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Biblioteca Terra: Microscop, microscoape optice
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Sectiunea Diverse - Microscopul
pagina a fost realizata de Teodor



Microscoape
Ochiul uman poate vedea obiecte mici pana la circa o sutime de milimetru in diametru. Bacteriile mari si alte organisme unicelulare sunt de 100 de ori mai mici decat aceasta valoare, iar virusii sunt de zeci de mii de ori mai mici. In ultimii 350 de ani, microscoapele au permis observarea unor astfel de obiecte mici, iar unele dintre microscoapele moderne sunt sufficient de puternice pentru a ne arata atomi individuali.

Microscoape Optice
Microscoapele optice utilizeaza lentile pentru a produce, prin refractia luminii, imagini marite. Primele microscoape au fost probabil microscoapele compuse realizate in anii 1590 de mestesugarul olandez Zacharias Janssen (1580 1638). Microscoapele compuse poarta aceasta denumire deoarece ele folosesc o combinatie de lentile pentru formarea imaginilor.
La sfarsitul secoluluinal XVII-lea, Robert Hooke (1635 1703) a utilizat un microscop compus pentru a realize desene detaliate ale celulelor si animalelor mici. Gradul de marire a fost limitat de distorsiune pana in 1830, cand au fost inventate lentilele cu distorsiune redusa. In 1865, microscoapele l-au ajutat pe chimistul francez Louis Pasteur (1822 1895) sa demonstreze ca bolile infectioase erau cauzate de microorganisme.

Limita Rezolutiei
Chiar daca ar utilize lentile ce nu creeaza nici un fel de distorsiune, microscoapele optice nu ar putea prezenta, sau arata detalii, decat pentru obiecte mai mari ca lungimea de unda a luminii vizibile. Aceasta valoare este de aproximativ 500 nanometri, ceea ce inseamna un grad de marire de 2000 de ori.
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