What is a Laser?

What is a Laser?

One of the first newspaper articles, written about the invention of the Laser, in 1960, said that scientists had invented a death ray. Although it’s true that laser beams can destroy an incoming missile, they can also be used as a medical scalpel, read barcodes at the grocery store or be used to make a laser projector for entertainment.

Lasers are used in thousands of scientific, military, medical, and consumer products for a large variety of applications.

In case you did not already know, the word ” laser ” is an acronym for Light Amplification by Stimulated Emission of Radiation.

The section of a laser that emits radiation consists of a resonant cavity in which the atoms that make up the matter within the cavity (liquid, solid or gas), are stimulated to release photons of light energy.

The resonant cavity is framed by 2 mirrors, one at either end. One mirror is 100% reflective and the other mirror is partially reflective. The lasing medium or matter between the mirrors has to be excited or pumped to cause the atoms within that medium to raise their electrons to a higher state. When an excited atom changes from a high energy state to a low or normal state of excitement it emits a photon of radiation. The photons bounce back and forth between the resonant cavity mirrors and collide with other atoms which further stimulates them to go to an excited state. This process of stimulated emission causes light amplification high enough for some of those photons to pass through the partially reflective mirror.

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The photons escaping from the partially reflective mirror may range from the ultra violet to the far infra-red wavelengths, depending upon the design and lasing power output could also range from nanowatts (optical computer) to Petawatts (Nuclear Fusion experiments). Lasers operate in pulsed or constant wave modes. Pulsed lasers have much higher peak powers than CW or constant wave lasers.

Lasers will continue to develop and provide solutions to problems in all aspects of human life and communications.

Miniaturization of lasers, increased power output and efficiency allow lasers to be used in a large variety of entertainment devices such as Laser Television (including 3D TV), laser holographic projection, microprojectors, professional display and special effects projectors for the public to enjoy.

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