Numeric simulations build a bridge from a two-slit experiment to the basics of X-ray diffraction and coherent optics

Numeric simulations based on the Huygens-Fresnel method allow one to develop intuition about the behavior of coherent light in diffraction and interference experiments. They give an opportunity to numerically observe and appreciate a number important phenomena, while avoiding the need to deal with the intricacies of their analytic descriptions. In an introductory teaching lab, they help to build a matrix of ideas, into which many optical demonstration experiments fall nicely and to the benefit of a student.