Beams crossing at an angle result in [[Interference Fringe]]s at their intersection $$ E_{1} + E_{2} = E_{0} \exp{i(kz\cos \theta + kx \sin \theta - \omega t)} + \exp i(kz\cos \theta - kx \sin \theta - \omega t) $$ $$ \implies E(x, z, t) = E_{0} \exp \left( i(kz \cos \theta - \omega t) \right) (2 \cos kx \sin \theta) $$ $$ \implies I(x, t) \propto 4I_{0} \cos^2(kx \sin \theta) = 2I_{0}(1 + \cos(2kx\sin \theta)) $$
- [[Fringe Spacing]],
$\Lambda$
[[Michelson Interferometer]]/[[Michelson-Morley Experiment]]