In physics, coherent backscattering is observed when coherent radiation (such as a laser beam) propagates through a medium which has a large number of scattering centers (such as milk or a thick cloud) of size comparable to the wavelength of the radiation.

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The waves are scattered many times while traveling through the medium. Even for incoherent radiation, the scattering typically reaches a local maximum in the direction of backscattering. For coherent radiation, however, the peak is two times higher.

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