Chapter 38Serway & Beichner 6th Ed.

Fig 38-4a, p.1207

DiffractionDiffraction

D = a

P

wave front

Phasor Model

)()( 110 NEEEE NT

sin

2d

trkAE sinWhere we assume:

sin2

2

)2sin(

2

)2sin(

2

a

II

E

oT

T

E

Note: β = and ER = Eθ

)()( 110 NEEEE NT

These produces the sameinterference patterns!

a

b

D

22.1~

Diffraction from Circular Aperture

02

8II sad

Single Slit Double Slit

Diffraction and Interference

a d

1 0.5 0 0.5 1y

0

0.2

0.4

0.6

0.8

1

langiS

Single Slit Diffraction vs Aperature Size

y/y o

x

= .633 ma = 5.0 ma = 2.5 m

2

0 2/

2sin

yy

sin

2 a

1 0.5 0 0.5 1y

0

0.2

0.4

0.6

0.8

1

langiS

Single Slit Diffraction vs Wavelength

Diffraction also depends on wavelength!

a = 2.5 m

x

y/y o

2

0 2/

2sin

yy

sin

2 a

-0.4 -0.2 0 0.2 0.4y

0

1

2

3

4langiS

Double Slit ; 0.633 m; a2.5 m;d5 m

-0.4 -0.2 0 0.2 0.4y

0

1

2

3

4

langiS

Double Slit ; 0.633 m; a2.5 m;d10 m

MissingPeaks!!

Diffraction Modifies the Interference Pattern!!

-0.4 -0.2 0 0.2 0.4y

0

100

200

300

400

500

600

langiS

N Slits ; 0.633 m; a2.5 m;d5 m; N5

-0.4 -0.2 0 0.2 0.4y

0

200

400

600

800

1000

1200

langiS

N Slits ; 0.633 m; a2.5 m;d5 m; N6

-0.4 -0.2 0 0.2 0.4y

0

2107

4107

6107

8107

langiS

N Slits ; 0.633 m; a2.5 m;d5 m; N8

Primary

Fig 38-29, p.1226

Polarization: Defined as the direction of E-field!

Linear, Circular, Elliptical

Fig 38-28, p.1225

Circular Polarization

Elliptical Polarization

Polarizers

Fig 38-32, p.1228

Fig 38-33, p.1229

Fig 38-34, p.1229