Lasers
The twentieth century saw many of the inventions which tremendous helped in the development of mankind and lasers, are undoubtedly one of them. LASER is an acronym for Light Amplification by Stimulated Emission of Radiation. In simple terms, it is a device which emits a concentrated beam of monochromatic (single color) light. The light produced is coherent, meaning that all the light waves emitted are in the same frequency. They are therefore in tandem with each other, resulting in very less scattering. The light beam produced from a laser can be of any frequency, thus resulting in infrared lasers, ultraviolet lasers and X-ray lasers.
Basic Physics behind the Laser:
Normally, in a torch or candle, each of the energised molecules and atoms emit light randomly in various directions. However, in the case of a laser, energy is supplied to an atom, in the form of a light flash or an electrical discharge. This causes the electrons in the atom to get excited, thus releasing energy to the external light wave. This energised light beam, after several levels of amplification, is what is called a laser beam.
In commercial applications, energy is pumped into a gas or solid-filled chamber with reflective mirrors at either end. This produces the required laser beam of the desired wavelength as a result of repeated collisions with the atoms inside the chamber. For instance, in a helium-neon laser, the glass-constructed chamber is filled with a mixture of helium and neon. Pumping of the energy is done by an electrical discharge and the output is normally a red or crimson laser light.
The basic working can be understood better with the help of the following diagram.
Uses of laser:
The concentrated light beam produced by the laser has various applications in home as well as in different industries.
Manufacturing:
Laser light, because of its high energy, is used to cut and drill holes. It is also used to cut through several sheets of fabric or wood planks at one go. Wielding is also done using laser light.
Surgery:
The laser light makes it possible to illuminate a small area so brightly to enable doctors to see tiny details. Hence, they are able to precisely diagnose the internal working of the body and also perform delicate surgeries like eye surgery. The laser light is especially used to remove cancer cells.
Entertainment:
CD and DVD players utilise a beam of laser to read large amounts of information from a CD or DVD which is inserted into the player.
Shops:
Bar code readers at the super market use laser beam to read off price labels.
Space:
Lasers also find use in space for the purpose of communication , for remote sensing, and also in defense systems. Laser Spectrometers are used to measure the proportion of the chemical materials present in the matter, besides their general composition.
Recently,the powere of a laser beam has also been found to trransform light into sound. To do so, a laser pulse which is traveling in water, is compressed so that it can ionise some amount of water. The ionised water absorbs the laser energy and gets heated up, resulting in a breif explosioin of steam that generates up to a 220 DB sound pulse.
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