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vietnam war memorial
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Table of Contents Picture Of Laser Title Page Problem Statement Problems Encountered Problem Solutions History of Lasers Practical Uses of Lasers Medical Uses of Lasers Possible Future Uses of Lasers and Laser Types Bill Phillips, Albert Einstein and Others Pictures Sketches Final Drawing Bibliography Problem Statement To design and construct a project that turns on or off an electrical device, after being reflected three times in a given area by a laser beam. Problems Encountered The only problem we encountered during our project was after we had painted our Project. The cardboard started to bend in toward the middle and the laser beam would not reflect into the correct spot. Problem Solutions To counteract the cardboard from bending, we stabilized the cardboard by using the hot glue gun and connected the pieces or cardboard together tightly. History of Lasers Laser is the acronym of Light Amplification by Stimulated Emission of Radiation. Laser is light of special properties, light is electromagnetic wave in visible range. It is a long history for human beings to realize that light is both wavelike and particle like. In 1704, Newton characterized light as a stream of particles. The Young’s interference experiment in 1803 and the discovery of the polarity of light convinced scientists of that time that light is wave. Maxwell’s electromagnetic theory explained light as rapid vibrations of EM field due to the oscillation of charged particles. At the turn of the 20th century, the black body radiation phenomena challenged the wavelike light theory. According to Maxwell’s EM theory, the energy intensity of EM emissions with frequency f is proportional to the square of this frequency, integrate the intensity from zero to infinity frequencies over the limited black body volume will result in infinite energy, which is of course impossible! It was until Plank introduced the "quantum" concept in 1900 when this was explained. Thus energy is not continuous, it is discrete and can only be the multiples of a small unit. Einstein proposed the concept of "photon", we can say light is composed of individual particles called photons which posses a discrete amount of energy or quanta. Einstein also predicted in 1917 that when there exist the population inversion between the upper and lower energy levels among the atom systems, it was possible to realize amplified stimulated radiation, i.e., laser light. Quantum Mechanics was developed to explain these new phenomena since 1920. Now we think that light is composed of "particles" whose motion probability is determined by its wavelike behavior.
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