If a wave is laterally periodic, then it is also longitudinally periodic. Nevertheless, lateral periodicity is not needed for longitudinal periodicity. Lateral quasi-periodicity is a more general case and sufficient for longitudinal periodicity. These results can be drawn from the Helmholtz equation, if the light is quasi-monochromatic and spatially coherent. For partially coherent light, similar results can be deduced from the Wolf equations. The triple correlation of a complex amplitude obeys a pair of wave equations, which are constructed exactly like the Wolf equations. Hence, the same laws on periodicity are valid. We present a historical and systematic view of all of those periodicity laws.
|Number of pages||4|
|Journal||Pure and Applied Optics (Print edition) (United Kingdom)|
|State||Published - Sep 1998|