This is a computer simulation of the diffraction pattern that would be produced by passing a beam of monochromatic light through an aperture, or mask, of 18 point-holes equally spaced on the circumference of a circle.

For simulations of the diffraction patterns produced by (the vertices) of various aperiodic tilings, including the Penrose tilings, and for the theory behind these miraculous images, see my book "Quasicrystals and Geometry".