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| Lasers-An Introduction |
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| The laser is an acronym for Light Amplification by Stimulated Emission of Radiation. The laser has been invented and developed in 1959 and 1960. |
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| In the laser, the maser principle has been extended to optical or visible light frequencies of 1014 to 1015 cycle/s. Laser may be called "optical maser". In the past, light sources of high intensity utilised heated filaments or arcs or an aggregate of tiny light sources operating independently of each other. The emission was a continuous spectrum of incoherent light. The laser provides the first opportunity to generate high intensity coherent or truly monochromatic light; the radiation will produce interference patterns and can be readily focused in a small neighborhood. Lasers can be solid state or discharge tube devices. In 1917, Albert Einstein predicted the possibility of stimulated emission of radiation. This gave the theoretical basis for the development of maser and laser. In 1954, the prediction of Einstein was put to practical use by C.H. Townes and his co-workers. They discovered MASER. |
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| The principle of maser was adopted for the radiations of visible region by A. Schawloo in collaboration with Townes in the year 1958. The first laser device was developed by T .H. Maiman in the year 1960. It was "Fabry Parot Optical cavity resonator" in which ruby crystal was used as an amplifying medium for light. It is often called Ruby Laser. It emits red light of wavelength 694.3 nm. |
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| Javen developed the first gas laser using He and Ne gases. It is called Helium-Neon Laser. It emits visible light at wavelength 632.8 nm and also in infrared region at 1150 nm. ,CO2 laser emits radiation at 10.6 mm wavelength. |
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| Comparison of Ordinary beam of light and Laser beam |
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