Diffraction#

Scalar wave optics from Huygens through Airy: Huygens’ wavelet construction as diffractive spreading of a pinhole, Young’s double-slit interference fringes (including an animated sweep of the near-to-far-field wavefront propagation), Fresnel’s near-field diffraction theory and the Poisson/Arago spot, and Airy’s circular-aperture pattern and the diffraction limit it implies.