L.A.S.E.R. Technology and its Applications Research (Term Paper Sample)

LASER Technology
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LASER Technology
Introduction
LASER is an abbreviation Light Amplification by Stimulated Emission of Radiation, which is normally used to describe the laser operation theory. A scientist by the name Albert Einstein first published the concept of laser technology in the year 1917. The first operational laser was constructed in the 1960 by another scientist known as Theodore Maiman in California. He used a ruby crystal to produce laser light. The laser device produces a beam of light, normally in a specific wavelength in the ultraviolet, visible or infrared regions of or ultraviolet in the electromagnetic spectrum. The laser technology was further developed, leading to its wide application in the various fields.
Properties of laser light
As opposed to other forms of light, laser possesses certain special properties that make it considerably more dangerous and effective than the ordinary light of the wavelength. The laser photons have three distinct properties. These include:
1 Coherent- Laser particles are normally in phase.
2 Monochromatic- The laser light are normally of the same wavelength and color.
3 Collimated- The laser particles almost aligned ( parallel), with very little divergence from the origin
Components of a Laser
There three primary components that make up a laser. These include:
1 A gain medium or lasing medium
This part may be a liquid, e.g., an organic solvent or a dye; a gas, e.g., carbon (IV) oxide or helium; a solid, e.g., glasses or crystals; or a semiconductor.
2 A pump or an energy source
This section may be a chemical reaction, high voltage discharge, flash lamp, diode, or another laser.
3 A cavity or optical resonator
This part consists of a void containing a lasing medium. It normally has two parallel mirrors on both sides. One mirror of the mirrors is highly reflective while the other mirror is partially reflective. This allows some amount of light to leave the resonator so as to produce the output beam of the laser. This is known as the output coupler.
The laser is normally named in consideration to the lasing medium. The lasing medium also dictates the type of energy source to be used, and the laser wavelength produced. Figure 1 in the next page shows the various parts of below shows parts of a laser device.
Figure 1: Components of a laser device
Principle of Operation at the Atomic Level
The laser is a very powerful light source, having unique properties, which are not found in the conventional sources of light such as mercury lamps, the tungsten lamp, et cetera. The extraordinary properties of a laser device are that its light waves can travel up to a very long distance with little or no divergence. In cases of traditional sources of light, the emission of light is in a jumble of separate waves that randomly cancels one another, hence travel only up to a very short distance. An analogy of the scenario is a situation where a huge number of pebbles are simultaneously thrown into a pool of water. Each pebble will generate its own wave. Given that the pebbles are randomly thrown, the generated waves by the pebbles will cancel each other. The result of this is that the waves travel only a short distance. If the pebbles are thrown one after the other into the same pool and also at constant time intervals, the waves generate will tend to strengthen one another, thus travelling long distances. In this event, the generated w the waves are said to travel coherently. In a laser, the light waves are exactly in step with eaves are said to be coherent, thus having a constant phase relationship.
It is due to this coherency that makes the laser beam so powerful, so narrow, and easier to be focused onto an object. The ordinary and laser light sources are as shown in figure 2.
Figure 2: Ordinary and laser source of light
Working Principle of laser
Laser Action and Quantum Theory
The action of laser is normally based on well-established concepts of the quantum theory. Mr. Albert Einstein, the greatest scientist, articulated that an excited molecule or an atom, when properly stimulated by an electromagnetic light (wave), would emit packets of light known as photons, having wavelengths similar to the stimulating electromagnetic wave. A scientist by the name Charles Townes was the first is to make use of the process of stimulated emission as an amplifier by manufacturing the very first MASTER. (MASTER is an abbreviation for Microwave Amplification by Stimulated Emission of Radiation. The very first MASTER was made in ammonia vapor. The wavelength of the ammonia vapor used was 1.25 cm. Through extending the principle of MASTER to the optical wavelengths, Charles along with another scientist called Arthur Leonard Schawlow further developed the concept by using an optical mirror cavity and laser amplifier to provide multiple reflections.This is necessary for the speedy growth of light signal into a powerful visible beam. The figure 3 shows the principle of laser action.
Figure 3: Principle of laser action.
Applications of the Laser Technology
Laser technology has found applications in a wide range of fields. Some of the applications are discussed below.
1 Laser Printing
In the last few decades, there has been a significant increase in the application of computers in data processing, management, and dissemination. The application of computers in insurance, bank statements, publicity brochures for advertisements, electricity and telephone bills. The peripheral device needed by the computer to perform all these functions is the printer.
Today, the application of computers in huge data processing installations has placed a very high demand on the printers in regards to its characteristic flexibility, printing quality and the speed. The traditional impact printers no longer meet the ever growing demand due their limited characteristic flexibility and speed. In modern printers, the printing technique is based on the principle of electrophotography. Given that the light source in these printers is laser, they are referred to as laser printers..
Figure 4: Schematic diagram of a laser printer
The photo-conductor drum (1) situated at the centre normally rotates at a constant angular velocity. Its surface is regularly treated with a photo-conductive coating material such as hydrogenated-amorphous silicon. When in the dark, this photo-conductor has a high electrical resistances, which normally drop when the coating is exposed to light. The surface of the photo-conductor is charged electrically by the use of the charge coronation (2). The charged layer is rotated past the write-exposure station, part (3). Only the locations on the surface of the drum where the information is to be printed are exposed.
2 Seismography
In seismographic application, such as underground nuc...