Editing Coherence (physics) (section)

=== Examples of temporal coherence ===
Examples of temporal coherence include:
*A wave containing only a single frequency (monochromatic) is perfectly correlated with itself at all time delays, in accordance with the above relation. (See Figure 1)
*Conversely, a wave whose phase drifts quickly will have a short coherence time. (See Figure 2)
*Similarly, pulses ([[wave packet]]s) of waves, which naturally have a broad range of frequencies, also have a short coherence time since the amplitude of the wave changes quickly. (See Figure 3)
*Finally, white light, which has a very broad range of frequencies, is a wave which varies quickly in both amplitude and phase. Since it consequently has a very short coherence time (just 10 periods or so), it is often called incoherent.

[[Holography]] requires light with a long coherence time. In contrast, [[optical coherence tomography]], in its classical version, uses light with a short coherence time.