Cpter 23 Geometric Optic
Ligt Wt i ligt? Wve or prticle? ot Geometric optic: ligt trvel i trigt-lie pt clled ry Ti i true if typicl ditce re muc lrger t te wvelegt Geometric Optic 2
Wt it i out eome ddreed y geometric optic: ropgtio: ligt goe i trigt lie eflectio: gle of icidece = gle of reflectio efrctio: Sell lw eome ot ddreed y geometric optic: olriztio Diffrctio Iterferece otoelectric effect Electromgetic teory Qutum mecic Geometric Optic 3
eflectio d efrctio icidet gle r r reflectio gle refrctio gle medium (e.g. ir) medium (e.g. gl) Te icidet, reflected, d refrcted ry, d te orml to te urfce, ll lie i te me ple Geometric Optic 4
Speculr d Diffuive eflectio we ll dicu ti oe peculr reflectio: moot iterfce, defiite reflectio gle diffuive reflectio: roug iterfce, cttered reflectio Geometric Optic 5
' Imge Oject poit: were te ry ctully come from Imge poit: were te ry pper to come from mirror : oject ditce : imge ditce oject poit ' imge poit ere outgoig ry do ot ctully come from imge i virtul if tey did, te imge would e rel Geometric Optic 6
Sig ule for Ditce 0 ' 0 Oject ditce: we te oject i o te me ide te icomig ligt, >0, oterwie, <0 Imge ditce: we te imge i o te me ide te outgoig ligt, >0, oterwie, <0 oject poit ' imge poit mirror Geometric Optic 7
Sig ule for Ditce 0 ' 0 Oject ditce: we te oject i o te me ide te icomig ligt, >0, oterwie, <0 Imge ditce: we te imge i o te me ide te outgoig ligt, >0, oterwie, <0 oject poit ' imge poit refrctig iterfce Geometric Optic 8
Lterl Mgifictio Q ' Q' m y' y y oject ' imge y' mirror: ' m eed t let two poit (,Q) to figure it out Geometric Optic 9
Iverted d evered Imge Imge c e erect (rigt ide up) or iverted (upide dow) ole mirror cmer ocur Imge c e revered ( mirror-imge left d look like rigt d vice ver) pli mirror imge i virtul, erect, d revered Geometric Optic 0
eflectio i Spere Equtio re ivolved deped o α Geometric Optic ' C B t ' t t ' V
eflectio i Spere Ue prxil pproximtio Geometric Optic 2 ' C B t ' t t ' V
Spericl Mirror eflectio ' 2 ' o α depedece! ' Geometric Optic 3
Focl oit 2 oject i fr wy to te left ' ' f 2 F focl legt Geometric Optic 4
Focl oit 2 oject i plced i te focl poit f 2 F work i ot wy Tee tig re pproximtely true for pericl mirror. Tey re exctly true for prolic mirror. Geometric Optic 5
Spericl Mirror: >f ' f ' F f ' f ' 0 Geometric Optic 6
Spericl Mirror: <f ' f F imge i virtul f ' ' f ' 0 Geometric Optic 7
Spericl Mirror Mgifictio y' ' Q m y y y' C ' Q' ' V ecue trigle QV d Q V re imilr >0: imge i rel d iverted (m<0) <0: imge i virtul d erect (m>0) Geometric Optic 8
Covex Spericl Mirror covex = curvig out All i exctly te me except tt f (d ) i egtive cocve covex ' ' ' ' Geometric Optic 9
Focl oit of Covex Mirror focu i virtul provided >0, covex mirror lwy form virtul, erect, revered imge (me te pli mirror) F m= for pli mirror m< for covex mirror Geometric Optic 20
ricipl ry Need tem to fid imge poitio d mgifictio Q C ' Q' F B V A QBQ : ry prllel to te xi reflect troug focl poit QAQ : ry troug focl poit reflect prllel to te xi QCQ : ry troug te ceter reflect ck QVQ : ry to te vertex form equl gle wit te xi Geometric Optic ti cotructio eglect errtio Geometric Optic 2
Sell lw Ti i te ic lw of refrctio medium (e.g. ir) medium (e.g. gl) gle of icidece ot equl to gle of refrctio! i i : idex of refrctio wt i ti? Geometric Optic 22
Idex of efrctio = rtio of te peed of ligt i te mteril to tt i vcuum c v >: ligt trvel lower i te mteril t i vcuum Wt cge we te ligt pe from oe medium to oter? * Frequecy? No, it would imply cretig/detroyig wve * Speed? Ye, ecue te medi ve differet * Wvelegt? Ye, ecue λ=v/f Geometric Optic 23
Totl Iterl eflectio Sell lw my give iθ> wt doe it me? Tere re lwy two ry: reflected d refrcted At ome gle, te refrcted ry dipper i Geometric Optic 24 C c oly ppe if criticl gle
Fier Optic Ligt c e trmitted log fier wit lmot o lo due to totl iterl reflectio Due to impurity of gl, te igl evetully degrde (typicl rte re ~50%/km) Widely ued i commuictio muc iger frequecy t for regulr wire, terefore c trmit muc more dt Geometric Optic 25
efrctio t Spere Geometric Optic 26 B t ' t t ' V C
efrctio t Spere Geometric Optic 27 B t ' t t ' V C
efrctio t Spere Ue Sell lw Geometric Optic 28 ) ( ) ( ' m ' mgifictio: i i
Ti Le Le = opticl ytem wit two refrctig urfce 2 2 ' ' 2 ' Ti le: ' 2 Geometric Optic 29
Ti Le Equtio Geometric Optic 30 2 2 2 ', ' ',, 2 umptio: f ) ( ' 2 2