Encyclopedia > Coherence time

  Article Content

Coherence time

Coherence time: For an electromagnetic wave, the time over which a propagating wave may be considered coherent.

Note 1: In long-distance transmission systems, the coherence time may be reduced by propagation factors such as dispersion, scattering, and diffraction.

Note 2: In optical communications, coherence time, τ, is calculated by dividing the coherence length by the phase velocity of light in a medium; approximately given by τ = λ2/(cΔλ) where λ is the central wavelength of the source, Δλ is the spectral width of the source, and c is the velocity of light in vacuum.

Note 3: "Coherence time" is usually applied to the optical regime.

Source: from Federal Standard 1037C and from MIL-STD-188

All Wikipedia text is available under the terms of the GNU Free Documentation License

  Search Encyclopedia

Search over one million articles, find something about almost anything!
  Featured Article
Dutch colonization of the Americas

... after, the first colonists, mostly from present-day Belgium and Germany, arrived in the new province. In 1626, director general of the WIC Peter Minuit "purchased" the ...