LASER: The angel you don't know

Many see laser as a word, some see it only as a weapon, few see it as a tool but I tell you what, everyone is correct to some extent. Some see laser as a word cause it sounds better than some words, many who have seen the James bond (007) movie or the Resident evil series will be forgiven when they say laser is only a weapon while very few who have worked in the industrial sector would see laser as a tool.

[free image by US Army]
Apart from the people that see laser as a word, I would say the rest are correct. Laser is an acronym which means Light Amplification by Stimulated Emission of Radiation. Its no suprise laser is some how connected to Einstein since he really studied light and uncovered many mistery about light. The principle of laser is based on his two works, stimulated emission and quantum mechanics. The accronym "laser" took its name from "MASER" which apparently does the same but whereas masers give off radio and microwaves, lasers produced light.

Principle of operation

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For us to understand why laser light are very unique and powerful, lets perform a little experiment. Just fill your bath thub half way or less with water, after this allow the water to settle for some minutes, say 20 minutes. When the water has settled, tap the surface of the water and observe the ripples generated by your hand and watch it propergate to the egdes of the thub back and forth.

This simple act does no harm just like the ordinary light from your torch and many orther normal light sources. But then, begin strocking your hand up and down the thub in a synchronized manner with the water movement, start slowly and increase your speed gradually. A continual movement of your hand in this manner could empty the water in the bath thub on the floor and it is still the same "ordinary" wave you generated when you tapped the surface of the water that was stimulated up to the point of splashing the water on the floor.

Ocean waves are very powerful because of this action that is occuring naturally inside the water. Laser is based on this same principle, stimulated emission. Lasers comes from a light tube which keeps light and stimulate it till it reaches a particular concentration and then shoots off the light. I know many would ask what type of light is used in producing lasers but before that lets get to know "light" better.

Light

Many would say "I know light, I see it everyday". Well that's a bit true cause from a tender age we are able to differentiate the presence of light from its absence, kids tends to cry once there's a lightout. But there's more to light than just "that bright stuff". The only natural source of light we have is the light produced by a fission reaction in the sun and it spends average of 8 minutes before reaching us here on earth surface. Two intelligent physicists have looked at light in two different ways.

[credit: wikimedia]
Newton first examined light and said it was a stream of particles. He was correct in his own term cause light keeps shooting out of its source like bullets would leave a gun in a very great speed. Another intelligent physicist Huygens said this was not correct, that light is a wave. He was also correct in his own term as light exhibits properties of waves in the sense that light could bounce back (reflection) after hitting a surface, change its speed (refraction) as it moves through different media, enlarge after passing through a tiny path (diffraction) and many other properties of wave. Since these two men are correct, then light is both particle and wave hence the expression found in most physics texts, "wave particle paradox".

I'll start by saying that light is an energy and this is a proven fact. According to the law of energy conservation, energy can neither be created nor destroyed but can change from one form to another. If law of conservation of energy is correct and light is not created, where then does light comes from? Light has an atomic history and it doesn't get simpler than that.

Electrons exists inside atoms and they do so in levels (just like our accounts in steemit exists in levels) of energy. These electrons by default exists in these levels with a good stability but once it receives energy, it tends to change its energy level to a high one (just like your SP increases after you claim your reward) but at this energy level, the stability of the atom has been compromized. At the pick of this excitation, the electron will tend to move back to a more stable energy level, in the process of doing this, it gives off photons as a byproduct of its initial movement. This photon is an energy (as already stated) in the form of light.

Ever wondered why some solar panels are not white in color, after all white color might even look like a better variant of the panels in black color? Well the reason is simple, black colors tend to hold back the light rays falling on them and as it absorbs this energy, this is where solar cells comes into play, instead of the absorbed energy going off as photons, it is converted to electric current. Having understood what light is, let us get to know the characteristics of this type of light that is a emitted by lasers.

Characteristics of Laser light

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As stated already, lasers are not just ordinary lights. Three major characteristics makes laser lights what they are and these are, Laser lights are monochromatic, collimated and very coherent.

Monochromatic

The term monochromatic is of Greek origin meaning light of single color. If we are to give this a better scientific definition, then monochromatic lights are lights with single wavelength.

Our natural source of light comes with mixture of many colors, existing at different frequencies. Laser lights are either bright red in color or it is totally invisible though sometimes we have some spotting a very appealing green coloration but whichever color it gives off, the light has a definite frequency and definitely, a single wavelength.

Collimated

A light is said to be collimated if its rays exist in a parallel form. That is to say the rays are not divergent but convergent at infinity. A very good example of light that is not collimated is light from our phones. Their rays scatters as soon as they are outside the source. Laser beams are very powerful partly because their rays are very narrow and maintain the same distance between each other.

Coherent

Looking at light as waves, it maintains many cycles consisting of successive crests and troughs. The crest of a wave is the peak value or the maximum upward displacement found in the cycle of a wave. The light reaching us naturally or even the lights from our torchlights have an unordered wave partern. Sometimes in the wave partern of a naturally occuring lights, we have the trough of a beam interfacing with the crest of another beam. But this is not the same with laser light, Their wave forms are orderly, think of this as the difference between the movement of people in the market place and the movement of soldiers in the parade ground.

Applications of Lasers

As already stated, lasers are angels we don’t know. They are around us in fact an average person uses laser more than twice a day. Starting from a very simple application, lasers are found our computer compact disc read only memory (CD-ROM) player.

The information encoded on the CD plates are decoded by our computers by bouncing back laser lights on the optical reader from the patterns on the disc. Since lasers are very precise, the patterns can be decoded and reassembled appropriately.

Lasers are also widely deployed in the communication industry. With the increase in the demand for faster internet connections, fiber connections are also increasingly becoming the only option for data transfer. As we all know, fiber cables transmit information using lights and which other light source is precise enough to travel that unending tube other than lasers? They are also used in supermarkets and malls for reading barcodes.

[credit: wikimedia]
Ever wondered why barcode reader never make mistakes? Well, lasers are used in transforming lights bouncing back from those linear lines into codes the computer can easily and quickly translate into an item, hence anytime you visit the grocery store and the barcode scanner was used in reading the amount of items you bought, then have it at the back of your mind that you just used a laser technology.

I am sure most of us are very conversant with the movie “Die Another Day” by the star actor James bond. He used a wide range of technology in the movie and among those technologies was his laser powered wrist watch which he used to cut into ice and it was always handy. Lasers can be used to make very precise cuts especially in the fabrics industry. They are also used in the military for guiding missiles. Heard about the Strategic Defense Initiative?

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Reference

1. Laser -wikipedia
2. lasers -explainthatstuff
3. how lasers works -lawrece livemore national library
4. wave particle duality -wikipedia

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