When do you use laser beams?

Answer 1

Laser light is used whenever it is important that all of the light rays are in phase with each other (when the beam is coherent)

Coherence in a light beam helps it travel large distances without spreading significantly. Thus, it is used for laser pointers, so you can point across the room and still make a 3mm dot on the wall.

Coherence in the beam also allows information to be retrieved by interferometry. Splitting the laser beam, sending one half to a target and letting the other go straight, then recombining the two can give extremely accurate measurements of distance from the receiver to the target.

A variation of this procedure is used to produce holograms.

Answer:Lasers are often used in communications since it is possible to send a signal through many miles of glass fiber (over 180 miles) without having signal amplifiers or repeaters. Lasers can also send signals through the air or through space but this is not generally used since laser beams travel in straight lines and cannot follow the curvature of the earth without using a glass fiber. It is also difficult to aim a communications laser accurately at a distant moving target while radio waves illuminate a much larger area.

Lasers are also used for cutting, drilling etching and otherwise processing a wide variety of materials including metals and plastics. Lasers can be focused to very fine points allowing small holes or cuts to be made in nearly any material. Lasers are also used in medicine to remove tissue (laser eye surgery) and destroy tattoos or skin blemishes.

As mentioned above lasers can be used to precisely measure long distances by splitting the beam and bouncing one portion off a reflector on a distant target then comparing the phase of the returning beam to the reference beam. Interferometry is so successful that the definition of the fundamental distance unit, the meter, is given as wavelengths of light instead of he distance between scratches on a metal bar.

Lasers are used by the military to designate spots where a missile can home in to destroy a target or to help aim small arms using laser dot sights. Laser range finding is used to target tank fire as well. Several laser systems are being developed to shoot down missiles, mortar and artillery rounds and working prototypes of some systems exist. However as of 2010 there are no fielded laser weapons that use the laser beam itself to destroy a target.

Lasers are also key to information storage in the form of CD, DVD and Bluray technology. The ability to sharply focus the laser is used to read and write small dots on a spinning disc of plastic with metal foil layers.

Lasers are also used for performance and entertainment (laser pointers and laser light shows)

To summarize lasers are commonly used for communications, data storage, measurement, weapons targeting, machining operations, medical applications and entertainment.