LASER(Light Amplification by Stimulated Emission of Radiation) A laser is a very special source of light and it generates optical radiation utilizing a process called stimulated emission. The basic principles of stimulated emission process were enunciated by Albert Einstein as early as 1917. The first laser system was designed and fabricated by Theodore Maiman in the Hughes Research Laboratories, USA in 1960. This heralded a major revolution in the field of science and technology. Soon laser action was demonstrated in gases, liquids and other optical materials as well as in semiconductors. Today lasers come in all sizes and shapes. Some gives only nanowatts (10-9 watts) of power while others produce several terawatts (1012 watts) of power. Some operate continuously while a few others produce pulses which lasts only for a few femtoseconds (10-15 seconds). Laser is a unique source of light that differs, fundamentally from ordinary sources of light. The light generated by a laser is