What is LASER for BTech 1st Year Physics


It is an acronym for Light Amplification By Stimulated Emission Of Radiation. It is a process by which we get a coherent, highly monochromatic and perfectly parallel beam of light. Lasers may also be called as optical masses. It has been invented and developed in 1959. The laser provides the first opportunity to generate high intensity coherent monochromatic light. In 1917, Albert Einstein predicted the possibility of stimulated emission of radiation, which formed the basis for Masers and Lasers.

            The “L” in the acronym means light.  A laser is a beam of light that uses the force of light and directs this light in one direction.  The “A” in the acronym stands for amplification and just means that you can make the laser an intense beam of light or not as intense beam of light.  The “S” in the acronym is what really starts the process of creating a laser.  One thing you have to realize when creating a laser is that atoms are made up of electrons.  Once these electrons get “stimulated” or excited by an outside source, usually intense flashes of light, they become electrons that are in a higher energy state then they were before emission.


This process is also called getting “pumped,” which just means the medium that the electrons are in are becoming electrons in the excited state.  In the excited state, the electrons release their excess energy by giving off a particle of light or a photon.  Electrons release their excess energy because they like being in the lowest state possible or ground state.  This release of light energy from electrons is called Emission.  The emitted photon of light has a very specific wavelength that depends on the state of the electron’s energy when the photon was released.  Atoms that have the same electrons in identical states will release photons with the same wavelengths.


Finally, mirrors are placed at the ends of the medium being used.  The photons emitted with certain wavelengths reflect off the mirrors and travel back and forth through the medium.  As they do this, the photons stimulate other electrons to emit photons of the same wavelength.  Soon, there are a lot of photons in the medium that all have the same wavelength.  One of the mirrors placed at the ends is not a total reflective mirror.  It reflects most of the light, but some photons get through the mirror.  The light that passes through this mirror is the laser beam and a laser is finally created (Lasers).

laser schéma

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