الفهرس 
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Abstract
Laser is an acronym that stands for Light Amplification by Stimulated Emission of Radiation. Laser light has certain properties such as being monochromatic (has a very narrow bandwidth or single wavelength), collimated (has a low divergence angle), and coherent (all the waves are in the same phase of time and space). These properties of laser with different output wavelengths made it of wide use in different fields.A laser consists of the lasing medium, which may be a gas (e.g., CO2), a liquid (e.g., dyes), or a crystal (e.g., ruby), contained in an optical cavity, and a pumping system, provided by external energy. The mirrors at each end ensure that the photons are reflected back parallel to the axis (resonating cavity) in the way that photons stimulate excited atoms for further production of photons. The photons then emerge through the partially reflecting mirror located at one end of the optical cavity.