have the safety issues that line-voltage systems have, and are therefore less bulky and more ornamental in themselves. A master transformer feeds all of the fixtures on the track or rod with 12 or 24 volts, instead of each light fixture having its own line-to-low voltage transformer. There are traditional spots and floods, as well as other small hanging fixtures. A modified version of this is cable lighting, where lights are hung from or clipped to bare metal cables under tension.
A sconce is a wall-mounted fixture, particularly one that shines up and sometimes down as well. A torchiere is an uplight intended for ambient lighting. It is typically a floor lamp but may be wall-mounted like a sconce.
The portable or table lamp is probably the most common fixture, found in many homes and offices. The standard lamp and shade that sits on a table is general lighting, while the desk lamp is considered task lighting. Magnifier lamps are also task lighting.
The illuminated ceiling was once popular in the 1960s and 1970s but fell out of favor after the 1980s. This uses diffuser panels hung like a suspended ceiling below fluorescent lights, and is considered general lighting. Other forms include neon, which is not usually intended to illuminate anything else, but to actually be an artwork in itself. This would probably fall under accent lighting, though in a dark nightclub it could be considered general lighting. Underwater accent lighting is also used for koi ponds, fountains, swimming pools and the like.
In a movie theater each step in the aisles is usually marked with a row of small lights, for convenience and safety when the film has started, hence the other lights are off. Traditionally made up of small low wattage, low voltage lamps in a track or translucent tube, these are rapidly being replaced with LED based versions.
In addition to lighting for useful purposes, and early 1970s, manufacturers would sometimes backlight their logos and or other translucent panelling. In the 1990s, a popular trend was to customize vehicles with neon lighting, especially underneath the body of a car. In the 2000s, neon lighting is increasingly yielding to digital vehicle lighting, in which bright LEDs are placed on the car and operated by a computer which can be customized and programmed to display a range of changing patterns and colors, a technology borrowed from Christmas lights.
Lighting design as it applies to the built environment, also known as 'architectural lighting design', is both a science and an art. Comprehensive lighting design requires consideration of the amount of functional light provided, the energy consumed, as well as the aesthetic impact supplied by the lighting system. Some buildings, like surgical centers and sports facilities, are primarily concerned with providing the appropriate amount of light for the associated task. Some buildings, like warehouses and office buildings, are primarily concerned with saving money through the energy efficiency of the lighting system. Other buildings, like casinos and theatres, are primarily concerned with enhancing the appearance and emotional impact of architecture through lighting systems. Therefore, it is important that the sciences of light production and luminaire photometrics are balanced with the artistic application of light as a medium in our built environment. These electrical lighting systems should also consider the impacts of, and ideally be integrated with, daylighting systems. Factors involved in lighting design are essentially the same as those discussed above in energy conservation analysis.
Mathematical modeling is normally used for complex lighting design, whereas, for simple configurations, tables and simple hand calculations can be used. Based on the positions and mounting heights of the fixtures, and their photometric characteristics, the proposed lighting layout can be checked for uniformity and quantity of illumination. For larger projects or those with irregular floor plans, lighting design software can be used. Each fixture has its location entered, and the reflectance of walls, ceiling, and floors can be entered. The computer program will then produce a set of contour charts overlaid on the project floor plan, showing the light level to be expected at the working height. More advanced programs can include the effect of light from windows or skylights, allowing further optimization of the operating cost of the lighting installation.
The Zonal Cavity Method is used as a basis for both hand, tabulated, and computer calculations. This method uses the reflectance coefficients of room surfaces to model the contribution to useful illumination at the working level of the room due to light reflected from the walls and the ceiling. Simplified photometric values are usually given by fixture manufacturers for use in this method.
Computer modelling of outdoor flood lighting usually proceeds directly from photometric data. The total lighting power of a lamp is divided into small solid angular regions. Each region is extended to the surface which is to be lit and the area calculated, giving the light power per unit of area. Where multiple lamps are used to illuminate the same area, each one's contribution is summed. Again the tabulated light levels (in lux or foot-candles) can be presented as contour lines of constant lighting value, overlaid on the project plan drawing. Hand calculations might only be required at a few points, but computer calculations allow a better estimate of the uniformity and lighting level.
Practical lighting design must take into account the gradual decrease in light levels from each lamp owing to lamp aging, lamp burnout, and dirt accumulation on fixture and lamp surfaces. Empirically-established depreciation factors are listed in lighting design handbooks.
Specification of illumination requirements is the basic concept of deciding how much illumination is required for a given task. Clearly, much less light is required to illuminate a hallway or bathroom compared to that needed for a word processing work station. Prior to 1970 (and too often even today), a lighting engineer would simply apply the same level of illumination design to all parts of the building without considering usage. Generally speaking, the energy expended is proportional to the design illumination level. For example, a lighting level of 80 footcandles might be chosen for a work environment involving meeting rooms and conferences, whereas a level of 40 footcandles could be selected for building hallways. If the hallway standard simply emulates the conference room needs, then twice the amount of energy will be consumed as is needed for hallways. Unfortunately, most of the lighting standards even today have been specified by industrial groups who manufacture and sell lighting, so that a historical commercial bias exists in designing most building lighting, especially for office and industrial settings. Beyond the energy factors being considered, it is important not to over-design illumination, lest adverse health effects such as headache frequency, stress, and increased blood pressure be induced by the higher lighting levels. In addition, glare or excess light can decrease worker efficiency.
Analysis of lighting quality particularly emphasizes use of natural lighting, but also considers spectral content if artificial light is to be used. Not only will greater reliance on natural light reduce energy consumption, but will favorably impact human health and performance. For example, it is clear that student test scores are improved for children who learn in the presence of greater natural light. Artificial night-lighting has been associated with irregular menstrual cycles.
Kerosene and Whale Oil Lamps
In 1849, Dr. Abraham Gesner, a Canadian geologist, devised a method where kerosene could be distilled from petroleum. Earlier coal-gas methods had been used for lighting since the 1820s, but they were expensive. Gesner's kerosene was cheap, easy to produce, could be burned in existing lamps, and did not produce an offensive odor as did most whale oil. It could be stored indefinitely, unlike whale oil, which would eventually spoil. The American petroleum boom began in the 1850s. By the end of the decade there were 30 kerosene plants operating in the United States. The cheaper, more efficient fuel began to drive whale oil out of the market. John D. Rockefeller was most responsible for the commercial success of kerosene. He set up a network of kerosene distilleries which would later become Standard Oil, thus completely abolishing the need for Whale Oil lamps.
Compact fluorescent lamps
Compact fluorescent lamps (aka 'CFLs') use less power to supply the same amount of light as an incandescent lamp. Due to the ability to reduce electric consumption, many organizations have undertaken measures to encourage the adoption of CFLs. Some electric utilities and local governments have subsidized CFLs or provided them free to customers as a means of reducing electric demand. For a given light output, CFLs use between one fifth and one quarter of the power of an equivalent incandescent lamp. One of the simplest and quickest ways for a household or business to become more energy efficient is to adopt CFLs as the main lamp source, as suggested by the Alliance for Climate Protection
The International Association of Lighting Designers (IALD) is an organization which focuses on the advancement of lighting design education and the recognition of independent professional lighting designers. Those fully independent designers who meet the requirements for professional membership in the association typically append the abbreviation IALD to their name.
The Professional Lighting Designers Association (PLDA), formerly known as ELDA is an organisation focusing on the promotion of the profession of Architectural Lighting Design. They publish a monthly newsletter and organise different events throughout the world.
The National Council on Qualifications for the Lighting Professions (NCQLP) offers the Lighting Certification Examination which tests rudimentary lighting design principles. Individuals who pass this exam become ‘Lighting Certified’ and may append the abbreviation LC to their name. This certification process is one of three national (U.S.) examinations (the others are CLEP and CLMC) in the lighting industry and is open not only to designers, but to lighting equipment manufacturers, electric utility employees, etc. Generally speaking there is no legal or practical requirement for the lighting design team to possess the certifications discussed.
The Professional Lighting And Sound Association (PLASA) is a UK-based trade organisation representing the 500+ individual and corporate members drawn from the technical services sector. Its members include manufacturers and distributors of stage and entertainment lighting, sound, rigging and similar products and services, and affiliated professionals in the area. They lobby for and represent the interests of the industry at various levels, interacting with government and regulating bodies and presenting the case for the entertainment industry. Example subjects of this representation include the ongoing review of radio frequencies (which may or may not affect the radio bands in which wireless microphones and other devices use) and engaging with the issues surrounding the introduction of the RoHS (Reduction of Hazardous Substances) regulations.
Indian Society of Lighting Engineers (ISLE) is a society in India, which has various professionals such as physicists, lighting engineers, architects, medical professionals and ophthalmologists, light source and fitting manufacturers. ISLE promotes lighting education, helps research and exchange of information and knowledge among the professionals.
ISLE has introduced courses on Lighting Design, Engineering and Architecture in Manipal Institute of Technology, Manipal (Karnataka), Jadhavpur University, Kolkata, (West Bengal) School of Planning and Architecture, New Delhi and Maeer Institute of Technology, Pune, (Maharashtra).
ISLE Karnataka State Center has organized in cooperation with the European Union under the EU ASIA INVEST program a series of training programs in the field of Street Lighting and Outdoor Lighting, which is of particular interest to the municipalities and to tourism developers, with emphasis on techniques, standards, energy conservation, safety, and security.