40
PHYSICS OF THE IMPOSSIBLE
exist, depending on the material that lases and the energy that is injected into the material (e.g., electricity, intense beams of light, even
chemical explosions). Among them are
• Gas lasers. These lasers include helium-neon lasers,
which are very common, creating a familiar red beam. They
are energized by radio waves or electricity. Helium-neon
lasers are quite weak. But carbon dioxide gas lasers can be
used for blasting, cutting, and welding in heavy industry and
can create beams of enormous power that are totally invisible.
• Chemical lasers. These powerful lasers are energized
by a chemical reaction, such as a burning jet of ethylene and
nitrogen trifluoride, or NF 3 . Such lasers are powerful
enough to be used in military applications. Chemical lasers
are used in the U.S. military's airborne and ground lasers,
which can produce millions of watts of power, and are designed to shoot down short-range missiles in midflight.
• Excimer lasers. These lasers are also powered by
chemical reactions, often involving an inert gas (e.g., argon,
krypton, or xenon) and fluorine or chlorine. They produce
ultraviolet light and can be used to etch tiny transistors onto
chips in the semiconductor industry, or for delicate Lasik
eye surgery.
• Solid-state lasers. The first working laser ever made
consisted of a chromium-sapphire ruby crystal. A large variety of crystals will support a laser beam, in conjunction
with yttrium, holmium, thulium, and other chemicals. They
can produce high-energy ultrashort pulses of laser light.
• Semiconductor lasers. Diodes, which are commonly
used in the semiconductor industry, can produce the intense beams used in industrial cutting and welding. They
are also often found in checkout stands in grocery stores,
reading the bar codes of your grocery items.
• Dye lasers. These lasers use organic dyes as their me-
PHYSICS OF THE IMPOSSIBLE
exist, depending on the material that lases and the energy that is injected into the material (e.g., electricity, intense beams of light, even
chemical explosions). Among them are
• Gas lasers. These lasers include helium-neon lasers,
which are very common, creating a familiar red beam. They
are energized by radio waves or electricity. Helium-neon
lasers are quite weak. But carbon dioxide gas lasers can be
used for blasting, cutting, and welding in heavy industry and
can create beams of enormous power that are totally invisible.
• Chemical lasers. These powerful lasers are energized
by a chemical reaction, such as a burning jet of ethylene and
nitrogen trifluoride, or NF 3 . Such lasers are powerful
enough to be used in military applications. Chemical lasers
are used in the U.S. military's airborne and ground lasers,
which can produce millions of watts of power, and are designed to shoot down short-range missiles in midflight.
• Excimer lasers. These lasers are also powered by
chemical reactions, often involving an inert gas (e.g., argon,
krypton, or xenon) and fluorine or chlorine. They produce
ultraviolet light and can be used to etch tiny transistors onto
chips in the semiconductor industry, or for delicate Lasik
eye surgery.
• Solid-state lasers. The first working laser ever made
consisted of a chromium-sapphire ruby crystal. A large variety of crystals will support a laser beam, in conjunction
with yttrium, holmium, thulium, and other chemicals. They
can produce high-energy ultrashort pulses of laser light.
• Semiconductor lasers. Diodes, which are commonly
used in the semiconductor industry, can produce the intense beams used in industrial cutting and welding. They
are also often found in checkout stands in grocery stores,
reading the bar codes of your grocery items.
• Dye lasers. These lasers use organic dyes as their me-