Inaugurating the yearlong celebrations of the 125th birth anniversary of mathematician Srinivasa Ramanujan, the Indian Prime Minister Dr. Man Mohan Singh declared December 22, Ramanujan's birthday, the National Mathematics Day and 2012 the National Mathematics Year. It will certainly be a tribute to an extraordinary mathematician of India.

For a long time, we have been using light to send messages from one place to another. The flashing of sunlight from polished metallic surfaces, hand held mirrors, the photographs etc. had long been accepted as the methods of conveying simple in formations. Our forefathers had been using lighting fire beacons which was a very important method of sending information. Light lamps were used until very recently on naval ships for communication.

You would have noticed that when an electric bulb or any common source of light is switched on, the light rays are spread in all directions and thus illuminate the entire room in which a source is lighted. Unlike it there is a peculiar source of light which produces a narrow, intense and parallel beam of light which is known as laser. In fact, laser is an acronym for Light Amplification by Stimulated Emission of Radiations.