Laser

Laser is a very powerful light beam strong enough to carry enormous amount of energy, cut through metal and travel vast distance. It does not exist in nature - laser is a human technology. There are many kinds of lasers used in different ways, e.g. small lasers in CD and DVD players, bar code readers in stores, lasers used to delicate surgeries, to produce cars, to cut many layers of fabric at once in clothing factories.

Unlike natural light like sunlight, lasers are monochromatic (which means they contain only one color or wavelenght), coherent (all the wavelenghts move in the same way) and collimated (so all the waves travel in the same direction). All of laser energy is focused to produce a small point of intense power and that makes laser light precise and useful for cutting. Lasers are also used in spectometers - device that detects what gases the air contains or even how much methane is present in atmosphere.

The word 'laser' is an acronym for Light Amplification by Stimulated Emission of Radiation and it is a good definition how lasers work. It starts off with weak light but more and more energy is added by pumping photons with more energy through collisions with other photons – this is the light amplification. Then, atoms in ruby crystal soak up this energy and give it off as a new photon of light radiation. Photons hit excited atoms so they give off two photons instead of one – this is called stimulated emission. Mirror at one end of the laser keeps the photons bouncing inside the crystal and a partial mirror at the other end lets some photons escape.

Do you think that laser is a Greek invention? Speak if it's Greek and check the answer!