The Science of Laser Beams

lasersIn What Way the Lasers are used for?

Lasers are now playing a major role not only in communication but also in precise machining, cutting, drilling and welding. This is due to their enormous power which can generate temperatures of 4000 degrees centigrade quite easily over a very small localized area. This high temperature is enough to melt and evaporate even tungsten.

Lasers are also increasingly being used for surgery because of their precise control and versatility. In the nuclear industry, Lasers are being used for uranium isotope separation. There are different types of Lasers were developed including high power carbon dioxide, copper vapour, ND-YAG and excimer Lasers. Some of these are used in metal welding and drilling and even shaping and cutting diamonds. Others are used as surgical tools instead of the surgeon’s knife.

The highest power Lasers are being developed for Laser included nuclear fusion which aims to duplicate the sun on the surface of the earth. By creating instantaneous temperatures of higher than 50 million degrees for one nano-second hydrogen or its isotopes deuterium or tritium may be induced to fuse to produce helium. This transition would result in converting the mass difference into energy according to the well known relation E=mc2 propounded by Albert Einstein where ‘E’ stands for energy, ‘m’ stands for mass and ‘c’ denotes the velocity of light.

The experimental arrangement called the National Ignition Facility in USA consists of fuel chamber containing a mixture of deuterium and tritium (D-T). In this, 192 Nd-glass lasers, each with pulsed power of over 500 Mega Watt, will be directed synchronously in a multi-armed manner. The energy produced will be 1.8 million Joules equivalent to 10 TeraWatts (1013 W), where one Watt is one/Joule/second.

The system set up in the USA was strangely enough, called Shiva. The Nd-glass Laser was chosen because of its very high energy storage density which could be discharged in a very short time of 0.2 nano seconds. It is estimated that still higher total powers up to one PetaWatt (1015 Watt) are required to reach the break even point where the power output due to fusion will be larger than the power input. Such a giant Laser under construction at the Lawrence Livermore Laboratory USA may hold the key to the ever increasing demand for power in the 21st century, with hydrogen being provided from the apparently inexhaustible seawater.

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