LASERS+(Eric,+Sabiha+and+Beth)



"The laser is one of the great technological developments of this century." ~John Whinnery =toc Quantum Mechanics  =

 Quantum Mechanics is very useful in today's society; it helps predict the multiple behaviors of microscopic particles. 11 Quantum Mechanics was created as an alternative reason for unexplained phenomenon that occurred within the scientific world. In the beginning of the 20th century, experiments were done that produced results that could not be explained by traditional physics, the physics of Galileo, Newton, and many other physicists. For example, it was known that electrons orbited around an atom in a pattern similar to that of planets orbiting the sun. Traditional physics stated that electrons would spin out of control and collide with the nucleus. This is proven to obviously not occur, and the only other explanation is that quantum mechanics must explain how the electrons stay in their own respective orbits around the nucleus of an atom. Overall, Quantum Mechanics explains the many mysteries and questions associated with science, those that traditional, classic science is unable to answer. 12

=History of the LASER =

The LASER, standing for **L **ight **A **mplification by **S **timulated **E **<span style="font-family: 'Comic Sans MS',cursive; font-size: 110%;">mission of **<span style="font-family: 'Comic Sans MS',cursive; font-size: 110%;">R **<span style="font-family: 'Comic Sans MS',cursive; font-size: 110%;">adiation, was based off of the invention of the MASER ( **<span style="font-family: 'Comic Sans MS',cursive; font-size: 110%;">M **<span style="font-family: 'Comic Sans MS',cursive; font-size: 110%;">icrowave **<span style="font-family: 'Comic Sans MS',cursive; font-size: 110%;">A **<span style="font-family: 'Comic Sans MS',cursive; font-size: 110%;">mplification by **<span style="font-family: 'Comic Sans MS',cursive; font-size: 110%;">S **<span style="font-family: 'Comic Sans MS',cursive; font-size: 110%;">timulated **<span style="font-family: 'Comic Sans MS',cursive; font-size: 110%;">E **<span style="font-family: 'Comic Sans MS',cursive; font-size: 110%;">mission of **<span style="font-family: 'Comic Sans MS',cursive; font-size: 110%;">R **<span style="font-family: 'Comic Sans MS',cursive; font-size: 110%;">adiation), invented in 1954 by Charles Townes, Arthur Schawlow, and James P. Gordon. The Maser used ammonia gas and microwave radiation as does the lasertoday. The only difference is that there was no visible light used with the Maser. 2 In 1954, Townes and Gordon successfully operated the first Maser with a wavelength of 1.25 cm. The idea of the Maser immediately became popular throughout the scientific community. Scientists started debating whether it was possible to use the same idea of the Maser but instead "gerenate coherent radiation at millimeter, submillimeter and even infrared wavelengths" which led to the creation of the laser(Bromberg 26). The first type of LASER was invented on May 16th 1960 by Theodore Maiman, called the Ruby laser which was the first successful laser using visible light. 2 He successfully shone a high-powered flash lamp on a ruby rod with a surface coated in silver. Maiman tried to publish his findings in many journals such as the //Physical Review Letters//, where he was turned away. He then sent his findings to the journal //Nature// where it was then published. Then, in July of 1960, a public announcement was made to publicize the newfound laser. This was the cause of a great stir in society; people were imagining the worst of what could happen when lasers were implemented into society (death rays) and scientists were skeptical. <span style="color: black; font-family: 'Comic Sans MS'; font-size: 11pt; mso-ansi-language: EN-US; mso-bidi-font-family: Arial; mso-bidi-language: AR-SA; mso-fareast-font-family: 'Times New Roman'; mso-fareast-language: EN-US;">Thomas Maiman used pieces that are not found in more modern lasers, such as a pulsed light source which was light that lasted for a very short amount of time, to “excite” the ruby. This only produced a short beam of light as opposed to a longer, continuous wave, but this was still more than what other scientists expected to occur. To increase the energy of the light produced from the laser, a technique known as “Q switching” was created. This shortened the pulse of the light from the laser which in turn created power of as much as a million billion watts. 4



=<span style="font-family: 'Comic Sans MS',cursive;">The Evolution of the LASER-Different Types of LASERs =

<span style="font-family: 'Comic Sans MS',cursive;"><span style="font-family: 'Comic Sans MS',cursive; font-size: 110%;">1960:Ruby LASER-Theodore Maiman 1960:Gas LASER-Ali Javan-first continuous-light laser 1962:Semiconductor Injection LASER-Robert Hall-used in every day electronic appliances and communication systems 1964:Carbon Dioxide LASER <span style="font-family: 'Comic Sans MS',cursive; font-size: 110%; text-decoration: none;">-Kumar Patel 2

=<span style="font-family: 'Comic Sans MS',cursive;">The Mechanics Behind a LASER-How It Works =

<span style="font-family: 'Comic Sans MS',cursive;"><span style="font-family: 'Comic Sans MS',cursive; font-size: 110%;">Laser, as said above, stands for **<span style="font-family: 'Comic Sans MS',cursive; font-size: 110%;">Light Amplification by Stimulated Emission of Radiation **<span style="font-family: 'Comic Sans MS',cursive; font-size: 110%;">. The first part, 'Light Amplification,' refers to the beam of light that we see. The second part, 'Stimulated Emission of Radiation,' is a bit more confusing. Radiation doesn't refer to radioactive particles as one might think. It instead refers to a radiant vibration. Radiant Vibration, in other words, means that the emissions of lasers is light that can cover frequencies that range anywhere from infra-red to ultraviolet. How does this light appear, though? Something must be happening in the laser to make it happen. That is where Stimulation comes into the picture. Many of the modern lasers we use are called ion gas lasers. This is because inside the laser, there is a gas, or a mixture of gases, as medium. These gases are used because they are easily made to produce visible light. The way that these gases make light is by having electricity run through them. Electricity runs through the gas or mixture of gases produces light, but what happens to make it produce light? That is a little bit more complicated. As the electricity runs through the gas, it "excites" the electrons in the gas and causes them to jump to higher energy levels. The electrons don't stay at the high energy levels for long, and they soon drop back to their ground state. As they drop down, some form of energy must come out because electricity went in to make them go up. The energy that comes out is a packet called a photon or light. With many of these electrons falling back to their ground state, a lot of light is produced. Once an electron is back at its proper orbital, the process can start all over again. <span style="font-family: 'Comic Sans MS',cursive; font-size: 110%;"> With all the light coming off of the electrons, the light travels in many different directions. So how is it that there is a focused beam of light? Well, at the back of the laser, there is a 100% reflective mirror and at the front there is a slightly transparent mirror to let light through. When one photon of light is travelling perpendicular to the mirrors, it will bounce off, and inevitably hit another photon, causing the second photon to take the first photon's trajectory. This reaction will multiply until every photon is travelling in the same direction up the laser. The mirror at the front of the laser is slightly less than 100% transparent (about 95%) so that some light will travel through the mirror and out of the laser to create the very narrow beam of light that we call laser light. The diagram to the right is a very good representation of how this process works. 8 = = =<span style="font-family: 'Comic Sans MS',cursive;">What LASERs Are Used For =

<span style="font-family: 'Comic Sans MS',cursive;"><span style="font-family: 'Comic Sans MS',cursive; font-size: 110%;">The laser has a variety of uses in our every day lives, from cutting, drilling, measuring, DVD and CD scanners, making clothing and helping doctors perform surgery. Depending on the intensity of the laser and the distance between the laser and the project, it can be used for different reasons. For example, a more intense laser may be necessary for laser eye surgery as opposed to a laser used to read a CD. However intense the light of the laser, they play a major role in today's society.

In the medical world, lasers are extremely important. As mentioned before, lasers are used in Laser Eye Surgery so that the doctor can work on the delicate eye without destroying it. Lasers can help treat the far-sighted and those with cataracts, as its small and intense focus of light can correct the damaged tissue. The laser is extremely useful in Laser Ulcer Removal. It is able to make an incision so that a doctor can reach the stomach. Lasers are also effective in removing Port Wine Stains, which is when an accumulation of red blood cells under the skin results in red marks. Laser surgery removes the marks and does not hurt the outer skin or the blood cells around the damaged area. 6

As technology begins to grow, so does the use of the laser. CD players use a laser to read the CD that the user puts inside. The laser translates the codes on the CD into music. Supermarket scanners are also a good example; the item's bar code is scanned by a laser, which translates the items' code into information about the item itself. 6

Lasers are often used in light shows as entertainment. Lasers of different sizes, types and colors are used, and the combination of lights is beautiful and artistic, and is a form of entertainment for many. Class 1 type of laser is used for laser shows, since this type of laser does not harm on contact. <span style="font-family: 'Comic Sans MS',cursive;"> 6

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<span style="font-family: 'Comic Sans MS',cursive;"> NASA, National Aeronautics and Space Administration, has a large use for lasers in its technology. LISA, Laser Interferometer Space Antenna, is an example of one of NASA's use of lasers. It is a space-based gravitational wave detector, and measures the changes of the separation between three spacecrafts, each five million kilometers apart. 7<span class="wiki_link_ext"> With this device, NASA will be able to find more information about the formation and growth of black holes, stars, and the structure of our Galaxy.

NASA uses laser technology to determine information about the Earth as well as space. Many different aspects of Earth's atmosphere is monitored and measured. Water vapor and the density of aerosols in the atmosphere are measured, as well as cloud-cover and pollutants.10 The following diagram shows an example of the use of lasers in the sensing of winds from space:



The laser is used in many ways that many do not expect, and is used in our everyday lives even without our recognizing it.

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<span style="color: #000080; display: block; font-family: 'Comic Sans MS',cursive; font-size: 160%; text-align: center;">"Okay, no problem. Here's my second plan. Back in the 60's, I had a weather changing machine that was, in essence, a sophisticated heat beam which we called a 'laser.' Using these 'lasers,' we punch a hole in the protective layer around the Earth, which we scientists call the 'Ozone Layer.' Slowly but surely, ultraviolet rays would pour in, increasing the risk of skin cancer. That is unless the world pays us a hefty ransom." ~Dr. Evil

** by Sabiha Madraswalla, Beth Noble, and Eric Tyler ** = = =<span style="font-family: 'Comic Sans MS',cursive;">Sources =

<span style="display: block; font-family: 'Times New Roman',Times; font-size: 16px; line-height: 32px; text-align: left;">Works Cited 1. Bellis, Mary. "How a Laser Works." Inventors. Web. 01 Jan. 2010. 2. Bellis, Mary. "Lasers - The History of Lasers." Inventors. Web. 31 Dec. 2009. 3. Bromberg, Joan L. "The Birth of the Laser." //Physics today// Oct. 1988: 26-33. Print. 4. Garwin, Laura, and Tim Lincoln. "The first laser." University of Chicago Press, Books. University of Chicago, 2003. Web. 09 Jan. 2010. 5. "Invention of the Maser and Laser." Physical Review Focus. 27 Jan. 2005. Web. 31 Dec. 2009. 6. Jezek, Geno. "Applications And Uses Of Lasers." How Lasers Work. 2006. Web. 08 Jan. 2010. // 7. LISA: Laser Interferometer Space Antenna Project. NASA, 6 Aug. 2009. Web. 09 Jan. 2010. // 8. Mueller, Bob. "Laser Show Basics/how a laser works." ILDA - The International Laser Display Association. The Laserist. Web. 06 Jan. 2010. 9. Muncheryan, Hrand M. //Principles & Practice of Laser Technology//. 1st ed. United States, 1983. Print. 10. "NASA - Laser Technology: Shedding Some Light." NASA - Home. NASA, Dec. 1996. Web. 08 Jan. 2010. 11. "Quantum Mechanics." Stanford Encyclopedia of Philosophy. Stanford, 29 Nov. 2000. Web. 7 Jan. 2010. 12. Stedl, Todd. "Todd's Quantum Intro." Todd's Quantum Intro. July 2005. Web. 07 Jan. 2010.