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Lasers can do a number of incredible things. Their special qualities make them particularly useful in recording, storing, and transmitting many kinds of information. Lasers also are valuable in such activities as scanning, heating, measuring, and guiding. As a result of their wide use, lasers can be found in equipment used in homes, factories, offices, hospitals, and libraries.

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DVD

Bursts of laser light record music, computer data and other material used as patters of tiny pits in the surface of special discs. The most common of these discs, compact discs (CD’s) and DVD’s, measures about twelve centimeters across. A DVD can hold much more information than a CD can.

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Disc Players

Lasers also read and play back the information recorded on these discs. In a disc player or disc drive, a laser beam reflects off the pattern of pits as the disc spins. Other devices in the player or drive change the reflections into electrical signals, which are translated into music, computer data, motion pictures, and other information. More lasers are used in disc players and drives than in any other product.

Holograms

Laser beams can produce three-dimensional images in a photographic process called holography. The images, recorded on a photographic plate, are known as holograms. They appear in advertising displays, artwork, and jewelers, and some are placed on credit cards to prevent counterfeiting.

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Fiber-Optic Communication

One of the laser’s greatest uses is in the field of fiber-optic communication. This technology converts the electrical signals that represent telephone calls, television pictures, and computer data into pulses (bursts) of laser light. Strands of glass of plastic called optical fibers conduct the light. Such a fiber is about as thin as a human hair. But a single fiber can carry as much information as several thousand copper telephone wires. Laser light is ideal for this technology because it can be focused precisely and because all its power can be introduced into the fiber. Laser light can travel long distances within a fiber without diminishing in intensity. However, a device called a fiber amplifier cab be used to intensify the laser light within the fiber.

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Scanning

Scanning involves the movement of a laser beam across a surface. Scanning beams are often used to read information. Laser scanners are used at checkout counters in many stores. What looks like a line of light is actually a rapidly moving laser beam scanning a bar code. A bar code consists of a pattern of lines and spaces on packages that identifies the product. The scanner reads the pattern and sends information to a computer in the store. The computer identifies the item’s price and sends the information to the register. Scanners keep track of books in libraries, sort mail in post offices, and read account numbers on checks in banks. Laser printers use a scanning laser beam to produce copies of documents.

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Colorful Visual Effects

In entertainment, laser light shows are created with scanning laser beams. These beams can “draw” spectacular patterns of red, yellow, green, and blue light on buildings or other outdoor surfaces. The beams move so rapidly they produce what looks like a stationary picture. Laser scanners also produce colorful visual effects that create excitement at rock concerts.

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Cut and Weld Metals

A laser beam’s highly focused energy can produce a great amount of heat. Industrial lasers, for example, produce beams of thousands of watts of power. They cut and weld metals, drill holes, and strengthen materials by heating them. Industrial lasers also cut ceramics, cloth, and plastics.

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Eye Surgery

In medicine, the heating power of lasers is often used in eye surgery. Laser beams of certain wavelengths can pass through the cornea (front surface of the eye) but cause no pain or damage because the cornea is transparent and does not absorb light. Highly focused beams can pass through the cornea and close off broken blood vessels on the retina. Lasers of a different wavelength can be used to reshape corneas, enabling some people to see clearly without glasses or contact lenses.

Remove Birthmarks and Tattoos

Doctors also use lasers to treat skin disorders, remove birthmarks and tattoos, and shatter gallstones. Laser beams can replace the standard surgical knife, or scalpel, in some operations. The use of lasers permits extraordinary control and precision in cutting tissue and sealing off cuts. Thus, lasers reduce bleeding and damage to nearby tissues.

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Nuclear Energy

In nuclear energy research, scientists use lasers to produce controlled, miniature hydrogen bomb explosions. They focus many powerful laser beams onto a pellet of frozen forms of hydrogen. The intense beams compress (pack down) the pellet and heat it to millions of degrees. These actions cause the pellet’s atoms to fuse (unite) and release energy. This process, called nuclear fusion, may be able to produce enough energy to solve the world’s energy problems. Lasers have produced the tremendous heat needed to create fusion but have not yet produced usable amounts of energy.

Measure Distances

People use lasers to measure distances. An object’s distance can be determined by measuring the time a pulse of laser light takes to reach and reflect back from the object.

Laser Reflectors on the Moon

In 1969 and 1971, United States astronauts placed mirrored devices called laser reflectors on the moon. Using a high-powered laser, scientists measured the distance between the earth and the moon-more than 383,000 kilometers – to within 5 centimeters. They made the measurement by shinning laser light from a telescope on the earth to the reflectors.

Earthquake Warning System

Laser beams directed over long distances also can detect small movements of the ground. Such measurements help geologists involved in earthquake warning systems. Laser devices used to measure shorter distances are called range finders. Surveyors use range finders to obtain information needed to make maps. Military personnel use them to determine the distance to an enemy target.

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Weightless Strings

A laser’s strong, straight beam makes it a valuable tool for guidance. For example, construction workers use laser beams as “weightless strings” to align the walls and ceilings of a building and to lay straight sewer and water pipes.

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Incredible Uses of Lasers

Instrument called laser gyroscopes use laser beams to detect changes in direction. These devices help ships, airplanes, and guided missiles stay on course. Another military use of lasers is in a guidance device called a target designator. A person using the device aims a laser beam at an enemy target. Missiles, artillery shells, and bombs equipped with laser beam detectors seek the reflected beam and adjust their flight to hit the spot where the beam is aimed.