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Rahul Singhmar
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Laser
“Laser” is an acronym for Light Amplification by Stimulated Emission of Radiation.
Basic principle of laser
Basic Principles of Lasers is to explain the process of light amplification in a laser requires an understanding of the energy transition phenomena in the atoms of its active medium. They include: spontaneous emission, stimulated emission/absorption and non-radiative decay.
How laser works?
A laser is effectively a machine that makes billions of atoms pump out trillions of photons all at once so they line up to form a really concentrated light beam.
A red laser contains a long crystal made of ruby with a flash tube surrounding it. The flash tube is similar to a fluorescent strip light, only it's coiled around the ruby crystal and it flashes every so often like a camera's flash.
About
A laser is a device that emits light through a process of optical amplification based on the stimulated emission of electromagnetic radiation. The term "laser" originated as an acronym for "light amplification by stimulated emission of radiation"Formation of laser
A laser is created when the electrons in atoms in special glasses, crystals, or gases absorb energy from an electrical current or another laser and become “excited.” The excited electrons move from a lower-energy orbit to a higher-energy orbit around the atom's nucleus.
Working of laser
A laser is created when the electrons in atoms in special glasses, crystals, or gases absorb energy from an electrical current or another laser and become “excited.” The excited electrons move
from a lower-energy orbit to a higher-energy orbit around the atom's nucleus.
Laser made up of
They're powerful beams of electromagnetic radiation. Laser beams can be made from visible light, x-rays, ultraviolet light or infrared light.
Applications
Laser technology must have a various application fields, in almost any of the science field you may observe laser technology applications and devices. In the following I mention the applications of such technology as far as I encountered, observed, used, or read about:
Computer devices such as laser mouse, laser presentation, CD ROMs and DVD ROMs
Astronomy and communication applications
Medicine, surgery, and health
War machines, guns and tanks
Cutting matters in metallurgy industry and related industries
Robotics, especially in image processing and calculating distances
Toys
Types of Laser
Lasers are classified into 4 types based on the type of laser medium used:
Solid-state laser.
Gas laser.
Liquid laser.
Semiconductor laser.
Some special Lasers are
Helium Neon Laser and Ruby Laser
1. Helium Neon Laser:
The first system was the helium neon (HeNe) gas mixture. Although its first successful operation was at an infrared wavelength of 1.15 µm, the HeNe laser is most well known operating at the red 633 nm transition. Some HeNe lasers today also can emit operate at other wavelengths (594 nm, 612 nm, 543 nm). Some earlier HeNe lasers were excited by radio frequency (RF) discharge but virtually all HeNe lasers today are driven by a small DC discharge between electrodes in the laser tube.
Operation
The HeNe laser operates by an excitation of the helium atoms from the ground state. This energy excess is coupled to an unexcited neon atom by a collisional process with the net result of an inversion in the neon atom population, thus allowing laser action to begin. Power levels available from the HeNe laser ranges from a fraction of a milliwatt to about 75 milliwatts in the largest available systems. The HeNe laser is noted for its high-frequency stability and TEM(oo) (single mode) operation. The HeNe laser is one of the most widely used laser in existence today. Its pencil-thin beam is used in surveying work, to align pipelines, as a sawing guide in sawmills, and is also used to “align” patients in medical X-ray units, just to name a few of its many applications. It is also used in many retail scanners, lecture hall pointers and display devices. In addition, holograms are often made using the coherent light of HeNe lasers.Ruby laser
A ruby laser is a solid-state laser that uses the synthetic ruby crystal as its laser medium. Ruby laser is the first successful laser developed by Maiman in 1960.
Ruby laser is one of the few solid-state lasers that produce visible light. It emits deep red light of wavelength 694.3 nm.
Construction of ruby laser
A ruby laser consists of three important elements: laser medium, the pump source, and the optical resonator.
Laser medium or gain medium in ruby laser
In a ruby laser, a single crystal of ruby (Al2O3 : Cr3+) in the form of cylinder acts as a laser medium or active medium. The laser medium (ruby) in the ruby laser is made of the host of sapphire (Al2O3) which is doped with small amounts of chromium ions (Cr3+). The ruby has good thermal properties.
Pump source or energy source in ruby laser
The pump source is the element of a ruby laser system that provides energy to the laser medium. In a ruby laser, population inversion is required to achieve laser emission. Population inversion is the process of achieving the greater population of higher energy state than the lower energy state. In order to achieve population inversion, we need to supply energy to the laser medium (ruby).
In a ruby laser, we use flashtube as the energy source or pump source. The flashtube supplies energy to the laser medium (ruby). When lower energy state electrons in the laser medium gain sufficient energy from the flashtube, they jump into the higher energy state or excited state.
Optical resonator
The ends of the cylindrical ruby rod are flat and parallel. The cylindrical ruby rod is placed between two mirrors. The optical coating is applied to both the mirrors. The process of depositing thin layers of metals on glass substrates to make mirror surfaces is called silvering. Each mirror is coated or silvered differently.
At one end of the rod, the mirror is fully silvered whereas, at another end, the mirror is partially silvered.
The fully silvered mirror will completely reflect the light whereas the partially silvered mirror will reflect most part of the light but allows a small portion of light through it to produce output laser light.
Working of ruby laser
The ruby laser is a three level solid-state laser. In a ruby laser, optical pumping technique is used to supply energy to the laser medium. Optical pumping is a technique in which light is used as energy source to raise electrons from lower energy level to the higher energy level.
In an active medium (ruby), a process called spontaneous emission produces light. The light produced within the laser medium will bounce back and forth between the two mirrors. This stimulates other electrons to fall into the ground state by releasing light energy. This is called stimulated emission.
What is the difference between he Ne laser and ruby laser?
he-ne laser is gaseous state. Ruby is solid state laser. ... he-ne laser requires electrical pumping. ruby laser requires optical pumping.
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