Gravitational lensing theory

The following sections are included:

• The lens equation

  • Point-like lenses

  • Extended lenses

• The surface brightness conservation

• Amplification

• Caustics and critical lines

• Fermat's principle

• Galaxy lens models

  • Circularly symmetric lenses

  • Non-circularly symmetric lenses

• The folded sky

• Folds and cusps

  • Magnification near a fold

  • Magnification near a cusp

  • The binary lens

• Recommended reading