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thumb|The diffraction pattern Airy disk|(Airy disc) of a red [[laser beam projected onto a plate after passing through a small circular aperture in another plate]] Diffraction is the deviation of waves from straight-line propagation due to an obstacle or through an aperture, without any change in their energy. Diffraction is the same physical effect as interference, but interference is typically used for the superposition of a few waves, while the term diffraction is used when many waves are superposed. The term diffraction pattern is used to refer to an image or map of the different direction