Page 185 - Inventions - A Visual Encyclopedia (DK - Smithsonian)
P. 185
Energy-efficient lights Laser light
■ ■ What? Fluorescent lights ■ ■ What? Laser
■ ■ Who? Edmund Germer, Friedrich Meyer, ■ ■ Who? Theodore H. Maiman, Arthur
and Hans Spanner Schawlow, Charles Townes, and Gordon Gould
■ ■ Where and when? Germany, 1926 ■ ■ Where and when? US, 1960
In a fluorescent light, electricity is passed A laser is a powerful but very narrow
through vapor of the element mercury, beam of light. It is produced by providing
creating invisible ultraviolet light. When this energy to the atoms of a solid or gas so
hits a fluorescent coating lining the inside they give off light. The atoms work in
of the bulb, it is converted to visible light. step with each other to produce very pure
Early fluorescent lights were large, but in light. Lasers are mainly used for industrial
the 1970s, small compact fluorescent lights purposes, such as carrying information
(CFLs) were developed by the American along fiber-optic cables and sending
engineer Edward E Hammer. Searchlights information into space. AT HOME
■ ■ What? Xenon arc lamp
■ ■ Who? Osram Licht AG
■ ■ Where and when? Germany, 1940s
A type of arc light, a xenon lamp is
filled with high-pressure xenon gas.
CFLs last up When electricity passes through it,
to 15 times the xenon glows brightly. Xenon
longer than lamps are used in movie projectors,
incandescent
light bulbs. searchlights, lighthouses, and to create
the most powerful light beam in the
world—on top of the Luxor Hotel in Lasers can be used to spectacular
Las Vegas (above). effect at concerts
LEDs
■ ■ What? Light-emitting diodes (LEDs)
■ ■ Who? Nick Holonyak, Jr.
■ ■ Where and when? US, 1962
Because they use less energy, last
longer, and are less fragile, LEDs have
begun to replace incandescent bulbs
in recent times. LEDs work by jiggling
the electrons in a material known as
a semiconductor, such as silicon, so
that an electric current flows, creating
light. LED bulbs can be very small—
they are used for the tiny lights seen
on power buttons on remote controls.
Colored decorative lights
are often LEDs.
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