Laser
The word stands for Light Amplification of Stimulated Emission of Radiation. Laser gives a narrow, accurate beam of very bright light. Unlike ordinary light, all rays of a beam of laser have the same wavelength and are perfectly in phase and parallel to one another.
According to Quantum Theory, energy is transmitted in packets (Quanta). In laser, the quanta are organized end to end. Thus in vibrating together, they produce light of a very high intensity.
Laser beams can either be visible light or be invisible, in which case they are composed of infrared rays. An infrared laser can cut through substances ranging from metal to human tissues with extremely fine accuracy. Therefore, it has found application in the field of medicine, especially for microsurgery. Visible light lasers are also used in recording, CD Rom players and fiber-optic communications.
A laser beam is produced by exciting atoms of a medium that can both absorb and release energy. There are a variety of substances that can work as a medium, such as ruby, some liquid dyes or a gas like carbon dioxide.
Charles H Townes, an American physicist, discovered laser in the early 1950s. He and his students constructed the first maser and showed that a similar device producing a visible light (laser) was also possible. For his invention of maser and later laser, he shared the 1964 Nobel Prize with Aleksandr M Prokhorov and Nikolay G.Basov. Based on Charles H Townes’ earlier work, Theodore Maiman constructed the first laser in 1960, using a rod of ruby.
* Before the laser was developed, there was the“maser” . This stood for “microwave amplification by stimulated emission of radiation” and was based on Albert Einstein’s principle of stimulated emission masers, which were used in atomic clocks.
* The light in a laser is more parallel than any other light source; every part of the beam has almost the exact direction.
* In 1974 lasers were used commercially for the first time in supermarket bar code scanners.
