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The Laser

Definition :

The term “Laser” means Light Amplification by the Stimulated Emission of Radiation. This device creates a uniform and coherent light (different from an ordinary light bulb).

The process is based on an optical amplification, by stimulating the emission of photons.

Many lasers are able to deliver a light where the beam is parallel and approaching a single wavelength and thus very pure.

Formula :

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Schematic: Image Added

How it work ?

A laser is an optical oscillator, which is can be made out of a solid, liquid or gas. It contains two with mirrors at both ends: one is totally reflecting and the other only partially. To make it work, the material is excited or "pumped," with an energy source such as light or electricity.

When this energy source gives energy the electrons in the atoms, they become excited. But the interesting part is when a few of the electrons drop back to lower energy levels spontaneously, and then release a photon (or a quantum of light). The photons created stimulate other excited electrons and emit more and more photons. Then the light waves (photons), which passes through the laser medium, is reflected by the mirrors at both ends. It keeps the light back and forth creating a chain reaction. After that the light beam goes out through the output.

Uses :

The laser is part of our daily life. Many examples…

The laser pointer used in classrooms
The CD in a computer or in a hi-fi that are used to read the data stored in a CD.
In industry, laser is often used for cutting and microscopic processing.
For military purposes, laser is used to intercept guided missiles.
Scientists have also accurately measured the distance between the Earth and the Moon by using laser