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Laser is an electronic device that produces light by amplification of electromagnetic radiation through optical processes. The word laser is an acronym for “light amplification by stimulated emission of radiation”.
- A laser is a device that produces powerful laser light. This device basically stimulates atoms or electrons to emit electromagnetic radiation of a particular wavelength and then amplifies it producing a narrow spectrum of light.
- The branch of optical physics which deals with the study of lasers is called Laser Physics.
- Optical systems and elements used in lasers are called Laser optics.
- Laser light is different from other lights because laser light has identical frequencies and wavelengths in it.
- Amplification of light is achieved in laser due to stimulated emission of radiations.
| Table of Content |
Key terms: Laser, Laser Light, Coherence, Directionality, Monochromatic, Solid-State, Gas, Liquid, Semiconductor Laser
Characteristics Of Laser
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Several distinct features distinguish between normal light and laser light. Some are mentioned below:-
- Coherence- This property states that light receives its emission from the excited electrons that move from higher energy levels to lower energy levels.
- Directionality - The ordinary source of light like electric bulbs or torches receives its mission from the random movement of points. Lasers on the other hand emit light in a very particular direction. This is so unlike ordinary sources which scatter the light in all possible directions.
- Monochromatic- The word monochromatic means a light beam that has a single wavelength. Lasers are monochromatic whereas ordinary light sources contain or range of wavelength energies or colors. That means a white laser that produces white light is not possible.
- High Intensity- The intensity depends on the amount of flow of energy that is through a unit area per unit of time. Ordinary source light spreads out in all directions while laser light is very particular and travels in a particular direction. Because of this, it has a very high intensity.
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Working Of Laser Light [Click Here for Sample Questions]
The output we get from the laser is electromagnetic radiation. In a coherent beam of electromagnetic energy, all the waves have the same frequency and the same phase. The process through which the laser light works is explained here:
- In the first step electric current is supplied so that the lamp is turned on and or off. This results in the excitation of electrons.
- The excited electrons have very high energy and they are returned to their ground state. This leads to the emission of a photon of light
- The emitted photons move in a medium, they bounce off the mirrors. These also excite the other electrons into a higher energy state. This entire process emits more photons by simulating emissions.
- As we can see the number of excited electrons is more than the ground electrons this creates a population inversion.
- Hence, light amplification in laser is due to stimulated emission of radiations.
- Now, the photons are then made to bounce between two mirrors. One of which is less reflective and lets some photons pass through it.
- The photons which can emit through the mirror are then concentrated as a powerful beam of laser light.
Types Of Laser Light
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There are the following four types of laser lights:-
- Solid-State Laser- These are the kinds of lasers that are made up of solid media such as crystalline or Ruby. These are flash tubes that are wrapped up around the laser so that it can excite the electrons. A diode-pumped solid-state laser (DPSS Laser) is a solid-state laser made by pumping a solid gain medium. Neodymium-doped Yttrium Aluminum Garnet laser (Nd YAG laser) is a solid-state laser in which Nd YAG is used as a laser medium.
- Gas Lasers- A gas laser is a laser in which an electric current is sent through a gas to produce light through the population inversion process. Examples of gas lasers include helium-neon lasers, carbon dioxide lasers, argon lasers, krypton lasers, and excimer lasers.
- Liquid Dye Lasers- These are the kinds of lasers that use liquid dyes like road mines in the liquid solution as their medium. In such lasers, the excited electrons are in the form of an arc lamp or a flash lamp, etc.
- Semiconductor Lasers - These types of lasers are very popular and cheap and are called diode lasers because they use a lead to generate the laser pattern. Quantum-cascade lasers (QCLs) are semiconductor lasers that emit in the mid to far-infrared portion of the electromagnetic spectrum. Vertical cavity surface-emitting lasers (VCSELs) are a monolithic type of semiconductor laser with beam emission perpendicular from the top surface.
- Fiber Lasers- A fiber laser is a special type of solid-state laser in which the gain medium is an optical fiber. Fiber lasers are used in a range of applications, including directed energy weapons, material processing, and medicine. Fiber lasers used for these applications include erbium-doped fiber laser and ytterbium laser.
Laser Types by modes of operation
The beam of the laser is either continuous or pulsed, we call this the mode of operation of a laser.
- Continuous wave laser (CW Laser)- A continuous wave laser continuously shoots a single, uninterrupted laser beam. These are commonly used for laser cutting and laser welding.
- Pulsed Laser- In a pulsed laser, the beam is released as pulses that have a specific duration called the pulsed duration. These are commonly used for spot welding and engraving. Pulsed lasers are divided into several types based on the duration of their pulses. Some examples of pulsed lasers based on the pulse duration are milliseconds laser, microseconds laser, nanoseconds laser, picoseconds laser, and femtoseconds laser.
Uses of Laser
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- Carbon dioxide lasers are highly used in industries, they are easy to automate and they don't need sharpening.
- These are highly used in fiber optic cables. And use a technology known as photonics which uses a photon of light to communicate.
- Barcode scanners present in grocery shops or any other store have a printed barcode that uses a laser to convert the barcode into a number that the computer can understand.
- Cool laser is used for skin treatment. It is a non-invasive skin rejuvenation treatment.
- These are used in CD DVD players to convert the pattern of data into numbers and then into music or movies or sound etc.
- These are also used in defense for Guided missiles and weapons.
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Things To Remember
- The word laser is an acronym for “light amplification by stimulated emission of radiation”.
- Laser Physics is the branch of optical physics that deals with the study of lasers.
- Lasers generate coherent, monochromatic light in many wavelengths, both visible and invisible, depending on the type of laser.
- Light amplification in lasers is achieved due to the stimulated emission of radiation.
- Solid-State Lasers, Gas Lasers, Liquid Dye Lasers, Semiconductor Lasers, and Fiber Lasers are the different types of lasers.
Sample Questions
Ques. What is the difference between a flashlight and a laser light? (3 marks)
Ans.
| FLASHLIGHT | LASER LIGHT |
|---|---|
| Produces white light which is composed of a mixture of colors. | Produces a monochromatic light of singular frequency and single color. |
| Spreads into a short fuzzy light | Shoots a narrower and tighter beam over a longer distance |
| Light waves are jumbled. | Light waves are aligned |
| These are non-directional | These are directional |
Ques. What are the correct characteristic properties of laser light? (3 marks)
Ans. The following are the characteristic properties of a laser beam. There are four major categories:-
- Laser beams possess superior monochromatism.
- Laser beams are highly directive.
- Laser beams have the property of showcasing superior coherence.
- Laser beams give high output.
Ques. What is the process which is used to diffuse a laser beam? (2 marks)
Ans. When we want to diffuse a laser beam it should be passed through an Opal glass diffuser or a ground glass diffuser. In simpler ways, the laser beam can also be diffused when it's passed through a white-painted surface. This process makes the laser beam scatter in a wide range of directions.
Ques. What are the important applications of laser light in science and technology? (3 marks)
Ans. Some of the applications of lasers in science and technology are mentioned below:
- Laser beam helps us in the study of the Brownian motion of particles. They also help in counting of the number of atoms present in the substance.
- Laser beam helps us in the study of the nature of the plasma state of the matter.
- Laser beams are also used in astronomy.
- Laser beams help us in the D extraction of information from compact discs or DVDs.
- Lasers also help in the fiber optic communication department.
- These are used in holographs also.
Ques. How is laser light important in the field of medicine? (3 marks)
Ans. A few uses of lasers in the medical field are listed here Fermi Energy
- Treat the varicose veins.
- Helping the improvement of vision during the surgery of the eye on the cornea.
- Help in the removal of kidney stones.
- Help in the removal of the tumor.
- Help with the issue of the prostate.
- These also help to repair the detached retina of the eyes.
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