The History of Fluorescent Lamps
Fluorescent lamps were inspired by the study of fluorescent and phosphorescent materials found in nature. From the short-lived glow of the Geissler tubes developed in the 1850s to the long lasting and energy-efficient compact fluorescent lamps (CFLs) of 2009, fluorescent lamps provide a useful alternative to incandescent lamps.
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Discovery
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In an 1852 paper, Sir George Stokes coined the term fluorescence, inspired by the mineral fluorite which glows naturally after it's exposed to light. Stokes believed the glow was caused by the conversion of ultra-violet radiation into visible light by the mineral. His theory was used to help explain the glow that scientists observed occurring in tubes with a partial vacuum when electric current passed through.
Early Development
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Early development of the fluorescent lamp began when Henry Geissler developed a vacuum tube in 1856 that glowed at one end when electricity passed through it. In 1859 Alexandre Becquerel added coatings of luminescent materials to the surfaces of the Geissler tubes, which caused them to fluoresce. The study of these phenomena resulted in the invention of the fluorescent lamp.
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Mercury Vapor Lamps
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Peter Cooper Hewitt invented the mercury-vapor lamp in 1901. This lamp glowed with an unappealing blue-green light that limited its use. However, the mercury-vapor lamp used a ballast that was instrumental in the design of the fluorescent lamp. It was also more energy-efficient than incandescent lamps of the time. The development of neon lights also contributed to the design of early fluorescent lamps, providing an improved electrode in 1915 and fluorescent coatings in 1926.
General Electric
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General Electric (GE) took over development of the fluorescent lamp in the 1930s after gaining control of the relevant patents. The two main groups that worked on fluorescent lamp development at GE were George Inman's and P. J. Pritchard's, both based in Cleveland, Ohio. They designed bulbs that varied in size from 18 inches to four feet, and developed better ballasts and circuits. Fluorescent lighting was publicized through its use at the 1939 New York World's Fair, and came into high demand during World War II to light factories for the war effort.
CFLs
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Compact fluorescent lamps were invented in 1976 by GE's Edward Hammer, but were not put into production at that time because of prohibitive start up costs. The new compact fluorescent lamps used an innovative design with a spiral shaped tube to make them resemble the shape and size of incandescent light bulbs. This enabled them to fit in the same space so they could be used instead of incandescent bulbs. These bulbs use 13 to 25 watts of energy instead of the 60 to 100 watts common to incandescent bulbs and last much longer, making them more energy-efficient.
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