Lecture 1: Optical phenomena

Question 1

What are the different theories that are used to describe optical phenomena ?

Answer 1

• Classical electromagnetic theory
• Simplified models (e.g. geometric optics)
• Physical optics including diffraction and interference
• Quantum optics explains at submicroscopic level (where photons are important)

Question 2

What is classical electromagnetism

Answer 2

Study of electric charges and their motion.
Electromagnetic radiation is a self-propagating composite of an electric field.

Question 3

What are the four main forces in nature ?

Answer 3

1. Gravitation force (long range, acts on mass and energy)
2. Weak nuclear force (subatomic range)
3. EM force (Lorentz force, long range, acts on electric charge)
4. Strong force (subatomic range)

Question 4

What’s the Lorentz force ?

Answer 4

-The force exerted on a charged particle moving in an electric and
magnetic field.
- F = qE + qv x B
- Responsible for many phenomena, including binding of electrons to nuclei, intermolecular interactions.

Question 5

What do Maxwell’s equations describe regarding electric and magnetic fields ?

Answer 5

They describe how these fields are generated by charges, currents, and changes of the fields. In other words, they describe how light is generated and how it propagates.

Question 6

What are Maxwell’s equations/laws ?

Answer 6

• Gauss’s law (electric charges): electric fields are
  generated by single charges and diverge
• Gauss’s law (magnetism): no “magnetic charge”;
  magnetic fields are generated by dipoles and not
  originate in a single point
• Faraday’s law of induction: a spatially varying
  electric field is accompanied by a temporary
  varying magnetic field
• Ampere’s law: magnetic fields can be generated
  in two ways: by electric currents, and/or by
  changing electric fields

Question 7

What is the concept of permeability?

Answer 7

ability to support magnetic fields

Question 8

What is the concept of permittivity?

Answer 8

the capacitance that is
encountered when forming a electric field in a
medium.

Question 9

What are the different properties of light?

Answer 9

• carries electric and magnetic field - interaction with electric
  charges
• frequency - wavelength - energy
• momentum
• polarization
• coherence
• interact with gravity
• photon-photon interactions
• obey Bose-Einstein statistics (photons are bosons, more then one
  photon can occupy a given state)

Question 10

How does lasers differ from other light sources ?

Answer 10

• They operate using a single wavelength, and, as such, are monochromatic.
• They are coherent.
• They are directional. This means the light is spatially targeted, the light barely
  diverges. This contrasts with flashlights, for example.
• They are polarized.

Question 11

What are multiple applications of lasers in the biomedical and medical fields ?

Answer 11

• Optical tweezers
• Medical purposes (eg.: LASIK)
• Motion detection
• Mass spectroscopy
• Scanning
• DNA sequencing