Polarization of Light

Overview

• Light waves are electromagnetic waves composed of electric and magnetic fields.
• Electric and magnetic fields are perpendicular to each other.
• Focus primarily on the electric field for polarization.

Definition of Polarization

• Polarization refers to the orientation of the oscillation of the electric field in light waves.
• Polarized light: Electric field oscillates in one plane/direction.
  • Examples of polarization directions: vertical, horizontal, diagonal.
• Unpolarized light: Electric field oscillates in multiple directions.
  • Examples: Sunlight, incandescent light bulbs.

Polarization Methods

• Polarizers:
  • Materials that allow only light of a certain polarization to pass through.
  • Can be oriented to let through vertical, horizontal, or any specific angled light.

Applications of Polarization

• Polarized Sunglasses:
  • Reduce glare by blocking horizontally polarized light (common in reflected light from surfaces like water or roads).
• 3D Movies:
  • Use polarization to send different images to each eye, creating a 3D effect.
  • Circular polarization is often used because it's more robust to head tilts.

Types of Polarization

• Linear Polarization:

  • Light wave oscillates in a single direction.
  • Examples: vertically, horizontally, or diagonally polarized light.

• Circular Polarization:

  • The angle of polarization rotates in a circular motion.
  • Achieved by combining two light waves with a 90-degree phase shift.
  • Used in movie theaters for a consistent 3D experience regardless of head tilt.
  • Involves both clockwise and counterclockwise polarization directions.

Practical Implications

• Polarized sunglasses are beneficial for reducing glare and improving vision in reflective environments.
• Circular polarization in 3D glasses improves image stability and viewing comfort.