Gagne de la cryptomonnaie GRATUITE en 5 clics et aide institut numérique à propager la connaissance universitaire >> CLIQUEZ ICI <<

3) The laser

Non classé

In 1917, Albert Einstein was the first to theorize the physical principle leading to the discovery of the laser. According to him, a material can emit light when it is properly excited, so it is possible to stimulate the emission of electromagnetic radiation by matter by exciting the electrons of the atoms that compose it. Skepticism facing many of these fellows at the time, it will take 35 years before the theory becomes reality.

The word LASER stands for “Light Amplification by Stimulating Emission of Radiation”. This amplification produces a coherent light beam that is to say whose wavelength is uniform and that the particles move in the same direction.

The first laser was created in 1960, in response to huge quantities of applications in all areas. Charles Townes, a young American, manufactures already in 1953 the forerunner of what we know today of the laser, he called the MASER (Microwave Amplification by Stimulated of Radiation). However the first LASER is manufactured by Theodore Maiman.

The laser

Masers were used for the transatlantic broadcast a television for example. But the technology required too much stress; it was strong magnetic fields and cooling system very complex.

Photo by Bettman

A hydrogen radio frequency discharge, the first element inside a hydrogen maser ->

A hydrogen radio frequency discharge

Page suivante : 4) Holograms

Retour au menu : Hologram : A niche market