Laser, History of Laser, Working principle of Laser, Uses of Laser

(Last Updated On: March 28, 2021)

Laser Overview:

Laser lights are highly monochromatic it means the laser beam is made up of a single color or a single wavelength in contrast the ordinary white light from an incandescent light bulb is a combination of many colors or wavelengths and is certainly not monochromatic .The laser is highly coherent means a wavelength of the laser light is in phase in space in time this is because of the orderly electronic transitions that take place in laser. The laser light can travel several hundred kilometers long in space without any destruction. Whereas the corresponding coherence length for wave trains emitted by ordinary light is typically less than a meter. Laser emits light that are highly directional which means the light emitted by the laser are relatively a narrow beam in a specific direction without dispersion. Moreover the laser beam spreads very little and thus can be focused sharply but if you observe the ordinary light bulb it emits light in many directions away from the source.

When man discovered fire till then man knew only the natural sources of light later light source evolved into different artificial forms. Physicists had work to create devices for producing powerful beam of light. This resulted in the invention of lasers. Lasers are an important milestone in the field of engineering in science from a barcode scanner to include detection in high-security areas from a projection pointer to Printers, from optical tweezers for handling delicate matter to cutting off eye strength materials from removing body art or complicated I searchable lasers are simply everywhere lasers have unique characteristics different from ordinary light. This enables to produce highly intense light focus to a small point.

The term laser is an acronym of light amplification by stimulated emission of radiation it is a device which produces an intense beam of monochromatic and coherent light. Invention has some history so indeed lasers.


History of the Laser:

The basic principle of laser is based on the Einstein’s theory of light proposed in 1916 which was later developed by Gordon Gould in 1957. In 1960 Theodore Maiman invented the first working Ruby laser which was also the first optical laser apart from solids such as Ruby researchers have analyzed that some materials like xenon helium or semiconductors can also be used as laser mediums. The Harald laser was based on the theories of Charles Hard Townes and Arthur Leonard Schawlow of 1954. Max Plank 1900’s research paper is also considered as the foundation of the Laser in which he discusses that the light is form of electromagnetic radiation. But the technologies of the laser are evolved in different stages. Different types of lasers have been developed which enhanced the scope of their applications.

Working Principle of the laser:

The working and principle of the laser is based on some important features let us discuss about them. The working principle of lasers is based on spontaneous absorption spontaneous emission stimulated emission and population inversion absorption. An atom consists of different energy states let us consider two different states of an electron such as ground state Eo  and excited state Ex . Electromagnetic energy falls on an atom in the form of photon of frequency f from the principle of conservation of energy the electromagnetic energy is given as the difference of:

hf= Ex– Eo

When the photon energy falls on the electron it jumps from the ground Eo to the excited state by absorbing the energy. This process of absorbing energy from photons is known as absorption of radiation spontaneous emission it is known that electron absorbs energy and moves from lower energy level Eo to the higher energy level Ex but the excited electrons that had jumped to the higher energy state does not remain in the same state for a long period and comes back to its original ground state

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Eo by losing its energy in the form of photons these photons are considered as in coherent light as they do have any correlation in phase thus the electrons in the excited atoms are released on their own from their higher energy state to the ground state emitting photons this is called as spontaneous emission.
The mean life or lifetime of the excited atom is the time for which it stays in that state this is about 10-8 Seconds for spontaneous emission. However the mean life for some excited states is 10 to the power of five times longer and such states are called as metastable state and they play an important role in laser operation.

Stimulated emission:

Stimulated emission in this process the atom is initially present in its excited state Ex. A photon of energy Hf can stimulate the atom to move to its ground state Eo. During this process the atom emits an additional photon with the same energy HF this process is called as stimulated emission as it is triggered by an external photon.

Population inversion:

Population inversion generally in any atomic system the number of atoms in the ground state is more than that in the excited state. This is because of the tendency of electrons to stay in the ground state but in order for more photon to be emitted. There should be more electrons in the excited state this process is achieved through optical pumping and this occurrence is known as population inversion.
The transition electrons do not stay in an excited state for a longer time but in some systems the electrons remain in an excited state for longer period these systems are called as active systems or media. Generally these active systems are compounds or mixtures of different elements. Consider the ecosystem containing a large number of atoms in thermal equilibrium condition at a temperature T before the system is subjected to any radiation there are No number of atoms present in their ground state with energy Eo and a number and Ex in a state of higher energy.
According to Ludwig Boltzmann
Nx= No e(-(Ex– Eo)/T
As the temperature increases due to thermal agitation mode number of atoms move to the higher energy state Ex. Since Ex is greater than Eo the Boltzmann equation requires Nx to be lesser than No means there will be less number of atoms in the excited state compared to the ground state thus only by thermal agitation the populations of Ex can exceed that of Eo. Suppose the atoms are flooded with the photons of energy Ex – Eo then by absorption by ground state atoms. The photons will disappear and atoms move through excited state leading to population inversion thus through stimulated emission of excited state atoms most number of photons will be generated showed that the probability is per attend for absorption and stimulated emission processes are identical. Thus the net if it will be absorption of photons when more atoms are in the ground state when stimulated emission dominates that is when more photons are emitted than the absorbed photons the laser light is produced. The lasers have certain unique characteristics that enable the laser light to be focused hundred times better than the ordinary light. These characteristics are mono chromaticity coherence directionality and sharp focus.

Thus lasers with a unique characteristics illuminate investigate repaired transfer here and we take certainly it is interesting to know about the fundamentals of laser technology as always you could connect it in some form of application in day to day life.
Laser or light amplification by stimulated emission of radiation is a device which produces an intense beam of monochromatic light the working of lasers is based on absorption spontaneous emission stimulated emission and population inversion crystals of lasers are mono chromaticity coherence directionality and sharp focus.


Uses of Lasers:

Photometry:

Laser photometry is basically a method to measure large animals underwater without having to physically take them out of the water or hold a long say rope or measuring device up along the side of them hoping they hold still. This method involves mounting two lasers basically on parallel lines in it involves a lot of precision and a lot of tweaking to make sure these lasers are on precise parallel lines so that the dots would say be maybe one foot apart from each other at all distances or at least within a couple hundred feet you would then aim the two dots at the side of an animal say this whale shark and take a picture of the entire animal with the two dots on it and you can then look at that picture and say these two dots area foot apart how many of those little spacing’s can we fit on this one picture right here and that will give you a pretty accurate size of the length of the animal a lot better than just eye balling it.

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Astronomy:

lasers also have a big place in astronomy the images that you are seeing right here if these yellow lasers coming out of observatories these are sodium lasers which are being used to create guide stars basically doing a reverse distorting of the atmosphere. So they can get a clearer picture of beyond our atmosphere however the process is a lot more complex than that short little summary I just gave you. Lasers are also used on the satellites that scan Mars and the topographical maps. They create if Mars lasers are used on board those satellites and we obviously also use lasers for stargazing and for pointing out different constellations in the sky.

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Level tool:

This type of construction tools will allow you to generate laser lines on walls or surfaces to create a more accurate level get perfect 90-degree angles and other construction purposes with absolutely perfect lines that you wouldn’t otherwise be able to get use.

Medical field:

Lasers are used for a wide variety of things including medical surgery dentistry. They are widely used in tattoo removal. You see them used a lot in MRIs different types of scanners and they are also widely used in skin care. Lasers of different wavelengths have a lot of uses in the medical field.


Fiber optic cables:

Imagine you have a cable a wire that is hollow inside and all the walls on the inside are very reflective like a mirror if you were to shoot a laser in to this wire the laser beam would just keep bouncing off the inner walls of the wire and it would come out the other side. It would not just stop at inside of the laser. If there was a turn it would just keep bouncing and following the wire until it came out the other side and we are using these laser lights to send information and communicate and that communication is now being sent at the speed of light much faster than previous ways of transferring data. Now it’s obviously a lot more complex than that but that’s just a very simplified version.

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Laser Tag:

This one’s pretty simple and straight forward I’m sure most of you have played it in the past just involves using lasers to shoot at targets on your enemies. Usually they will be wearing some type of a vest with the target on the shoulders back and chest if you hit those little targets the enemy will be disabled for a couple of seconds.

Material processing:

This is just kind of a blanket term I use for the different uses of manipulating material with lasers. This can be engraving this can be lasers used for drilling cutting items like metal. The lasers are also used for removing rust and they are also lasers used for welding now. The lasers used for all of these uses are typically in the invisible spectrums and also very high-powered and would burn your skin immediately.

Military:

The military has actually for some time been working lasers into their weaponry using laser systems to shoot down drones, planes and missiles. They have begun mounting them on ships, trucks and on planes. These lasers are also very high-powered and have the ability to go straight through metal.



Disc Drive:

The use of laser diodes in disk drives to read DVDs and CDs inside of your DVD player or your Xbox or whatever it might be inside of any of those devices that take discs there will be a little diode with a little laser that is being used to read that disk.

Agriculture:

The use of lasers as a bird repellent or deterrent now farmers have been installing these type of automatic laser systems on their crops and birds will actually view that laser beam in that laser dot is like a solid rot coming towards them or a stick coming towards them they would not be able to identify that it’s just light and it will immediately scare them away.

Barcode Scanner:

Barcode scanners actually have a laser inside of them that’s producing the moving light that you see going over the barcode. So basically the barcode scanner has a illuminator in it which in this case would be the laser. It sends out the light at that barcode and then some of that light reflects off of those little black lines and that goes back into the scanner and the scanner has a sensor that then decodes it and tells the scanner what the barcode actually said.


Laser Printer:

Laser printer and inside of these type of printers the computer board will come up with whatever the image is supposed to look like whether it be text or a picture it will tell the laser inside what that image is supposed to look like and the laser will trace it out onto a drum inside the printer and that will build up static electricity on the drum the static electricity will then attract onto the page the toner and the fuser unit will bomb the toner to the paper.

 

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About the Author: Engr Fahad

My name is Shahzada Fahad and I am an Electrical Engineer. I have been doing Job in UAE as a site engineer in an Electrical Construction Company. Currently, I am running my own YouTube channel "Electronic Clinic", and managing this Website. My Hobbies are * Watching Movies * Music * Martial Arts * Photography * Travelling * Make Sketches and so on...

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