Introduction to OpticsPhysics 313/313H

Matt DeCamp

DeCamp Research

S. Takada, Proteins (2001)

Use 40 femtosecond (10-15sec) laser

pulses to study motion of complex

molecules

Laser system in Sharp 012

I am an Atomic, Molecular, and

OPTICAL (AMO) physicist.

DeCamp Research Cont

Tightly focus light to generate x-rays

Course Plan• Introduction to light

– Waves– E-M Theory

• Light/matter interactions

• Optical Devices– Telescopes– Prisms

• Interference effects– Holograms– Gratings– Fourier Series

• Polarization – LCDs

• Optical Cavities– Lasers

What is Optics?

• Wikipedia: Optics is a branch of physics that describes the behavior and properties of light and the interaction of light with matter.

– What is “light”?

– How does light “behave”?

– How does matter effect light’s properties?

The study of light properties

through the centuries

• “Burning Glasses” in ancient Greek times

• Plato mentions light “bending”

• Alhazen (1000AD) studies mirrors

History Continued:

Wave vs. Particle

• Galileo (1609) builds telescope

to search the heavens

• Hooke (1665) proposes wave

nature of light

• Newton (1704) disperses light,

particle nature dominant

• Young (1803) and Fresnel

(1817) prove wave nature

through interference

History: Light Speed

• Romer (1676) used

planetary motion to measure

speed of light ~2.4x108 m/s

• Fizeau (1849) used a shutter

to measure the speed of

light 3.15x108m/s

• Speed of light is DEFINED

2.99792458x108m/s

History Cont.:

Electromagnetic Theory• Faraday (1845) use magnetic fields to alter light properties

• Maxwell (1873) unifies Electromagnetic fields

A

0 0

A

A

A

BE dl dS

t

EB dl dS

t

B dS 0

E dS 0

µ ε

∂= −∫ ∫∫

∂

∂=∫ ∫∫

∂

=∫∫

=∫∫

�� ��i i�

�� ��i i�

��i

��i

Faraday’s Law

Ampere’s Law

Gauss’s Law (Magnetic)

Gauss’s Law (Electric)

History Cont.

• Planck (1900) Quantizes

light energy

• Einstein (1905)

reintroduces light particles

(photons)

• 1920’s quantum

mechanics, light is both a

wave and a particle.

Wave Motion

2 2

2 2 2

1∂ ∂=

∂ ∂

y y

x v t

In general, waves obey the following equation

Question: What are some solutions?

= ±y( x,t ) y( x vt )For traveling waves

Electromagnetic Waves

Look in Appendix 1 for derivation

Maxwell’s equations lead to Electromagnetic wave equation

2 2

0 02 2

2 2

0 02 2

E E

x t

B B

x t

µ ε

µ ε

∂ ∂=

∂ ∂

∂ ∂=

∂ ∂

What is the speed of an Electromagnetic wave?

ε0=8.85x10-12 s2C2/m3kg µ0=4πx10-7 m kg/C2

Equating Electromagnetic wave

with light:

8

0 0

13x10 m / s

µ ε=

Maxwell: This velocity is so nearly that of light, that it seems we have strong

reason to conclude that light itself is an electromagnetic disturbance in the

form of waves propagated through the electromagnetic field according to

electromagnetic laws.

What is Light?

• Electromagnetic radiation

– The combination of propagating electric and

magnetic waves. But it is also a particle.

Electromagnetic Spectrum