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Efectul Laser

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Efectul Laser
Efectul laser
Laserul este un dispozitiv optic care generează un fascicul coerent de lumină. Fasciculele laser au mai multe proprietăți care le diferențiază de lumina incoerentă produsă de exemplu de Soare sau de becul cu incandescență: * monocromaticitate — un spectru în general foarte îngust de lungimi de undă; * direcționalitate — proprietatea de a se propaga pe distanțe mari cu o divergență foarte mică și, ca urmare, capacitatea de a fi focalizate pe o arie foarte mică; * intensitate — unii laseri sînt suficient de puternici pentru a fi folosiți la tăierea metalelor.
La origine termenul laser este acronimul LASER format în limba engleză de la denumirea light amplification by stimulated emission of radiation (amplificare a luminii prin stimularea emisiunii radiației), denumire construită pe modelul termenului maser care înseamnă un dispozitiv similar, funcționând în domeniul microundelor.
În limba română forma de plural recomandată de dicționare este lasere; cercetătorii implicați în acest domeniu preferă însă pluralul laseri.
Istoric
Principiile de funcționare ale laserului au fost enunțate în 1916 de Albert Einstein, printr-o evaluare a consecințelor legii radiației a lui Max Planck și introducerea conceptelor de emisie spontană și emisie stimulată. Aceste rezultate teoretice au fost uitate însă pînă după cel de-al doilea război mondial.
În 1953 fizicianul american Charles Townes și, independent, Nikolai Basov și Aleksandr Prohorov din Uniunea Sovietică au reușit să producă primul maser, un dispozitiv asemănător cu laserul, dar care emite microunde în loc de radiație laser, rezultat pentru care cei trei au fost răsplătiți cu Premiul Nobel pentru Fizică în 1964.
Primul laser funcțional a fost construit de Theodore Maiman în 1960 și avea ca mediu activ un cristal sintetic de rubin pompat cu pulsuri de flash.
Primul laser cu gaz a fost construit de fizicianul iranian Ali Javan în 1960 folosind un amestec de heliu și neon, care producea un

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