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Optical Radiation > Laser
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Basic Principles, Definitions
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Laser is an acronym for “Light Amplification by Stimulated Emission of Radiation" and relates to the way of radiation generation. The laser is a relatively recent invention. It was for the first time realized in 1960 with a synthetic ruby crystal. In order to produce a laser beam a laser medium has to be energized by an external energy source (referred to as “pumping”). Many materials as e.g. solids, semiconductors, dyes or gases are used as a laser medium. Laser beams have many remarkable properties and there-fore have found applications in many fields.
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Applications in Everyday Life and Technology
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The remarkable properties of laser radiation resulted in many technical applications. It is used in production technology, for measurements, spectroscopy and holography. Laser-shows are very popular but compliance with protection measures is mandatory. Semiconductor lasers also known as laser diodes have important advantages. Therefore low power laser diodes are used in every day life, e.g. in laser pointers, laser printers, and CD/DVD players. Information technology takes advantage of the fact that laser radiation can be easily relayed in fibre optic cables.
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Medical Applications
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Medical applications of laser are mainly based on its strong focusing and high power density. Moreover one takes advantage of the possibility to relay the laser light through flexible optical fibers. Thus endoscopic surgery with lasers is possible. Most laser applications in medicine aim at ablation, abscission or vaporisation of tissue or coagulation of body fluids.
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Biological and Health Effects
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Biological and health effects of laser radiation are similar to those of normal optical radiation. They depend strongly on wavelength. The range of wavelength of laser radiation extends from approx. 10 000 nm to approx. 200 nm, i.e. from infrared via visible light to UV radiation. Since penetration depth into biological tissue is relatively low mainly skin and eyes are affected if laser radiation impacts accidentally on humans. Particular danger exists for the eyes due to their optical properties. The very high power density and the strong focussing of laser beams can result in special health risks.
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Safety Measures
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The remarkable properties of laser radiation and the biological effects resulting from the use of laser light require special safety measures when using laser radiation. For determining these measures lasers are classified into safety classes according to their potential to produce damage. For the general public safety measures for so called laser shows and for the use of laser pointers are necessary.
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