LASER

The word laser stand for light amplification by stimulated emission of radiation. The unique property of laser , emission of coherent light , makes the applications of laser cutting and lithography possible.

Laser pointing is also an application based on the property of the laser to follow a narrow path over great distances.

Laser finds a place in optical disk drives , laser printers , optical fibers , bar code readers , laser surgery , dermatology , cutting , welding , photo rejuvenation , endarterectomy   , military law enforcement device for locating targets and measuring range and speed , and laser lighting displays in entertainment .

Application of lasers

Defence  The purpose of knocking down an enemy tank requires that the range is accurate . High intensity and low divergence of the laser satisfies this need . Neodymium and carbon - dioxide lasers are as standard items for artillery and tanks .  Laser range finders are lightweight having reliability and superior range accuracy .

When a laser beam is directed towards the target and reflected light from the target is received by optical system and detected , corresponding time taken is measured . Half the time recorded is multiplied by the velocity of light and product to calculate range . 

Data storage : Optical techniques play a major role in storage of high - density data . These are based on the principle that  , when a powerful laser illuminates a thin layer of metal , its optical properties change . As a laser can be focused on points smaller then one micro diameter , it takes less then one square micro to record one bit of data. There are laser CDs and DVDs available in the market with the required data stored in the form of audio , video  , document , etc .

Holography : The technique of obtaining an image of a  3D body on a 2D photographic plate is termed as holography .The stored image is called hologram . The  whole process is based on the interference produced by the interaction of two beam monochromatic light waves under certain conditions .

The hologram is recorded when  a part of emitted laser beam  or reference beam goes directly to the photographic plate and the other part being object beam is reflected from the object and made to fall on the photographic plate , hence interfering with an interference pattern , which is called a hologram .

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