Introduction to diffraction. Part II: the far field

Abstract

The Fraunhofer diffraction is developed as a far-field approximation to the Fresnel-Kirchhoff equation. It is shown that the Fraunhofer formula can be recast as a one- or two-dimensional Fourier transform. Further, it is demonstrated that a lens, appropriately positioned with respect to the aperture, produces a Fourier or Hankel transform at the focal point.