English edit

 
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Etymology edit

Named after Dominique-François-Jean Arago, who performed an experiment demonstrating the spot's existence.

Noun edit

Arago spot (plural Arago spots)

  1. (optics) A bright point that appears at the centre of a circular object's shadow due to Fresnel diffraction.
    Synonyms: Fresnel spot, Poisson spot
    The Arago spot played an important role in the discovery of the wave nature of light and is a common way to demonstrate that light behaves as a wave.