Lamps

A light fixture is an electrical device used to create artificial light or illumination. A luminaire is a lighting fixture complete with the light source or lamp, the reflector for directing the light, an aperture (with or without a lens), the outer shell or housing for lamp alignment and protection, an electrical ballast, if required, and connection to a power source. A wide variety of special light fixtures are created for use in the automotive industry, aerospace, marine and medicine. Light fixtures are classified by how the fixture is installed, the light function or lamp type.

The background light is used to illuminate the background area of a set. The background light will also provide separation between the subject and the background. In the standard 4-point lighting setup, the background light is placed last and is usually placed directly behind the subject and pointed at the background. In film, the background light is usually of lower intensity. More than one light could be used to light uniformly a background or alternatively to highlight points of interest. Also, the light that all these gave was poor and this was not solved until the introduction of electric lighting in mines around 1900. But it took until 1930 for the introduction of battery-powered helmet lamps to finally solve the problem.

Black light fluorescent tubes are typically made in the same fashion as normal fluorescent lights except that only one phosphor is used and the normally clear glass envelope of the bulb may be replaced by a deep-bluish-purple glass called Wood's glass, a nickel-oxide–doped glass, which blocks almost all visible light above 400 nanometers. In practice, partly due to cost but mainly because Wood's glass does not make a satisfactory material for lamp manufacture, the lamp will be made from normal glass and a relatively thin coating of a UV filtering material is applied to the exterior. The color of such lamps is often referred to in the trade as "blacklight blue" or "BLB." This is to distinguish these lamps from "bug zapper" blacklight ("BL") lamps that don't have the filter material.

The first safety lamp was invented by William Reid Clanny, an Irish physician, who announced his discovery on May 20th, 1813 at the Royal Society of Arts in London, but it was not tried out in a colliery until 1815. Within months of this demonstration, two improved designs had been announced: one by George Stephenson, which later became the Geordie lamp, and the Davy lamp, invented by Sir Humphry Davy. Most later lamps are constructed on the principle discovered by Davy, that a flame enveloped in wire gauze of a certain fineness does not ignite firedamp Both the Davy and Stephenson lamps were fragile. The gauze in the Davy quickly rusted in the moist air of a coal pit, and so became unsafe, while the glass in the Stephenson was easily broken, and could then allow the flame to ignite firedamp in the atmosphere. Later designs, the Gray, Mueseler, Marsaut, and other lamps, tried to overcome these problems by using multiple gauze cylinders, but the glass remained a problem until toughened glass became available.