Giáo trình vật lý đại cương phần quang học ths nguyễn hoàng tuyến, ths nguyễn thị ngọc vân

BQ GIAO DUG VA DAO TAO TRLfONG DAI HOC DAN LAP Clju LONG Nguyen Homing Tuyen - Nguyen Thi Ngoc Van Gido Trinh VAT LY DAI ClWNG Phan Quang Hoc LiCu hdnh noi bo TM&G DaI HQCeiSUFOlU LOW Vinh Long - 2009 ■ Ldl DE TVA Trttfng Dai hoc Dan lap Cftu Long muon khang dinh la trung tarn dao tao nguon nhan lite co trinh cao cho khu vile dong bang song Cifu Long de phuc vu cho cong cuoc cong nghiep hoa, hien dai hda dat nifdc thi phai nang cao chat lifcrng dao tao toan dien Mot nhtfng yeu to yeu la doi ngu thay co, he thong cac giao trinh va trang thiet bi day hoc Cung vdri cdc nganh cdc cap toan quoc dang day nhanh tien xay difng va cung co vi the xu the hoi nhap, tnrcrng Dai hoc Dan lap Cdu Long dan thng biidc hoan thien de difctag dau vdi nhtfng thach thtfc do, gop phan difa nen giao due dai hoc Viet Nam dtfng vifrig, ngang tarn khu vifc va the gidi Ke hoach xay difng ve mot Bo giao trinh suf dung cho cac giang vien lam tai lieu co ban de giang day, cho sinh vien nghien cdu tham khao hoc tap la nhu cau cap bach cua nha trifefng An pham la giao trinh Vat Ly Dai Cifcfng - Phan Quang Hoc cua Khoa Khoa Hoc Ccf Ban, Tnfbng Dai hoc Dan lap Cufu Long, ThS Nguyen Hoang Tuyen va ThS Nguydn Thi Ngoc Van bien soan Lanh dao triferng Dai hoc Dan lap Cdu Long tran nhffng cong hien, dong gop cua Quy thay co mefi giang cung nhif cac thay co can bo - giang vien cP htfu cua nha trifefng Hy vong r&ng, mot khong xa Trirtrng Dai hoc Dan lap Cufu Long se c6 day du mot Bo giao trinh hoan chinh dung nha trufrng Tran gidi thieu giao trinh den Quy thay co va cac em sinh vien trildng Dai hoc Dan lap Cdu Long Vinh Long, thang 09 nam 2009 Q HIEU TRtfdNG ThS Nguyen Cao Dat QUANG HOC Quang hoc 1& mot phan cua vat ly hoc chuyen nghien ctfu ve dnh sdng sir tifong tdc cua dnh sdng vdi cdc chat • Vao cuoi the ky XVII, Newton diTa vao ti'nh truyen thang cua anh sang da dtfa thuyet hat don gian ve anh sang Sy phan xa va khuc xa anh sdng diTtfc thuyet giai thich bang quan diem cd hoc • Cung thcri gian ay, Huygens lai difa thuyet song anh sdng nhSm giai thich cac hien tiTc/ng giao thoa, nhiSu xa va phan cite ma thuyet hat cua Newton khong giai thich noi • Den nam 1865, Maxwell da chilng minh rang cac triTcrng dien tu" bien thien lan truyen khong gian vdi van toe anh sdng Nhif vay, ong da xac nhan anh sang la song dien tor - c6 birdc song ter 0,40pm den 0,76pm Thuyet song dien tir ve anh sang da cho phep giai thich tot cac hien tirqng mang tinh chat song cua anh sdng (giao thoa, nhidu xa, phan cifc, tan sSc) Tuy nhien, thuyet khong the giai thich diTOc hieu ting quang di$n, sir tan xa Compton, nhiing khia canh hat cua anh sang diTOc the hien • Vao the ky XIX va dau the ky XX, xuat hien khai niem hat anh sang : anh sdng gom mot dong hat goi la photon lan truyen theo cac dinh luat lan truyen cua song dien tir Do la thuyet liTOng td anh sang cua Einstein Theo do, anh sang phat hay hap thu nhiing photon, day la nhiing liiong gian doan md nang liiqng cua chung phu thuoc vao tan so” Nhii vay theo thuyet liiong td ve anh sang, anh sdng vda co tinh song vda co tinh hat, goi la liidng tinh song - hat - Trong mot so' hien tirong nhii giao thoa, nhieu xa, phan ciic, anh sdng the hien tinh chat song - Trong cac hien tiiOng khac nhii hi$u dng quang dien, hieu dng Compton anh sang lai the hien tinh hat Chitcfng nhCng cd sd CUA QUANG hinh hoc va QUANG HOC SONG I NHUNG CO Sd CUA QUANG HINH HOC Quang hinh hoc la mon hoc nghien cufu cac hien tiTcfng anh sang difa tren quan niem ve tinh truyen thing cua dnh sdng No dat cd sd tren nhang dinh luat sau : Dinh luat truyen thang ciia anh sang Trong moi truang sudt, dong chdt vd dang hudng, anh sang truyen di theo ditdng thang PhiWng truyen cua dnh sang goi la tia sdng M6i chum sang chtfa vo so" tia sang Dinh luat ve tac dung dpc lap cua tia sang Tdc dung cua cac chum sang khde Id doc lap ddi vdi nhau, nghia la Id tdc dung cua mot chum sang khong phu thuoc vdo su co mdt hay khong cua cac chum sang khde Dinh ; luat phan xa va khuc xa anh sang ciia Descartes Khi tia sang SI tdi mat phan each (£) gitfa hai moi trtfcfng suot, dong chat va ding hifdng thi no bi tach hai tia: tia phan xa IR1 va tia khuc xa IR2 Hai tia tuan theo hai dinh luat sau day : a) Dinh luat phan xp anh sang Tia phan xa ndm mdt phdng tai va goc tai bang goc phan xa i = i' b) Dinh luat khuc xq anh sang Tia khuc xq ncim mat phdng tai va tl so giUa sin goc tai va sin goc khuc xq la mot hang sd' Ri S N (1) (Z) R2 (2) sin i -7 - - n21 sinr (1) • (S) la mat phan edeh moi trifcrng • IN (E), IN la phdp tuyen cua (Z) ■ • Mat phdng (SI, IN) goi la mat phdng tdi • Hang so” n2i goi la chiet suat ty doi cua moi trifdng (2) ddi ¥di moi trufrng (1) 1121 phu thuoc ¥ao ban chat cua hai moi trifbng ¥a mau sac cua tia tdi SI Ly thuyet va thilc nghiem chtfng to : n2i = —, v2 ¥^¥2 lan hrot la ¥an toe anh sang cac moi trirdng (1) Ơa (2) ã Chiet suat ty ddi cua mot moi tri/crng bat ky ddi ¥di chan khong goi la chiet suat tuyet ddi cua moi trifcrng do, ky hieu n c n=— v vdi v la van toe dnh sang moi trifcrng dang xet, c la van toe anh sdng chan khong c > v => n > DSc biet doi vdi khong v^ « c nen n^ « Goi n],n2 la chiet suat ty dol cua moi trirdng (1), moi trtfcfng (2) doi vdi chan khong, tdc chung la cac chiet suat tuyet doi cua cac moi tru’dng Vi c c no n21 = — = — : — = — v2 v2 vx nl Neu moi trifdng (1) (2) la khong nj «1 => n21 a n2 Vay chiet suat tuyet doi cua mot moi triTcfng cung diftfc coi la chiet suat ty doi cua moi trifdng d6 doi vdi khong The (2) vao (1), ta dutfc : sin i _ n2 sin r n} n! sin i = n2 sin r Quy udc ndi tat : nj la chiet suat moi trufrng tdi, n2 la chiet suat moi trdcrng khuc xa Dinh ly Malus Dinh ly co lien quan den hai khai niem : quang lo va mat song hinh hoc a) Quang Ip Quang lo cua anh sang tren doan dirdng AB mot moi trifdng dong chat la mot dai luttng bdng tfch so' gitta chiet suat n cua moi tmerng vdi dai cua doan dufrng AB ma anh sang di duttc moi treferng ay Ky hieu quang lo : L hay [AB] L = [AB] = nl (n) B / A Neu anh sang lan Ihtft di qua nhieu moi truhng dong chat co chiet suat , n2, n3, tren cac doan dhbng thcfng hng AM, MN, NO, co dhi lan Ihqt la lo tren doan dhbng tong cong la : , 12, I3, thi quang [AMNO ] = [AM] + [MN] + [NO] + L = n^j + n2l2 + n313 + L = Xni1i Trifcrng hap anh sdng truyen th A den B moi trirbng co chiet suat thay doi lien tuc th diem sang diem khac, ta chia cung dhdng di AB cua anh sang nhhng doan cung nguyen to dl cho tren moi doan chiet suat n xem nhh khong doi B dl (n) A Khi : L= Ja ndl Y nghia cua quang 16 : rB q fl Ja v J/ L= I -dl = c J['Bdl a v rB - C JA dx = CT , 94 Do : APX ~ V2m(U - E) Difa vao he thufc bat dinh, ta viet : Ax « h ARx h 72m(U - E) Rd rang la neu Ax > d (be day cua hang rao the) thi hat cd the vuqt qua hang rao the nang Cu the, dieu kien de cho hat vi mo vu’o't qua diXOc hang rao the nang U la : , h > d hay -V2m(U-E) < V2m(U-E) h Vdi dieu kien do, mac du hat co nang liTOng nhd hon U, nhitag nd vdn cd kha nang vu’o't qua hang rao the nang Do la hieu ling difd'ng ham Ta xet cac vl du : • Neu U - E = 10 18 J , m « 10 31kg (khoi litong electron), d «10r10m (kich thitdc nguyen tut), thi : -V2m(U-E) »0,2 x Dao dpng trf dieu hoa Hat vi mo chuyen dong theo phtTOng x tru’cfng the U = 77 kx2 diTOc goi la dao dong tuf dieu hoa Dao dong td dieu hoa la mot hien tuttng bien vat ly Dao dong cua nhtfng ion xung quanh nut mang tinh the, dao dong cua nguyen ttf phan ttf , deu cd the xem la cac 96 dao dong td dieu hoa Bai todn ve dao dong td dieu hoa difqc dng dung trite tiep nhdng van de ly thuyet cua co hoc IdOng td nhit ly thuyet bdc xa can bdng, ly thuyet pho, thuyet nhiet dung rieng cua phan td hai nguyen td, Ta se xet nang liTOng cua dao dong td dieu hoa The edng thde the nang cua dao dong dieu hoa U = mco2x2 (m: khoi lirqng hat, co: tan so goc, x: ly do) vao phitong trinh Schrodinger, ta difqc : d2T 2m T? mco x T = dx2 + h2 IL — Giai phdcmg trinh nay, ta thu doqc bieu thde nang lifqng cua dao dong td : En = Aco ( n + 1— I , I : n = 0,1,2, NhiT vay, nang liftfng cua dao dong td bi lurc/ng td hoa Nang liTOng thap nhat cd a dao dong td dng vdi n = Eo =—h® Nang ItTOng goi la nang lifong “khong” Nang lilo'ng “khong” lien quan chat che tori dao dong “khong” cua dao dong td, nghia la nhiet T -> 0, dao dong td vdn dao dong Dieu da difqc thifc nghiem xac nhan thi nghiem tan xa cua tia X qua tinh the d nhiet thap Neu d nhiet thap mang tinh the khong dao dong thi khong co tufcfng tdc gida tia X va mang, nhif vay khong co tan xa Nhifng thdc nghiem xdc nhan cd tdn xa tia X nghia la co dao dong cua mang d nhiet thap Sit kien chdng to tinh dung ddn cua ccr hoc lirqng td 97 Nang lifting “khong” cung la ket qua trifc tiep cua he thtfc bat dinh Thifc vay, neu 6r T = 0°K dao dong tuf khong dao dong, c6 nghla la ta xdc dinh diftic dong thdi toa (x = 0) va dong lifting (P = 0), dieu trai vdi he thdc bat dinh 98 hUOng dAn va dap so Chuforng Stf giao thoa anh sang 1) i = 0,6mm, xt= 0,3mm ; 0,9mm ; 1,5mm ; n' = l,33 2) d = 10,5cm ; i = 1mm, e = 6,4p.m 3) sq = 1,578m ; i = 0,25mm ; N = 21 van 4) i = 2,7xl0'1 3m 5) i = 0,3mm ; MN = 12mm 6) van sang ; van toi (xet hieu quang 16 tai A ) 7) e = 6xl0“3 mm 8) X = 0,6qm 9) emin=0,llxl0-3 mm 10) cc = x 10 4rad 11) X = 0,589p.m 12) K = 5; , X, = 0,5p.m Chtfofng Stf nhieu xa anh sang 1) b max = lm ■ 2) dSk = Rb Tt - —A R+b 3) rj = 0,5mm ; 0,71mm ; 0,86mm ; 1,00mm 4) b = 3RX-xf ’ Ax = 6mm ; 99 5) r = 1mm 6) X = 7) (R + bXrf-rf) 2Rb -KSLxk Pk = Po R + r0 Pt = Rrp A.2p R + r0 (p = 1,2,3, ) • 8) = 2—= 1,2cm b 9)