Spatial Coherence
In some systems, such as water waves or optics, wave-like states can extend over one or two dimensions. Spatial coherence describes the ability for two points in space, x1 and x2, in the extent of a wave to interfere, when averaged over time. More precisely, the spatial coherence is the cross-correlation between two points in a wave for all times. If a wave has only 1 value of amplitude over an infinite length, it is perfectly spatially coherent. The range of separation between the two points over which there is significant interference is called the coherence area, Ac. This is the relevant type of coherence for the Young’s double-slit interferometer. It is also used in optical imaging systems and particularly in various types of astronomy telescopes. Sometimes people also use “spatial coherence” to refer to the visibility when a wave-like state is combined with a spatially shifted copy of itself.
Read more about this topic: Coherence (physics)
Famous quotes containing the word coherence:
“Twentieth-century art may start with nothing, but it flourishes by virtue of its belief in itself, in the possibility of control over what seems essentially uncontrollable, in the coherence of the inchoate, and in its ability to create its own values.”
—A. Alvarez (b. 1929)