Modeling and propagation of near-field diffraction patterns: A more complete approach

The aim of this paper is to discuss various diffraction theory models, probe the regions of validity of each, and apply appropriate models to some specific examples. The discussion could be incorporated into an advanced under- graduate or beginning graduate level course in optics. We first derive and compare various models for near-field light propagation. Then we calculate some representative two- dimensional intensity patterns and beam profiles for the near- field diffraction of infrared laser light. In the first example we apply near-field diffraction theory to the traditional ex- ample of the refraction of light at an interface between two media. The locations and intensity profiles are discussed as functions of the incident angle of the light and the refractive index of the medium. Finally, we investigate the propagation of light beyond the aperture and through a lens, yielding some interesting results that are verified experimentally.