The diffraction of light waves
The diffraction of light waves
Agenda today 1.Single slit diffraction 2.Diffraction by a circular aperture 3.Optical grating 4.X-ray diffraction32
Agenda today 1. Single slit diffraction 2. Diffraction by a circular aperture 3. Optical grating 4. X-ray diffraction32
Diffraction Fresnel diffraction:ifa source s and the viewing screen are each a finite distance from an intermediate object,the resulting diffraction pattern is called fresnel diffraction(菲涅尔衍射）
Diffraction Fresnel diffraction：if a source s and the viewing screen are each a finite distance from an intermediate object, the resulting diffraction pattern is called fresnel diffraction(菲涅尔衍射）。 P
Fraunhofer diffraction:if both the source and the screen are far from the intermediate object,the diffraction is called fraunhofer diffraction(夫朗和 费衍射)。 D
Fraunhofer diffraction：if both the source and the screen are far from the intermediate object, the diffraction is called fraunhofer diffraction(夫朗和 费衍射）。 P
Single slit diffraction(单缝衍射) 夫琅禾费单缝衍射 2 S 0 B
Single slit diffraction(单缝衍射）
For constructive asin0=±(2k+1) interference For destructive asin0=±kλ minima interference 2 0 -2
For constructive interference ： sin (2 1) 2 a k a k sin minima01-2-12 For destructive interference
asi o A 0 D 入/2 a 几 asin=n 2
oP BA asin a sin 2 a n /2
2 0 -2 asin0=±k入 the angular width of<asin< central maxima: Φ=20≈2sin0= 22 a
0 1 -2 -1 2 the angular width of central maxima： a k sin asin 2 2 2sin a
Diffraction pattern with different slit width: 0.16mm 0.08mm 0.04mm 0.02mm
Diffraction pattern with different slit width: 0.16 mm 0.08 mm 0.04 mm 0.02 mm
Intensity in single-slit diffraction For point o0=0,△p=0 △E Eo Eo For point P:Ep<Eo Ep △E
Intensity in single-slit diffraction For point o = 0 , = 0 E0 E0 …… E0 = N E0 For point P： EP < E0 EP E0