Laser Fundamentals
History: Laser stands for Light Amplification by Stimulated Emission of Radiation. Albert Einstein (1916) theoretically proved the process of stimulated emission (that is, when more atoms occupy a higher energy state than a lower one, it is possible to force them to return to an unexcited state by stimulating them with the same energy as would be emitted naturally). German Physicist Rudolf Walther Ladenburg observed the stimulated emission in 1928. In 1951, Charles H.Townes from Columbia University demonstrated a working device that focused excited ammonia molecules in a resonant microwave cavity, where they emitted a pure microwave frequency. Townes named the device a MASER for Microwave Amplification by Stimulated Emission of Radiation. On May 16, 1960, Theodore H. Maiman (Hughes Research Laboratories) fired bright pulses from a photographer’s flash lamp to excite chromium atoms in a crystal of synthetic ruby and produced red pulses from a Ruby rod about the size of a fingertip. In