1911 Encyclopædia Britannica/Diffraction of Light

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DIFFRACTION OF LIGHT.—1. When light proceeding from a small source falls upon an opaque object, a shadow is cast upon a screen situated behind the obstacle, and this shadow is found to be bordered by alternations of brightness and darkness, known as “diffraction bands.” The phenomena thus presented were described by Grimaldi and by Newton. Subsequently T. Young showed that in their formation interference plays an important part, but the complete explanation was reserved for A. J. Fresnel. Later investigations by Fraunhofer, Airy and others have greatly widened the field, and under the head of “diffraction” are now usually treated all the effects dependent upon the limitation of a beam of light, as well as those which arise from irregularities of any kind at surfaces through which it is transmitted, or at which it is reflected.



1. Article Introduction.
2. Shadows.
3. Fraunhofer’s Diffraction Phenomena.
4. Theory of Circular Aperture.
5. Resolving Power of Telescopes.
6. Coronas or Glories.
7. Influence of Aberration. Optical Power of Instruments.
8. Diffraction Gratings.
9. Talbot’s Bands.
10. Diffraction when the Source of Light is not seen in Focus.
11. Dynamical Theory of Diffraction.