• Diffraction of electromagnetic radiation, including visible light,  refers to various phenomena that occur when an electromagnetic wave encounters an obstacle or passes through an opening.
  • Diffraction and interference are phenomena associated with all kinds of waves. Electromagnetic waves are a special case however because of their unique behaviour.
  • Diffraction of electromagnetic waves deals with the way light bends around the edges of obstacles into regions that would otherwise be in shadow.
  • Interference deals with the way that electromagnetic waves behave during the diffraction process.
  • Diffraction can be produced by the edges or by a hole (aperture) in any opaque surface or object.
  • Diffraction causes a propagating electromagnetic wave to produce a distinctive pattern as waves interfere with one another. The resulting pattern becomes visible if diffracted light subsequently strikes a surface.