The document discusses several topics in physical optics including: 1) Double-slit interference and how constructive and destructive interference occur based on the path difference between light waves. 2) Thin-film interference caused by light reflecting off the top and bottom surfaces of a thin film, which can produce colorful interference patterns. 3) Diffraction at a single slit and how the diffraction pattern is determined by the slit width and wavelength of light.

1. BahanKuliahFisikaDasar2
OptikaFisis
oleh
Ishafit
http://hafit.pfis.uad.ac.id
Program StudiPendidikanFisika
UNIVERSITAS AHMAD DAHLAN
YogyakartaHubble Space Telescope

2. OptikaFisik(PysicalOptics)
|Optical Interference (IntefrerensiOptik)
zDouble-Slit Interference
zThin-Film Interference
|Optical Diffraction (DifraksiOptik)
zSingle-Slit Diffraction
zDiffraction Gratings
|Polarization oh Light (PolarisasiCahaya)

3. Physics Phenomenon
Newton's RingsA band of color appears wherever the distance between the two pieces of glass causes light of that color to interfere constructively, making the waves bouncing off the two surfaces reinforce each other ©1993-2003 Microsoft Corporation. All rights reserved.

4. Physics Phenomenon
Thin-film interferenceThin-film interference is the interference of light waves reflecting off the top surface of a film with the waves reflecting from the bottom surface.If the thickness of the film is on the order of the wavelength of light, then colorful patterns can be obtained, as shown in the image below,

5. Physics PhenomenonCharacteristic SpectraEvery chemical element has a characteristic spectrum, or particular distribution of electromagnetic radiation. Because of these “signature” wavelength patterns, it is possible to identify the constituentsof an unknown substance by analyzing its spectrum; this technique is called spectroscopy ©1993-2003 Microsoft Corporation. All rights reserved.

6. Double-Slit Interference
•Physics Working Model

7. Physics Working ModelConstructive InterferenceWevefrontWevefront
Light Source
Destructive Interference

8. Double-Slit Interference (Young Interference)
|Interferensioptikdapatterjadijikaduagelombang(cahaya) secarasimultanhadirdalamdaerahyang samaS1S2d θθ PySumbusistemr1r2rΔ)sin(111tkrmωψψ−= )sin(222tkrmωψψ−= L1mψ 2mψ mψ 1kr2kr δδψψψψψcos2212221mmmmm++= )(1212rrkkrkr−=−=δ rrrΔ=−= λπλπδ2)(212 θsindr=Δ

9. Double-Slit Interference (Young Interference)
|Interferensikonstruktifterjadijika:
πδn2=L,2,1,0=n λθnd=sin πδλθ 2sin=d ππλθ 22sinnd= |Interferensidestruktifterjadijika: πδ)12(+=nL,2,1,0=n λθ) 21(sin+=nd ππλθ 2)12(sin+ =nd

10. Penentuanpanjanggelombangdenganinterferensiduacelah
Dari gambardiperoleh: L θtanLy= S1S2d θθ PySumbusistemr1r2rΔ:maka jikadL>> θsinLy= dnLyn λ = nLdyn=λ

11. ContohSoal:
|Celahgandayang berjarak0,100 mm berada1,20 m darilayartampilan. Cahayadenganpanjanggelombangλ=500 nm jatuhpadacelahdarisumberyang jauh. Berapajarakantarinterferensiterangpertamadankeduapadalayar?
•Interferensiterang(konstruktifordepertaman=1)
λθnd=sin34911000,5m1000,1m)10500)(1(sin− − − ×= ××== dnλθ Inimerupakansudutkecil, sehingga: radiansatuan dalam dengan , tansin111θθθθ≈≈
Dengandemikianordepertamaakanmunculpadajarak: mm 00,6)10m)(5,00 20,1(-311=×==θLy•Interferensiterang(konstruktiforden=2) mm 0,12212=== dLLyλθ
Jadi, jarakantarapusatmaksimuminterferensiterangadalah(y2-y1)=6,00 mm
y1
y2

12. InterferensiolehLapisanTipis(Thin-Film Interference) GejalaFisikaModel Kerja

13. Air (n=1) Soap film (n>1) Air (n=1) Incident light1800Phase change18000000Phase changeReflected lightTransmitted lightSurface 1Surface 2tDari teoridaneksperimenelektro- magnetik, diperoleh: 1.Jikan1<n2, phase gelombangcahayabergeser1800padaprosespemantulan2.Jikan1>n2, phase gelombangcahayatidakbergeserpadaprosespemantulanIntereferensidestruktifterjadiketika: med2λmt= Intereferensikonstruktifterjadiketika: med) 21(2λ+=mt

14. Panjanggelombangdimedium dapatdinyatakandenganpanjanggelombangdalamvacuum, yaitu: ncnncvλυυυλ=⎟⎠ ⎞ ⎜⎝ ⎛=⎟⎠ ⎞ ⎜⎝ ⎛==11mednmt λ =2nmtλ ⎟⎠ ⎞ ⎜⎝ ⎛+= 212
The sum of the phase changes caused by both reflections is equal to 00or 3600
(Constructive)
The sum of the phase changes caused by both reflections is equal to 1800
(Destructive) nmt λ =2nmtλ ⎟⎠ ⎞ ⎜⎝ ⎛+= 212
(Destructive)
(Constructive)

15. ContohSoal:
|Gelembungsabuntampakhijau(λ=540 nm) dititikpermukaandepanpaling dekatdenganpengamat. Berapaketebalanminimumnya? (anggapn=1,35)
|Cahayadipantulkantegaklurusdarititikpadapermukaansferisyang paling dekatdenganpengamat. Perbedaanlintasanadalah2t (t=ketebalanlapisansabun). Cahayayang dipantulkandaripermukaanpertama(lebihluar) mengalamiperubahanfase½λ(indeksbias sabunlebihbesardariudara), sedangkanpermukaankedua(bagiandalamtidak. Sehinggacahayahijauakancerahketikaperbedaanlintasanminimum ½λ, sehingga: nt22 λ =nm 100)35,1)(4( nm) 540( 4=== ntλ

16. ContohSoal:
BerapaketebalanpelapisoptikMgF2yang indeksbiasnyan=1,38 dandirancanguntukmenghilangkancahayaterpantuldenganpanjanggelombangterpusatpada550 nm padasaatjatuhnormal padakacadengann=1,50? n=1,38n=1,50sinardatangsinarpantulnm 6,99)38,1)(4( nm) 550( 4=== ntλ

17. Difraksi(Diffraction)
PerilakuPartikel
PerilakuGelombang

18. PolaDifraksi

19. Difraksi(Diffraction)

20. Single Slit Diffraction EquationD λθ=sin
(first minimum)
λθmD=sin
(m= 1, 2, 3, ……)

21. ContohSoal: Maksimumdaridifraksicelahtunggal. Cahayadenganpanjanggelombang750 nm melewaticelahyang lebarnya1,0x10-3 mm. Berapalebarmaksimumpusat(a) dalamderajat, dan(b) dalamsentimeter, padalayaryang jaraknya20 cm? 75,0m 101m105,7sin67= ××==− − D λθ 049 (a)=θ cm 46)49cm)(tan 20(22 (b)0==x

22. Diffraction Grating

23. Spektrum