PC20312 Wave Optics

Section 1:

Electromagnetism and Waves

Electromagnetic spectrum

André-Marie Ampère

(1775-1836 )

Carl Friedrich Gauss 1777-1855

Images from Wikipedia

James Clerk Maxwell 1831-1879

Michael Faraday 1791-1867

Images from Wikipedia

Image adapted from Nick Strobel's Astronomy notes at www.astronomynotes.com

E

B k

John Henry Poynting (1852-1914)

S = -1 E × B

The Poynting vector is where a beam of light is pointing.

Image from Wikipedia

Plane wavefronts

Planar surfaces of constant phasek

E = E0 exp[i(kr-wt)]

Motion in +k direction

Plane wavefrontsPlanar surfaces of constant phase

kE = E0 exp[i(kr+wt)]

Motion in -k direction

Christiaan Huygens – 1629-95Pierre de Fermat – 1608-72

Images from Wikipedia

Huygens’ wavelets

Click to Huygens’ wavelets demo

Or go to

http://www.acoustics.salford.ac.uk/feschools/waves/diffract3.htm

Fig 1.1 Snell’s Law by Fermat

Image courtesy of A. Pedlar

Fig 1.2 Law of reflection by Fermat

h1

h2

x l - x

S

P

i r

l

0dx

dL

Tutorial problem:

• Write optical path length, L, between S and P as function of x

• Find

• i = r when

dx

dL

Fig 1.3 Refraction at a spherical surface

S P

Sosi

C

R

l oli

A

Imaging with a curved surface

S1 P1

S2

S3

P3

P2

C

Fig 1.4 Imaging with a lens

S P'P

So,1 Si,1

Si,2

So,2

Image formed by 1st surface acts as a virtual object for 2nd surfacen1 n2

n1

d