Fundamental of Optical Engineering Lecture 6 extra

 This can occur when 2 or more waves overlap each other in space.  Assume that 2 waves have the same frequency.  The interference results in an addition of wave amplitudes.

 Two wave interference: the resulting field becomes

 Power density, P A

 If lights behave without interference, we would expect where E 1 and E 2 are orthogonal.  If there is an interference, it is clearly seen that the term is the term for “interference”.

 P A is max for  1 -  2 = 0,  2 , …,  2N   P A is min for  1 -  2 = ,  3 , …,  (2N+1)   Therefore,

Two wavesN waves Plane wave interferenceDiffraction grating Young’s double slit experimentInterference filters Reflection from film Electro-optic modulators Interferometers