semafor záver zmierniť how do lasers work Maryanne Jones zástava poľnohospodári
How lasers work | Hypertherm
How Fibre Lasers Work | Optoelectronics Research Centre | University of Southampton
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Lasers, explained by RP Photonics Encyclopedia; principle of operation, properties of laser light, applications, resonator, laser beam, stimulated emission
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