Interference contrast

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Interference between two circular waves - wavelength increasing from top to bottom, distance between centers increasing to the right.

The interference contrast describes the visibility ( contrast ) of an interference phenomenon quantitatively. It is defined as the ratio of the intensities of two consecutive maxima and minima:

  • The optimal value is 1; in the case of the interference phenomenon being completely unrecognizable, it is 0.
  • This definition assumes that the mean intensity is the same . Then the amplitude is the same as the intensity . Thus applies: .

  • In the case of interference from light, the source-dependent coherence length is usually the limiting factor.

The interference contrast is especially important for interferometry , holography and phase contrast microscopy .