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people see Lasers When most people see a laser beam they are amazed by its unique physical properties. Laser light is so unique from other light because it is coherent; unlike ordinary light, which travels in all directions, laser light travels in a straight beam. The word laser is an acronym for Light Amplification by Stimulated Emission of Radiation. The history of the laser is very interesting.
Lasers have changed immensely since they were first invented. Before the laser was invented, Charles Townes developed the maser in 1954. The maser has basically the same principles as the laser, but it involves microwaves instead of light. The maser lead Theodore Maximum to assemble the first working laser in 1960; he did this by applying the masers qualities to light. This first solid-state laser was a ruby crystal laser.
A year after the first solid-state laser was invented, the first gas laser was constructed by Ali Javan, W. R. Bennett, and D. R.
Herriot. This was a helium-neon laser. The helium-neon laser is the most common laser found today. Many other types of lasers have been invented since then: the semiconductor laser (1962), the chemical laser (1964), the liquid laser (1966), and the free electron laser (1977). All lasers work basically on the same principles. First the atoms in the substance used are pumped.
For example, the helium and neon would be pumped in a helium-neon laser. This is where the electrons of the atoms jump to higher orbitals, which have more energy. The substance can be pumped by using flash lamps, other lasers, atomic explosions, electric discharges, solar energy, and etc When the atoms are pumped, they perform stimulated emission. This is where the electrons are stimulated by photons to release coherent photons of a single frequency and color.
After the pumping process, the oscillation process takes place. In this process energy is amplified to make it stronger and more useful. This is done by bouncing the photons between two mirrors until they reach a certain intensity. The two mirrors are one of 100 percent efficiency and one of a lesser efficiency. When the photons reach the certain intensity, they leave the mirror of lesser efficiency in a coherent beam. There are basically four main types of lasers: solid-state, gas, liquid, and semi-conductor.
Solid-state lasers are made from a crystalline material such as ruby. The crystals have impurities in them that can be stimulated to release radiation in a coherent fashion. These impurities are needed to make the laser last for long periods of time. If the crystals do not have impurities, then they can have some added; this is called " doping. " The crystals in solid state lasers are usually pumped by using flash lamps. Gas laser beams are much more coherent than the beams of solid-state lasers. Gas lasers are lasers that contain a tube of gas or a mixture of gasses.
The most common gas laser is the helium-neon laser. Unlike solid-state lasers, gas lasers are pumped by using electrical discharges. Liquid lasers are usually filled with an organic dye substance. These lasers allow measurements to be taken on a scale never thought possible. They can do this because they can be flashed in pulses lasting only billionths of a second. Liquid lasers are pumped in a very unique way; they are pumped by using other lasers.
The ruby laser is the most commonly used for this process. The semiconductor laser is the most advanced of the four main types of lasers. These lasers are able to be made smaller than any other type of laser. This is because the semiconducting substance used can be smaller than a grain of salt.
The most common semiconductor used in these lasers is gallium arsenide. This type of laser is the kind that is used for fiber optic communications. Because there are so many types of lasers, they can be used to do a variety of things. One thing they can be used for is the measurement of distance and motion.
Lasers are great for this because their frequencies are very sensitive to motion; they can sense even the smallest of movements. Lasers can be used for measurement by comparing their wavelengths with a specific unit of measurement. There are devices that can measure the number of wavelengths in a desired area, so they can be converted into a different unit. Lasers are great for the measurement of optical components such as lenses and prisms. Lasers are also used a lot in industry. Cutting is one of the applications of lasers in industry.
Laser beams can be focused into a very small spot that is of high power. The laser can then be used to cut materials that are to small, hard, or thick to be cut in any other way; the cuts are also very accurate. Laser are also used in industry during constructions and land surveys. For example, lasers were used in the construction of the Bay Area Transit System; they used them to make precise alignments of materials. Land surveyors use lasers to observe the movements of the fault lines after earthquakes.
Lasers are also used in scientific research. Scientists have used lasers to calculate the speed of light to more accuracy than ever before possible. Lasers are also used in chemistry. For example, individual chemical reactions can be induced without inducing others. Also, lasers can be used to detect and measure things of trace amounts in substances. Communication is another thing that lasers are used for.
Lasers are great for this because they are able to travel large distances without any reduction in quality. This makes lasers great for communications from earth to space during space flights; the atmosphere usually interferes with other forms of communication. Fiber optic cables are used for communications in most everyones telephone calls or computers. These cables are able to trap laser light so it can be directed where ever the cable goes. Lasers are also used in recording sounds and videos. Compact disc players and videodisc player are examples of this.
The medical field also make use of the lasers wide range of capabilities. Laser are mostly used in making precise cuts and holes during surgery. Cancerous tumors can also be removed with the use of lasers. The area of medicine that the laser is used the most in is eye surgery. Lasers are used to reattach retinas, and even to improve vision to make glasses obsolete. Lasers also play a big part in the military.
Lasers can be found on almost all military airplanes and missiles. The laser provide them with the most advanced guidance systems available. Laser may also be used the shoot down missiles that are in danger of hitting critical areas. President Reagan suggested that these lasers be mounted on satellites in space to prevent missile attacks on the United States; this was nicknamed " star wars. " Lasers are also used on some of the militaries guns as advanced aiming devices. As you see, lasers have come along way since the first one was invented.
They come in a variety of different forms. Because of the wide variety of lasers, they can be used for many different functions. They can be used in industry, medicine, communication, science, military, and much more. Lasers have played a big part in todays technology. BIBLOGRAPHY " Laser. " Funk and Wagnalls Encyclopedia. Copyright 1994 by Funk and Wagnalls, Corp.
Maurer, Allan. Lasers: Light Wave of the Future. Arco Publishing. New York, New York. 1982. pp. 1 - 166.
Lengyel, Bela. Introduction to Laser Physics. John Wiley and Sons, Inc. Sydney. 1966. pp. 49 - 289.
Mauldin, John. Light, Lasers, and Optics. Tab Books, Inc. Blue Ridge Summit, PA. 1988. pp. 143 - 158.
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